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Aftermarket EFI - cont\'d

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tassupervee That really hurts doesnt it!

1,171 posts · joined Sep 2003 ·

#220584
1302Steve wrote:The money Ive spent on EFI on my car I could have bought a EJ20T.
1302Steve
You make a very valid point Steve. Ratty has unloaded a heap of money into the delco setup that IMHO, would have been far better spent on somethying like a Microtech MT-8 of an EMS Stinger.
Both these systems come ready loaded with a working map for your car and with more features available that a V-dub could ever dream about utillising, on the fly tuning for barely a grand with a loom,,, but,,,,, nonetheless, the guys like ratty that have persisted with the like of their installations will have the satisfaction of making it all work themselves.

Just cant put a price on that I reckon.

More power to them!

L8tr M8
E

[Edited on 18/8/04 by tassupervee]
Im not a complete idiot, quite a few parts are missing....

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 ·

#220605
Hi

If we wanted an easy life we would not have picked VWs to fool around with. I was offered a twin turbo suby motor the other day with harness and computer, $1200.

I was at friend workshop the other day, he had the Delco guru with him and they were tuning a really mean 5.7 dunnydore with the Delco stuff, have to say I was pretty impressed with what he showed me. But I think he was showing me all this stuff because my mate told him I was running Autronic.

1302Steve

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 ·

#220606
Pushed the button twice:bounce

[Edited on 19-8-2004 by 1302Steve]

tassupervee That really hurts doesnt it!

1,171 posts · joined Sep 2003 ·

#220625
Steve
If the Autronic was running with a closed loop mode then i would have had that system anytime. as a standalone management system anyway.
I have an old EMS T1 on my wifes Pulsar Turbo and it is fantastic old system.
I have identified a few shortcomings with the tuning parameters but these shortcomings are so insignificant when compared to ANY carb setup as to not be there at the end of the day.!

Nah, I have a lot of respect for you guys that do it all the hard way!!

L8tr
E
Im not a complete idiot, quite a few parts are missing....

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 ·

#223443
Hi all,

I think I have just about had it all happen.... this one has me stumped:

I have noticed that a couple of minuites of running the high pressure pump begins to make a ticking noise. I know that these pumps are not supposed to make noises other than a hiss whilst they are running so I know that this is not good. Initially I thought that the pump may have been damaged (it was from an unknown source) so I purchased another one and it does it too.... If you leave it running for any more than about 3 mins the engine begins to lean out.

I have now noticed that when you remove the fuel supply hose (surge tank to pump) from the fuel pump after the car has been running there is a 'sucking' noise as you 'crack the seal'. As the pump is right under the surge tank I also noticed that you can hear an air bubble (I assume) in the surge tank. Initially, when you remove the hose from the pump, almost no fuel comes out of the hose. Then, after the air bubble in the surge tank, the fuel poors out....so it would appear that a vaccum is being generated in the surge tank!?!

I have been back over the info that I found when constructing this system and I have noticed that in almost every case, the return line from the fuel reg is routed into the main fuel tank. I haven't done this, instead I have routed it back into the surge tank, and I think this is where the problems is...but I don't know why! Can anyone even attempt to explain this to me?

Just a few more details about my system and the way it is connected: The surge tank is about 2 litres in capacity. It has 4 hose fittings in it - 2 in the top and 2 in the bottom. The 2 in the top are connected to the main fuel tank - one with a low pressure pump, pumping fuel from the main tank to the surge tank, the other returning unused fuel and any air back to the main tank. The two fittings on the bottom are the supply to the high pressure pump and the return from the fuel regulator....
Ratty has unloaded a heap of money into the delco setup that IMHO, would have been far better spent on somethying like a Microtech MT-8 of an EMS Stinger. Both these systems come ready loaded with a working map for your car and with more features available that a V-dub could ever dream about utillising, on the fly tuning for barely a grand with a loom.
Tassupervee, I have spent about the same money as this on the Delco ECU, however I did have to purchase and modify the loom (but a wiring loom from a Camira is cheap and easily available and also requires very few mods). OK, so the map I started with is a Camira map, but a VW will start and run on a Camira map (although a little rough). Have you seen a Delco/Kalmaker set-up in use? Not much you can't do. Remember that regardless of which ECU you choose, you still have to purchase fuel pumps, TB(s), an O2 sensor, fuel rails and hoses, MAP sensor, CHT sensor, injectors, surge tank, not to mention the dozens of hose clips, bolts, nuts, washers, etc that go into the mechanicals of the system. This is where around half of the set-up costs have gone with my system - hence the $2000 price tag.

I personally liked the Delco/Kalmaker system. I had heard good things about it from speaking to people who had used it I had also heard bad things about some of the other brands (some sensitive to voltage fluctuations, some poor after sales service, some a lack of information), so this influenced my decision. I am very happy with the Kalmaker software and its abilities - I have had no issues with the ECU and software at all - all my problems have been mechanical. Something that would effect any brand of ECU.

My suggestion to anyone looking to attempt a FI conversion is to shop around an talk to the users of these systems. This is where you will hear most of what you need to know about reliability (both in day-to-day running and stupidity proofing:thumb ). Look at what they can do and compare this to what you want it to do. There are dozens of options to choose from....

There are a couple of ready made systems available from sources overseas - both of the systems that I looked at appeared to be quite good, however I was concerned with the spare parts situation, are they interchangeable with parts available in Australia or do I have to purchase everything from the US. The price for these systems is also quite high (higher that what I have spent on my system I think, and you would still have to supply a surge tank, fuel lines and modify your main tank for a fuel return line.....) Have a look around the CB performance site or the Webber site. Sure, they would be easier, but $$$$$......

OK, enough from me, I'm going to see if I can understand what is going on in my surge tank:puke Any ideas?

R🙁
40hp, 6V and ...er... slowly making improvements 😂

It's nice to be important, but it's more important to be nice!

Founding member of the Gold Coast Dub Club Inc. 🙂

Baja Wes V6 Baja Pioneer

3,119 posts · joined Aug 2002 ·

#223489
sound kinda similar to the weird cutting out problem I had with my surge tank set-up, but your set-up is now similar to my corrected set-up so I wouldn't have thought you'd have any problems.

It sounds like the surge tank is starving for fuel.

Have you connected the low pressure pump backwards so it is pumping from the surge tank to the main tank? That would start the HP pump of fuel.

Is the fuel line from the surge tank to the HP pump big enough, free of restrictions, tight bends, filters, etc?

Put your hand on the surge tank, is it getting warm at all?
Wes - www.offroadvw.net - 200HP Quad Cam V6 in a VW Baja - with climate control... 🙂
www.taylorcycles.com.au - My DH MTB racing brothers shop.

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 ·

#223530
Hi Wes,

...yeah, it sounds like that, however I have dissconnected the low pressure return line from the surge tank to the main tank and have extended the hose so that I could run it back in through the filler hole of the main tank - this way I could see what the return to the tank looked like and check for air, surging fuel pressure, etc. The return is constant and contains no obvious air bubbles. I then removed both the low pressure lines from the surge tank and started the car (with the low pressure pump disabled:duh). The idea here was to use the two hose fittings at the top of the tank as vents (to ensure no vac in the tank). It still stalled (the surge tank was still at least half full). The vac seems to be forming in the hose between the pump and the surge tank....?!?

The hose between the pump and the surge tank is quite long which is not really necessary (I just had a spare piece of fuel hose, so this is what I used - I had planned on trimming it to the right size once I have everything mounted.) It is currently all above the height of the pump, so no air should be trapped. The only two things that I can think of are a) I have used right angle fittings on the bottom of the surge tank so that the hoses are kept up as far as possible - perhaps the restriction of the right angle is causing some sort of problem (but I wouldn't think so!) or b) the return from the fuel regulator contains so much air that it is being drawn into the pump (I wouldn't think that this would be correct either, but I'm clutching at straws here...)

The hoses are all free of restrictions and the filter on the HP side of the system is after the pump.

The surge tank is stone cold, as are all the fuel lines and rails.... the engine is only running for around 2 mins before the pump begins to make noises so I wouldn't think that there would be enough time for anything to get hot...?

Hmmmmm

R 🙁
40hp, 6V and ...er... slowly making improvements 😂

It's nice to be important, but it's more important to be nice!

Founding member of the Gold Coast Dub Club Inc. 🙂

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 ·

#223532
Wes, I just had another look at your web site and the only difference between your surge tank set-up and mine is the fact that you are using an internal pump and mine is external - again, I wouldn't have thought that would cause any sort of problems....

R 🙁
40hp, 6V and ...er... slowly making improvements 😂

It's nice to be important, but it's more important to be nice!

Founding member of the Gold Coast Dub Club Inc. 🙂

Baja Wes V6 Baja Pioneer

3,119 posts · joined Aug 2002 ·

#223601
what size line are you running to the HP pump?

That line should be very short, as short as possible. It should preferrably be straight with no bends.

Right angle bends are bad for flow. One right angle bend is equivalent to a few meters of straight pipe pressure loss wise. Then you sound like you have a big length of pipe on top of that. That's bad for fuel flow. The high pressure pump is trying to pump that fuel at a pretty fast rate, so it loses alot of pressure in the lines leading up to the pump. I don't have the problem as my pump is swimming in the fuel.

Fuel has a very high vapour pressure, meaning it doesn't take much of a pressure drop (or temperature rise) for it to vaporise. I think that's what's it's doing. It vaporising in the pump, known as cavitation. It makes weird little crackle rattle kinda noises when it's bad enough.

Try as little hose as you can before the pump, it should be a decent diameter too.
Wes - www.offroadvw.net - 200HP Quad Cam V6 in a VW Baja - with climate control... 🙂
www.taylorcycles.com.au - My DH MTB racing brothers shop.

Baja Wes V6 Baja Pioneer

3,119 posts · joined Aug 2002 ·

#223629
here's a good link that some may find handy, it talks about converting from carby to EFI

http://www.autospeed.com.au/cms/A_0520/article.html

I have the 21st Century Performance book written by that guy, and he knows his stuff.

He basically saiys you need at least a 1/2" line to feed the EFI pump, and it should be mounted as close as possible (and always below the fuel level). Most of the guys running surge tanks for conversions or track use have a 1/2" outlet on the surge tank, point striaght into the HP pump. No bends or anything, and a very short length of hose.

Another company that sells intank pump kits has the following to say about fitting external pumps...
Common problems associated with stock fuel tanks and fabricated pickups are pump cavitation, vapor lock, varying fuel pressure, exaggerated pump wear and lean conditions during both low and high loads. Note: Unlike a carbureted engine, any loss of fuel supply at the in-tank- pickup will immediately result in a loss of fuel volume and pressure at the EFI injector resulting in lean conditions and engine damage.
hinted at potential problems with starving the HP pump of fuel.
Wes - www.offroadvw.net - 200HP Quad Cam V6 in a VW Baja - with climate control... 🙂
www.taylorcycles.com.au - My DH MTB racing brothers shop.

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 ·

#224040
Thanks Wes,

All of that info says what I was thinking. I suspect that the length of hose is causing the problem - that, coupled with the right angle hose fitting in the tank is likely to be the cause. I will go and shorten the length of hose between the fuel pump and surge tank and give it another go.

I spoke to my Brother about this problem too, and although he wasn't sure of the cause he suggested that I check inside the surge tank for foreign objects that could be partly blocking the hose fitting. Apparently he has seen something similar in a Kombi that he had at work once - it had lolly wrappers in the fuel tank :duh that would float around in the fuel until one was drawn over the tank outlet by the fuel flow. It would then block the outlet and the engine would stop. Once the engine stopped, so would the fuel flow and the wrapper would float away from the tank outlet, so the car would then re-start OK - strange but true! My Surge tank in new and I don't store my lolly wrappers in the fuel tank 😀 so I can't imagine that being the cause, but I will have a look whilst I have it all apart anyway.

I think that if I was to re-make the surge tank again, I would create it so that it suited an internal pump for a couple of reasons:

1. One less thing to have to mount = less hose
2. Internal pumps are usually cheaper than external pumps
3. There is no length of hose/right angle fitting issues!

Finally, that drawing above is Identical to the set-up that I have, except I have my return from the fuel reg going into the bottom of the tank. I am using a fitting in the bottom of the surge tank that is the same diameter as the hose fitting on the pump - obviously the hose between the two is the correct size to suit.

I'm off now to shorten the hose and check the internals of my surge tank - I'll post the results.....

R :duh
40hp, 6V and ...er... slowly making improvements 😂

It's nice to be important, but it's more important to be nice!

Founding member of the Gold Coast Dub Club Inc. 🙂

tassupervee That really hurts doesnt it!

1,171 posts · joined Sep 2003 ·

#224263
Ratty
Once again I am not casting aspersions at your choice of clobber.
I believe that the delco/kalmaker combo is very tuneable.

However, I have had the benifit of using both EMS T1-4 on my wifes turbo e15et (pulsar) and the Microtech MT-8 on my FJ20et.
Plus I have had experience with other Microtechs on atmo and turbo rotors.

I have dealt with both Dom (Microtech) and Pete (EMS) and only have good experiences with them.

Both the systems came ready to run and both systems did exactly that and I enjoy the fact that when I identify a tuning issue with either of my systems I simply reach under the seat, grab the handpeice and tune away based on the EGO readings.

Its all too easy.

I get a bit suspicious of up to 20 year old electronics and wiring hardware ratted from wrecked cars thats all.
Id much rather start from fresh with a spankers loom custom fitted to my particular application.

Anyway keep at it dude and best of luck.

L8tr
E
Im not a complete idiot, quite a few parts are missing....

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 ·

#224528
Tassupervee,

I s'pose it all comes down to what your are most comfortable with - and I can deffinatly see why you would want to start with a brand new wiring loom! This just proves that any recommendation (of a brand/model) comes with some personal preference included and is not just based on facts and figures. There are many good systems out there - it's just a matter of finding the right one for you....

On the subject of what appears to be my fuel starvation problem, I have spoken to many people today and it would appear that I am creating a vacuum in my surge tank by using hose fittings and hoses that are too small on the low pressure side. I don't completely understand why (I think you would need a degree in hydraulics to understand!:thumb), but this is the basics of it, as explained to me by someone who has studied hydralics:

'When using a two pumps in a system including a system that contains a storage container (surge tank in my case), the highest flow rate of the of the two pumps is what controls the flow rate of the system.'

Let me see if I can give you an example - I looked around and found these figures in another post regarding surge tanks:
a few figures for the interested, fuel flow from EFI pumps, all at 40psi.

XE falcon = 1.8 L/min
VL holden = 2.3 L/min
6.9 Merc = 2.7 L/min
R32 GTR skyline = 4.5L/min
facet fuel pump is rated at 2.2 L/min flow
Now, my HP pump is a VL Commodore unit (rated at 2.3L/min) and my low pressure pump is a facet pump (rated at 2.2 l/min) - therefore it is possible that the HP pump is trying to draw 2.3L/min and the LP pump is supplying 2.2 L/min

If this was the situation this would mean that:

2.2 - 2.3 = -0.1 <- this negative value indicates that in a system like this, a vacuum is being created. If the value was positive it would indicate that there was pressure being created in the tank, which may cause other problems (although not likely in my case as there is a return line to the main tank which, I think, would allow this pressure to escape)

Now I know that my LP pump would be having trouble flowing 2.2 L/min as the hoses and fittings are way too small, so I will upgrade them tomorrow (er, actually later today:P) and do my own tests.

I will also take the time to test the pump that was originally sold to me as a high pressure pump, but turned out to be a low pressure pump - I think that it will flow better than the facet pump - time will tell.

Of course, if I have this all ass-up and anyone would like to correct what I have written, please feel free as I don't wish to mislead anyone! I also realise that this is a very 'dumbed down' version of what is really happening so that I could be made to understand the basics and there is a lot more to it! :thumb

Just before I sign off, Wes, what size hose are you using between your fuel tank and the surge tank? This may explain why our systems are basically identical but yours works and mine doesn't.

OK, thats it for now - time for bed!

R🙁
40hp, 6V and ...er... slowly making improvements 😂

It's nice to be important, but it's more important to be nice!

Founding member of the Gold Coast Dub Club Inc. 🙂

Baja Wes V6 Baja Pioneer

3,119 posts · joined Aug 2002 ·

#224557
Ratty,

Whoever explained that to you has led you up the garden path, and completely confused you.

What they are describing, is what would happen if your HP pump / fuel rail return line was returning to the main tank. Then your LP pump would have to keep up with your HP pump. This is why I have told people not to return the HP pump to the main tank.

But with your set-up, the HP pump goes from the surge tank, thru the fuel rail, and back to the surge tank. That is a relatively closed loop that fuel could circulate around forever.

But when the engine is running fuel is lost from that loop, through the injectors and into the engine. The LP pump only has to supply enough make-up fuel to the surge tank to refill what is lost through the injectors. This is much less fuel than what the HP pump is actually pumping.

So you LP pump is not causing you any issues. When I first set-up mine I didn't even have a LP pump and let it gravity feed into the surge tank. The problem I had then was then closed loop of HP pump > fuel rail > surge tank kept recirculating and eventually made the fuel to hot and caused a kind of vapor lock. So my LP pump is simply installed to circulate fuel from the surge tank to the main tank to even out the temperature.

Basically the LP pump will be pumping heaps of fuel to the surge tank, the engine will hardly use any of it, and the majority will simply return back to the main tank.

My LP pump lines are 10mm, but that's because they started off as gravity feed lines.

My HP pump lines are 8mm. If I had an external HP pump I would use a 1/2" line to feed it.

Trust me, your LP set-up isn't causing your problems.
Wes - www.offroadvw.net - 200HP Quad Cam V6 in a VW Baja - with climate control... 🙂
www.taylorcycles.com.au - My DH MTB racing brothers shop.

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 ·

#224565
Hi

Leigh and I are both using Carter lift pumps, not sure of their rating and we both return our fuel to the tank, never had a problem.

Steve

Baja Wes V6 Baja Pioneer

3,119 posts · joined Aug 2002 ·

#224575
I imagine the carter lift pumps have a healthy enough flow rate to keep up with the HP pump. If it wasn't quite enough it would suck itself through the return line from the surge to the main tank anyway (I assume you have this line otherwise you'd be pressurising your surge tank).

I guess the main point is that the LP pump is not causing the issues that he's experiencing.
Wes - www.offroadvw.net - 200HP Quad Cam V6 in a VW Baja - with climate control... 🙂
www.taylorcycles.com.au - My DH MTB racing brothers shop.

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 ·

#224609
Hmmm, thanks guys....

Looks like time to experiment and see if we can improve things.... I am going to change surge tanks to my brothers tank as his is larger in capacity... I am also going to experiment with where the hoses connect to the surge tank to see if I am not creating some sort of fuel swirl inside the tank which is causing it do to strange things....

This has got me stuffed....

R 🙁
40hp, 6V and ...er... slowly making improvements 😂

It's nice to be important, but it's more important to be nice!

Founding member of the Gold Coast Dub Club Inc. 🙂

Baja Wes V6 Baja Pioneer

3,119 posts · joined Aug 2002 ·

#224629
What size line is feeding your HP pump now?

Have you moved it close to the surge tank?

Can you get rid of the 90 degree elbow?
Wes - www.offroadvw.net - 200HP Quad Cam V6 in a VW Baja - with climate control... 🙂
www.taylorcycles.com.au - My DH MTB racing brothers shop.

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 ·

#225118
OK, I have tried a number of configurations - all with no luck...

Wes, I have about 3 inches of 12.7mm fuel hose between the bottom of the surge tank and the inlet of the HP pump. As yet I haven't removed the right angle fitting (its the Gold Coast Show holiday today, so nothing is open 🙁 ) I'll change it first thing tomorrow morning after I visit the hose suppliers.

I have upgraded the fuel line from the main tank to the surge tank (and all the fittings) to 8mm hose and I have tried fitting the low pressure pump both under the surge tank and under the main tank. I am now feeding the low pressure fuel into the surge tank through the bottom of the tank and returning the fuel from the fuel rail/regulator through the top of the tank. The inlet to the HP pump is now directly opposite the return from the reg....

I have even checked the voltage at the fuel pumps again today to be certain - both have 12.9 - 13.1 at an idle, so I can't see it being a voltage issue....

I pulled the return line off the surge tank with the engine running and there is a good amount of fuel being returned back to the tank - (I hate it when you squirt yourself in the face with petrol - Yuk :puke ).... this makes me think I might be looking in the wrong place.....

Can anyone tell me, if there is too much fuel being returned to the surge tank (via the fuel reg) what would the HP pump be likely to do? I know that this would cause the engine to run lean - particularly if the pump could not get enough pressure to the injectors.....

Also, last night, whilst making one of a hundred Pizzas at work, I realised that I didn't know what a Carter pump is/does/looks like - can anyone give me a description (or even a photo)?

Unless someone here can come up with another idea, I think I will do a couple of things tomorrow and see what effect they have:

1) replace the right angle fitting in the bottom of the surge tank.
2) remove the surge tank completely and fit the HP pump directly in the line from the fuel tank - not permanantly, but as an experiment to see if it still has its rattling fits after a couple of minuites.
3) if 1 doesn't fix the problem and 2 does, then I will fit up my brothers larger surge tank and try that - can't see how it will make a difference, but you have to try it to know....

...any other suggestions? I'm getting desperate! :bounce

Whilst I'm asking questions - is just wonder if it is necessary to 'force feed' the VL pumps.... does any one know?

OK, I've had enough for today - I'm going to work.

R 🙁
40hp, 6V and ...er... slowly making improvements 😂

It's nice to be important, but it's more important to be nice!

Founding member of the Gold Coast Dub Club Inc. 🙂

AdrianH Officially Full-On Dubber

257 posts · joined Mar 2004 ·

#225128
This may sound stupid, but have you tried to run it with the fuel tank cap off ? Just in case there is a vacuum problem there ??. Main tank vent blocked or non existant ?

FWIW - you lose about 5% flow with a 90 degree bend

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 ·

#225130
I have tried to run it with the fuel tank cap off - no difference (unfortunatly).

Silly question time - if I remove the vacuum hose off the top of the fuel regulator, that should increase the fuel pressure causing the engine to run rich shouldn't it? Mine doesn't - have I got an issue with the fuel reg??? Put that on the list of things to check tomorrow - I know that the quantity of fuel returned from the reg at an idle should be around 750ml/30secs (or so I am told)....

I'm so confused:duh

R 🙁
40hp, 6V and ...er... slowly making improvements 😂

It's nice to be important, but it's more important to be nice!

Founding member of the Gold Coast Dub Club Inc. 🙂

Baja Wes V6 Baja Pioneer

3,119 posts · joined Aug 2002 ·

#225478
AdrianH wrote:FWIW - you lose about 5% flow with a 90 degree bend
I don't know where that came from, but it's not correct.

If you only have a 90 degree bend, then it is basically 100% of your friction loss. What effect those losses have on the actual flow rate depends on the pressure-head curve of the pump. Therefore you can not apply any rules of thumb like you suggested. And all that really applies to the HP-discharge side of the pump.

On the suction side is a different matter. The pump will have a NPSHr - net positive suction head required. The NSPHa (available) must be higher than the required for the pump. By having restrictions (such as 90 bends or filters) before the pump, you are lowering the NPSHa. If it drops below the NPSHr then you get cavitation > pump damage > reduction or loss in pump flow. All this can acutally be calculated if you have the data for the pump (NPSHr), but I don't like your chances of finding it for a car fuel pump. I've done the calculation on way too many industrial pumps to count though.

Anyway, back to the story. the vacuum line to the regulator will vary the fuel pressure, but only a relatively small amount compared to the high pressure the fuel is delivered at. I'm not sure your air fuel read-outs would be sensitive enough to see the effect of removing the vacuum hose off the regulator.

Sounds like you need a fuel pressure guage. See what happens to the actual fuel pressure. Really no matter what the regulator is setting the pressure at (within reason) you'll get a similar amount of fuel getting returned back to the surge tank. So calculating that flow probably won't tell you alot. You won't be able to say "oh I'm getting too much fuel returned to the surge, it must be running lean and not getting enough fuel pressure", it doesn't work like that.

Another thing that I thought about, do you know what duty cycle your injectors are working at?

The reason I ask is that by running batch mode your injectors work more often (but not for as long) than in sequential injection. If your running a high duty cycle then maybe the injectors are overheating after a few minutes of running and causing your troubles. It would also have probs when revving the engine using full throttle too is that was the case. Just something else to consider...
Wes - www.offroadvw.net - 200HP Quad Cam V6 in a VW Baja - with climate control... 🙂
www.taylorcycles.com.au - My DH MTB racing brothers shop.

AdrianH Officially Full-On Dubber

257 posts · joined Mar 2004 ·

#225738
Hey I am reading a book called Forced induction performance tuning, in it it states " Some however choose to use a small pump to feed the swirl pot and run the fuel return line back to the swirl pot rather than to the fuel tank. I do not believe this is a good idea for two reasons: unless the swirl pot is fairly large it can run dry at high engine loads and high RPM, and second, at lower engine loadings the fuel will get hot circulating in a closed loop and the engine could become dangerously lean"

Might help ??

Baja Wes - thanks for the flow info...

tassupervee That really hurts doesnt it!

1,171 posts · joined Sep 2003 ·

#225750
Aidrian, I cant see your logic here dude.
If the engine fuel return is fed to the surge tank, the chances of the surge tank running out are actually significantly lessened.
The lift pump only has to deliver enough fuel to cover what the engine uses. In most cases, this will be easily covered by nearl any electric fuel pump.
If the engine fuel return is piped direct to the main fuel tank, the lift pump has to cover what the engine uses AND what the fuel pressure regulator bypasses.
This is often in excess of what many single electric fuel pumps can cover.

The fuel gets warm yes but since it is technically not a closed loop in practise the fuel does not get overly hot as the lift pump is always supplying some fuel into the pot to replace what is used, even at idle and the pot by its nature looses heat like a radiator.

The heating of the fuel in the surge tank is relatively insignificant in the overall scheme of things.
Im not a complete idiot, quite a few parts are missing....

tassupervee That really hurts doesnt it!

1,171 posts · joined Sep 2003 ·

#225753
Ratty
You have described your surge tank LP feed, HP feed and engine bypass returns.

Obviously, the HP feed needs to be at or near the bottom of the tank, the engine bypass return should be above this to prevent hot fuel and/or any air directly recirculating same with the LP supply from the lift pump.

Where exactly is your surge tank vent/return back to the main tank? At the very top I presume?

Just a thought.

L8tr
E
Im not a complete idiot, quite a few parts are missing....

AdrianH Officially Full-On Dubber

257 posts · joined Mar 2004 ·

#226134
Tas, its someone elses logic - direct quote 🙂

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 ·

#226206
Thanks for your input guys - I have a confession to make:

I have finally found the problem - but it's not over yet....

I discovered when I removed the return line from the top of the surge tank (the one from the fuel reg) that the flow was ... er ... significantly less than what I was told... actually there was nothing coming out at all at any time, regardless of engine revs. It would appear that the fuel reg is blocked or faulty in some way and no longer allows the returned fuel to go through - it's always the things you check last and/or assume are working OK that catch you out.

I assume that this would have been causing the pump to get to full pressure, overheat and boil the fuel, causing the strange vaccum that I observed.

Strangly now, having replaced the pressure reg with one from a running VL (have you ever tried to get one of these out of a VL - don't! Pay someone else to do it - not easy!) I am unable to get the engine to run correctly - it's always lean unless I run the injectors at almost 100% - and thats just at idle! Before I start looking for more equipment failures, I'm going to reset the Calabration in the ECU and check the fuel pressure at the injectors...

If its not one thing, its another!

I'll let you know how it all goes....

Thanks again guys - I appreciate the help. 🙂 :kiss

Just something I noticed - does anyone know what the fuel damper does in the GM fuel systems - no manuals make any mention of their function, just how to remove and install them - I don't have one (and as far as I know neither do the Kombis, which use a very similar system) - they are mounted just after the high pressure pump, usually under the rear of a Commodore/Camira.

Thanks again (geez I feel stupid for not checking that earlier :blush )

R

[Edited on 30-8-2004 by ratty 63]
40hp, 6V and ...er... slowly making improvements 😂

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Baja Wes V6 Baja Pioneer

3,119 posts · joined Aug 2002 ·

#226231
ratty 63 wrote:actually there was nothing coming out at all at any time, regardless of engine revs.
Well that would certainly explain your problems. Not very good for the pump, and probably quite dangerous too. I woulda thought the fuel filter might have started getting hot, also pays to check that things that are supposed to be cold actually are cold.

I've seen industrial pumps (we're talking 300mm diameter suction and discharge piping) that have been operating away happily, and then some idiot closes the discharge valve, stopping flow in a similar fashion to your fuel reg. Anyway it operates like that for a while, but the heat of churning the fluid inside the pumps builds and builds until the fluid in the pump boils, then probably starts superheating. The pressure in the pump builds so much the pump physically expodes, it's like a bomb going off. We found one large chunk of cast iron pump casing about 20m away from the pump.

Anyway, back to the thread. Don't know what a damper does, but going by the name I'd say it dampens. Either the pump design, or the injectors working, must cause pressure pulsations in the fuel lines, and I guess the damper is there to try to dampen the pulsations out.
Wes - www.offroadvw.net - 200HP Quad Cam V6 in a VW Baja - with climate control... 🙂
www.taylorcycles.com.au - My DH MTB racing brothers shop.

Midlife crisis Nartispuddlejumper, Bureau of Toxicity

2,282 posts · joined May 2003 ·

#226254
After read some posts on an US site about FI Wes you hit the button on the head it is there to stop the pulsations, so the injectors get a steady flow of fuel

Marc
If you can't laugh at yourself you can't laugh at anyone else! Because life is to short not to LAUGH