'78 EFI Bay hard to start - FIXED

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 · 11 Jan 2010, 9:19 pm

#757085

Hi Volks

Have been enjoying my '78 Auto EFI Bay for about 18 months now - purchased as a twin carbed engine it gave me nothing but trouble (always associated with the carbs😠) - so I picked up a complete engine and factory EFI system and converted it.

It runs fantastically - far more reliable and less fussy, but it has a small quirk on start-up. I'm sure I could find it if I spent a few hours hunting around the engine bay and comparing figures .... but I don't have a few hours all in a row - so it could take me months! This is where I hope someone here can offer some suggestions to make the fault finding process a bit faster.

When starting cold, it will crank for ages without so much as a splutter - holding the throttle open improves the situation, but it still takes 1-2 mins of cranking to start.

Interestingly, starting the engine (from cold) becomes easier and easier as the air temp rises. At around 28 deg (mid morning) it will start after about 10 seconds of cranking, sometimes even with the throttle closed.

Once the engine starts it will idle very slowly until it warms up and is prone to stalling if I stab the throttle (at idle) whilst in gear (remember - it is an auto).

All these problems do not exist once the engine has been run for more than a few minutes.

I know that there are a number of temp sensors (3 I believe) in the factory set-up, and from my experience I feel that it is going to be one of them that is faulty or has a bad connection or broken wire. Question is (assuming that it is a faulty temp sensor), which one? Or should I be looking elsewhere for the problem?

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. 🙂

Andy Andy\'s Adventures

2,820 posts · joined Nov 2002 · 11 Jan 2010, 11:24 pm

#757116

There's a wealth of info here http://www.ratwell.com/
Having not worked on EFI motor's, I can't be a lot of help, but I would guess temp sensors as you said and I think '78 has a 5th injector for cold starts that could be playing up?
Don't forget to also ensure the ignition is up to scratch, and does the '78 dissy have a second set of points for the EFI?

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 · 12 Jan 2010, 8:35 am

#757140

Andy wrote:There's a wealth of info here http://www.ratwell.com/
Having not worked on EFI motor's, I can't be a lot of help, but I would guess temp sensors as you said and I think '78 has a 5th injector for cold starts that could be playing up?
Don't forget to also ensure the ignition is up to scratch, and does the '78 dissy have a second set of points for the EFI?

Thanks Andy - I'll have a closer look at that website...

Yep, the stock EFI has a 5th injector (cold start injector) that is mounted in the plenum chamber. I am told by a reliable source that the cold start injector only operates when the air temp is close to (or below) zero degrees - can anyone confirm this? I'm fairly sure that my cold start injector is not working, but if it only triggers at around zero degrees I'm not really going to need it on the Gold Coast 😀

The fact that it seems to idle too slowly once it does start indicates to me that it is too lean (no cold enrichment - similar to a choke on a carb).....

Ignition has brand new points and condenser - the Kombi EFI only uses one set of points (not like the Type III system).

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. 🙂

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 12 Jan 2010, 8:50 am

#757143

I had a similar problem on an air cooled T3

Dunno if it is the same motor
Mine had hydraulic lifters

Had to crank and crank

Was getting a leaky push rod tube replaced and mechanic saw that a circlip in the lifter had come out
Never saw my self - but guessing this was haolding a valve open??

Whatever - that cured my cranking problems

Barry

Futue te ipsum!!!

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 · 12 Jan 2010, 11:05 am

#757161

Unfortunately mine has solid lifters ... the next one will be hydraulic (currently collecting parts)

Did this only effect starting when it was cold?

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. 🙂

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 12 Jan 2010, 11:44 am

#757169

ratty 63 wrote:Did this only effect starting when it was cold?

Pretty sure
It was 5 or so years ago now

Futue te ipsum!!!

toplessbug Fahrvergnugen

879 posts · joined Aug 2002 · 12 Jan 2010, 11:01 pm

#757309

HI Ross,first thing i would replace is the temp sender 2 in the head,it can and does cause all sorts of weird problems and make sure the connector is sound as well ,you cant really measure to check as i have had ones that measure ok but were absolutely faulty also check your aux air valve

Don't argue with an idiot; people watching may not be able to tell the difference.

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 · 12 Jan 2010, 11:56 pm

#757315

Strangely enough, I have a brand new Temp Sender 2 somewhere in my shed (used it for about a week on the Delco EFI system that I set-up on a 1600 many years ago) - I'll dig it out and swap it when I get a moment and see what effect (if any) this has.

If this has no effect I will move on to the aux air valve - as far as I understand, if this was faulty the engine idle would be unreliable at particular temps (like mine is when cold) depending on if it is stuck open, closed or part way between the two.... is that correct?

Thanks for the advice - I'll let you know how I get on.....

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. 🙂

matberry Moderator Go hard or go home

8,114 posts · joined Mar 2006 · 13 Jan 2010, 7:56 am

#757326

Sounds like you guys are on the right track.

Keep up the good work. 🙂

Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE

ratty 63 Custom Title Time!

1,083 posts · joined Oct 2003 · 19 Jan 2010, 11:41 am

#758307

Hi all,

Just a quick update....

Spend some time over the last couple of days checking as much of the EFI system as I can - using one of the many service manuals as a guide.

Neither of the temp sensors appear to be out of the 'expected range' - Haven't found my spare Temp Sensor II yet, but will keep looking (must be close now! 😀)

The Aux Air valve appears to be working correctly (how can you tell if it is opening enough when cold?)

Re-read the manual regarding the operation and testing of the cold start injector - the manual claims that it will trigger (ie: inject fuel) if the air/engine crankcase temp is below either 35 deg C or 50 Deg C (depending on which thermo-time switch you have fitted). My Cold Start injector is ...er .... stuffed (sprays fuel out the back of it - into the engine bay - if I trigger it manually. But no fuel comes out the front! 😂 ) I'm just about to go and pick up a good second hand one from my brother (thanks bro!), Haven't yet tested the thermo-time switch but I have been told in the past by a reliable source that the cold start injector will only inject fuel at very low temps (close to/below zero) and not at the temp ranges listed in the manual. Can anyone confirm which info is correct?

Better still, does anyone have an EFI Bay window Kombi that they would be willing to disconnect the cold start injector (just unplug the electrical connector from the back of it) and try to start it cold? I would just like to know if it struggles to start when the injector is disconnected....? This would answer all sorts of questions for me.

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 · 21 Jan 2010, 10:52 am

#758633

Hi Volks,

I finally found the time to fit the known-to-be-good cold start valve (injector) to my motor. An air leak caused by some old sealant made me do the job twice - properly the second time 😀

I have tested it for the last two days and I am happy to report that it starts on about the 3rd compression every time when cold. Far better than it has ever been! 🙂

Looks like the temp figures for the thermo-time switch that are published in the manual are correct - the cold start injector does appear to fire at temps up to either 35 deg C or 50 deg C (depending on your thermo-time switch) when the starter is operating.

I am still going to swap the Temp-sender II over to the new one (when I find it) as the cold idle is still a little low for my liking, but I won't be too concerned if there is no change as the problem really isn't that bad.

Thanks to everyone who took the time to reply - I now have a much better understanding of how the factory EFI system works ... and a Kombi that starts first go all the time! 😀

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. 🙂

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 21 Jan 2010, 12:24 pm

#758643

Well done 👍

Futue te ipsum!!!