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 andytlr
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| posted on June 7th, 2005 at 06:48 PM |
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Running better and worse
Hopefully someone can answer this question. Sure one of the experts can.
When my car doesn't have much fuel in it, it runs OK. But when it has a full tank of fuel it runs great...
Any ideas why? |
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wezley
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| posted on June 7th, 2005 at 07:04 PM |
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Ok I really know SFA about engines but maybe there is some residue that has built up in the fuel tank over the years, when the fuel gets low, some of
it starts to block??
hehe, don;t take my word for it though..
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 Bizarre
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| posted on June 7th, 2005 at 07:41 PM |
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Wez - i think you been learing stuff hanging round here.
Andy - that would be the first thing i do. A REAL good clean of the tank and a change of filters
Futue te ipsum!!!
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andytlr
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| posted on June 7th, 2005 at 07:47 PM |
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Any idea how to get into the fuel tank? And is it possible to save the fuel in the tank or do you suggest doing it when it is almost empty then
draining it completely? |
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Bizarre
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| posted on June 7th, 2005 at 08:28 PM |
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http://www.vw-resource.com/fuel_tank.html
have a read here
(save this site - it REALLY does answer most questions)
Futue te ipsum!!!
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andytlr
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| posted on June 7th, 2005 at 10:09 PM |
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Will do. Thanks all. |
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General_Failure
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| posted on June 7th, 2005 at 11:49 PM |
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my car does that. I thought it was the extra pressure from the weight of the fuel making it run better. That's based on absolutely no factual
information by the way.
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
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andytlr
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| posted on June 8th, 2005 at 12:03 AM |
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I would have thought that. Except the fuel tank is at the front, and it is a rear wheel drive. So doubt it would make that much difference.
I read how to do the removal and refurbishment of the fuel tank. Sounds like something I could do but need to buy a lot of replacement seals and the
like. Plus it sounds pretty time consuming with a lot of waiting around for stuff to dry. But a man's got to do what a man's got to do.
I also read the one about replacing the fuel filter(s). Which sounds like it might be an idea.
What I don't understand with what Wez & Bizarre said is that why would the rust and what have you only try and get through the fuel line when it
is getting lower in fuel? Wouldn't it always try and get through?
Either way, I'm on uni holidays at the moment and not working a lot so I should try and get it done in the near future.
If I opened up the fuel tank where the float goes in when it was almost empty would I be able to use a torch to see what the condition is like to make
sure it is the problem before I go through the whole process and find out it did bugger all? |
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General_Failure
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| posted on June 8th, 2005 at 01:04 AM |
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This might sound a shade paranoid, but if you really want to look inside the tank disconnect your battery, and put the torch in a sealed clear plastic
bag. Petrol vapour can go boom.
Another easy way to tell if your car is sucking crud is to check the filter if you have a paper one. I always have crud residue in mine. I really need
to clean the tank.
My carby float tanks had over 1/2 cm of mud in them too. Yuck!
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
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andytlr
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| posted on June 8th, 2005 at 01:17 AM |
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I might get under the car tomorrow and check that filter. Then maybe replace both of them before I do the fuel tank. But it sounds like because it
only runs shit when its low on fuel that it's probably the tank. Looks like were both up for this job. |
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andytlr
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| posted on June 13th, 2005 at 04:22 PM |
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I looked under the car. I couldn't find a fuel filter anywhere... But I replaced the filter next to the engine. Cut the old one open and it didn't
look too bad but it was far from perfect. Seemed to run nicely when I started it up even though it was cold. Although it does have just about a full
tank of fuel so will see what happens when it empties a bit.
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76camper
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| posted on June 13th, 2005 at 05:28 PM |
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might be a pressure thing? As tank gets lower there is less fuel pressure. Dodgey fuel pump???? |
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andytlr
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| posted on June 13th, 2005 at 05:59 PM |
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Nah, it got a new fuel pump for the roadworthy just before I bought it.
Just have to wait and see if it still runs well when closer to empty. The filter may have fixed it. I put in new spark plugs as well which made it
generally run a bit smoother so it may just have been a combination of little problems.
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bajachris88
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| posted on June 13th, 2005 at 07:17 PM |
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Yeah, its probably just the rubbish in the tank then. Like you said, rubbish would be going through the engine, even when full. But (depends on the
rubbish) if the rubbish is willing to float, it won't come down and get sucked into the engine until the level of petrol in the tank becomes low.
And as fuel is sucked out of the tank by the engine, the rubbish in there is going to come together and get more concentrated as the petrol is gone,
and therefore collects up to become of higher concentration. Therefore, the < amount of fuel left, the > the concentration of rubbish in the
tank, therefore the > amount of rubbish to get sucked in.
Well, thats just a thought, hopefully you might be able to get my drift.
Wateva way it is mate, I hope u get on top of it. Goodluck, im sure u will. 
Oh, and the full tank would increase the pressure of the fuel going into the engine, therefore its easier to suck in. And when the level of fuel
decreases, there is virtually little or perhaps no pressure and the pump has to do all the work instead. So having a fuel engine helps it go into the
engine, not sure how well though. But I would be pretty confident to say that it would have some form of effect.
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andytlr
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| posted on June 13th, 2005 at 07:50 PM |
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Yeah, its not really a major issue. I just noticed it was slightly better when full. So I'll just see what happens. But I do understand what you
mean, I didn't think about it floating before.
cheers
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76camper
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| posted on June 13th, 2005 at 08:18 PM |
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The pressure will change quite alot, but the fuel pump should even the pressure out over the range of the tank being full then going empty. If you are
using ur car as a daily driver, how much crap can be in the fuel tank??? If the prob stay around its most likely a pressure thing. |
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andytlr
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| posted on June 13th, 2005 at 09:05 PM |
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Well I am using it as a daily driver now, but it has rarely been driven in the last 3 or so years before I bought it.
One other thing that I thought would make no difference but might. When I was doing some rewiring in the boot I noticed a small amount of petrol
leaking from out of the cap in the centre of the fuel tank. There was 5 screws on it so I tightened them up. They all required about three turns to be
tight. But the ability for air to leak into the tank would make absolutely no difference would it? I don't really understand how it works, but I
figure it probably doesn't. Air could probably get in through the fuel cap quite easily anyway.
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