No fuel after stopping when hot

[JamiePz]

Hello all,

Im a proud owner of a 1985 autohomes t25 1.9dg wbx. Love it.
The information on this forum has successfully guided to solutions to a number of issues to date but I am now faced with one i can't seem to find an answer to.

My bus runs well but an intermittent fault has started to become more regular and i am stumped as to what to do. It satrts from cold first time every time. I then can drive for as far as i want / need without issue. The issue is If i have to stop to put fuel in or nip into a shop after it has reached normal running temperature. Again it will start no problem but only travel a couple of hundred meters before it cuts out and stops. I figured out that when this happens no fuel is in the fuel line or carb.... suggesting it had been "sucked back" into the tank whilst i was in said shop or fuel station? possible?. I fitted a hand primer with a one way valve in it close to the carb so i could pump the fuel back when it happened.... this works but its beginning to get on my wick because of having to empty the boot to get to it. Once primed it starts and runs again. Most of the time it again will work fine until i stop again. Sometimes i have to wait until its cooled down a bit and then its fine.

Additionally, when driven to work it gets to running temp (work is 25 miles away) and then i leave it all day whilst working. When i get back in it it starts and runs fine.... no priming required.

The fuel line is in one piece and new (apart from the addition of the hand primer and a filter which is positioned at the fuel tank.... and newish)
the fuel pump is new

this is an issue i have had for a number of months . I have not serviced the carb or had it off.

Any ideas would be gratefully received.

kind regards

Jamie

[New Kentish Campers]

I'd try taking it for a run, with some tools at the ready, and park it up in a lay-by or similar and wait for it to play up and then take the top of the carb off to see what the fuel lever is in the float chamber. I dont know if there's a non-return valve or not though but If there isn't any fuel present then perhaps its either leaked out - which you would smell/see anyway or isn't getting enough there in the first place. You say you replaced the pump but what about the operating rod that works it. They are good at wearing down so the pump isn't getting a full stroke and in turn pumping enough fuel to the carb. I think, if memory serves, it should measure 100mm, but check that in the wiki. And replacing the carb's gasket once you've finished with taking the top off isn't a bad idea either.

[JamiePz]

Thanks for the reply. i didn't replace the pushrod when i put the new pump on, but have just checked it. It's half a mm short of 100mm.
Do you think this is significant? Also not sure how this would relate to being warm?

much appreciated

jamie

[New Kentish Campers]

I would have thought that it wouldn't be, no. But my point was that it's supplying fuel to the carb correctly.

Could be the choke mech is sticking so as to flood the engine.With the engine nice and hot, the choke flap should be fully open, i.e up at a right angle to the carb body. If at all closed, it will enrich the fuel mixture to give starting problems when hot. When driving, the fuel will burn off and you might be seeing black smoke from the exhaust? its not so much an issue when cold as the engine would need more fuel anyway.
Also check the float mechanism to make sure it's not jamming and over-fuelling the engine [mine did just that and made the van un-drivable, unless driving at over 50 mph to burn it off]

[JamiePz]

Thanks again. I'm quite sure its not flooding but could be wrong! I also think the choke is operating as it should (flap open when cold and nearly closed when warm... I've watched this happen and the choke does switch off with a blip of the throttle when warm). No smoke. maybe i should take it, encourage it to present the issue and then look at the choke to see if it is still off?

When it has cut out following a brief stop whilst at running temp it will fire on carb cleaner... It will also fire when i've manually pumped fuel to the carb via the hand primer..

cheers for you thoughts. Would appreciate any others.....

Jamie

[New Kentish Campers]

No, the flap should be open when hot and closed when cold. If you are correct [not got it back to front when typing your reply ] then thats likely the problem, i.e sticking choke mechanism and over-fuelling the engine. Once the engine has reached its running temp then the flap should be open, i.e allowing more air into the engine.
When you are putting carb cleaning fluid down the intake or manually priming the carb, thats still with the carb's top on, right? I mean, you still dont know if there's fuel inside the carb's float chamber?

[JamiePz]

yes.. a mistake typing.

I see what you saying. But, it stops after a couple of hundred yards following a brief refueling type situation. It starts and runs fine for those couple of hundred yards. So my layman's mind is saying that residual fuel is sat in the carb and that is whats getting me the few yards... when its used, no new fuel is coming through and it cuts out. Obviously i know this could be complete rubbish. I push a pen for a living so this really is not my area of expertise!!!

cheers

Jamie

[New Kentish Campers]

Ok. Drive it, let it get hot [temp gauge needle sitting on or just over the red warning lamp] stop the engine and try to restart it. Dont immediately pump the throttle pedal as that might flood the engine. If it wont start, try priming it with petrol as you mention and restart the engine.If it runs then fuel cannot be reaching the engine the conventional way. Then have to hand the tools required to take the top of the carb off. Let it run to full temp if its cooled down at all, switch it off and remove the air cleaner. The choke flap should be open, fully. Take the top of the carb off and look inside and look to see that the float chamber reservoir is full and that the float can travel up and down smoothly. Be very careful of allowing petrol dripping onto a hot exhaust when doing this

If fuel is present, then your pump is working properly and the float itself is shutting off, i.e not overfuelling the engine. Then try activating by hand, the throttle linkage so that you should be able so see neat fuel being squirted down the venturi and into the engine. That is telling you that fuel is going into the engine. So really, if that is working, then the engine should run.

If there is only a little fuel in the float chamber, check the inlet filter, where the outlet pipe from the pump goes to the carb. There's a little conical shaped filter in there that can get blocked. And of course, all your fuel lines and other filters need to be nice and clean too. Check for any signs of dirt or sediment in the carb itself that could block fuel flow.

I might be wrong, and this is a long shot but I think there is a carb heater fitted? Could be that its staying on all the time and evaporating the fuel after the engines turned off, from it's residual heat perhaps? And make sure no fuel lines are near a heat source as that, apart from being a fire hazard, could evaporate the fuel. I hope that helps, though I'm out of ideas now so I hope others can step in if these ideas don't work

[JamiePz]

Thank you for this. I will try tomorrow.

This afternoon i went to the shop and when i pulled away it cut out. It was still warm. I took the air intake off the top of the carb and the choke flap was indeed fully open. it would start so i primed it, started it and then closed the choke flap and the revs increased as you would expect....let it open again and they dropped to idle.
I then drove home all ok.

Could i have seen if the float was full just with the air intake off? or would I have to split the carb? (trying not to sound like a complete div....)

really appreciate the effort and advice and will let you know tomorrow.

cheers

Jamie

[JamiePz]

Right. Just been for a run and got it hot it started and ran perfectly. drove for 10 miles ish. Stopped for a minute and then drove off. As expected it cut out shortly afterwards.
I took the top of the carb off and the float chamber only had a little bit of fuel in it and the choke flap was completely open..... I then pumped fuel with the hand primer and it took 3 pumps before fuel came out of the exit pipe of the fuel pump. i then connected the pipe to the carb and gave it another pump. The chamber was then full and bus ran ok.

I couldn't get the chronicle shaped filter out of the inlet to the carb(how is this done?) but did spray a bit of carb cleaner in it. The float itself seems to move freely enough.

ideas appreciated

Jamie

[New Kentish Campers]

So, it would seem then that the van is using what's in the float chamber before dying out. By the way, I'm assuming you have a 2E3 carb fitted?? if not then much of what's been said shall still apply, save for the inlet filter, which could be different, I dont know

I'm wondering, unless the inlet fuel filter isn't blocked, [click the red highlighted link; filter is shown as number 2, here]: http://onemanspanner.wordpress.com/2011 ... w-vanagon/" onclick="window.open(this.href);return false; if your pump is working properly.

Try disconnecting the outlet pipe from the pump to carb intake and extending the pipe so that you can safely put the end into say an old milk bottle. Ideally, get some help when doing this. Remove the rotor arm from the distributor beforehand, so the engine cannot spark & run the engine with what fuel is still in it. Crank the engine over and watch to see that the pump is delivering fuel in equal amounts as the engine spins over. If it does, then the pump is doing its job[ you have checked the stroke bar too, which was nigh 100mm long] so if fuel is present, then its not entering the carb, i.e blocked inlet filter. To inspect this, use a 2" or so screw and gently place it inside and turn it so it enters the filter a little and pull the filter out. Not a bad idea to buy a new one, particularly if the filter has been damaged before by somebody who used brute force to pull it out With luck, it will be partially blocked and thus starving fuel to the carb.

Another thought: If fuel isn't pumping properly, then it could be that the supply TO the pump via in-line filter from the tank is blocked, i.e not allowing fuel to the pump. or the tank to pump hoses have begun to collapse internally [not uncommon with these bio-petrols]. If the hoses have never been changed, then do that sooner rather than later - Brickwerks sell all that you will need. If this still doesn't alter anything, then look at the pipework on the fuel filler neck and the grommets on top of the fuel tank. Basically, the fuel tank needs to be sound throughout so neat fuel can be sucked up to the pump with nothing else [air] in it.

Once all this is checked and done, I can't see any reason why it wouldn't then run. I am only speaking from my own experiences of my own van which used to run terribly until I sought advice on this forum so there are others who will be able to offer more advice.

lastly, read though the wiki to see how the carb needs to be set-up for correct choke operation, especially with winter not too far away. You may as well iron out any other issues whilst you have everything apart.

I hope this helps you.

[Miles]

Jamie
This is an old post but I hope you take a look here from time to time. Did you ever establish what was wrong ? I have very similar symptoms and I can't figure out what is happening so any help from you or anyone else would be greatly appreciated.
My van starts from cold very well, but has developed an intermittent fuelling problem when hot. It has happened two or three times so far, at intervals of hundreds of miles, when the engine is hot, or warm. The first time I think it happened, it sorted itself before I got to look for the problem : we arrived to check-in for the Newhaven ferry, and after sitting waiting for maybe half an hour we started to load. The engine started fine but I could not hear it because of the monster coach-size motor-home in front of us (what are they for?) and after shuffling forwards for a few minutes we started kangaroo hopping as the engine started to run very lumpily. After a little revving it cleared and took us off to France covering 250 miles, with no trouble except for the engine cutting momentarily - again after a half-hour stop. This was so brief that I used our momentum to bump start and no-one even noticed. The next time, and the first time I got to find out a bit more about what was happening, was after an MOT test when the engine had been running at standstill for quite a while (it got quite hot and dumped half a pint of water), as I was driving off the engine stalled then fired intermittently as I cranked it, then wouldn't fire at all. This was a good place to break down, and soon we noticed that there was almost no fuel in the filter which I put in a year or two ago between the pump and the carb. The engined fired with a squirt of something into the airbox, then seemed to fuel itself and away we went. I couldn't do anything about it as we had to go to Bristol next day (350 mile round trip). It did the same thing again once there, after a half-hour stop. It started fine and I drove a few hundered yards, then lumpy running, stopped, occasional firing on cranking, then no firing. I got into the engine bay and sure enough the fuel filter looked empty, so I took the hose off between the filter and the carb, and sucked. While I was sucking I noticed a very faint hissing bubbling noise like air getting in, somewhere around the fuel pump. Once the filter was near-full and re-connected, the engine ran fine, and the next day as well for the return journey, which was 165 miles of motorway quite heavily laden, during which it was quite happy doing 60mph up hills. So the pump must be pumping enough fuel while running normally. Besides the engine being hot then rested for a short while, the only other common circumstance is I think it does this when the fuel is a little on the low side, but still not into the red. Another symptom which might have something to do with this is that ever since I got the van about 3 years ago, it starts well when cold, whatever the air temperature, and it starts well when hot, for example after a re-fuelling stop, but it doesn't like starting once hot and then left for half an hour, and requires a bit of welly, wherupon in starts after turning over for 10 seconds or so. These are the same conditions as when it does its fuel starvation thing. Is it my auto-choke? Might I have an air leak in the fuel pump spacer gasket? Any ideas would be very welcome.

Miles
1.9 DG with mechanical fuel pump

[Ian and Lins]

Got the same problem with ours; only happens once a year and Saturday was this years occasion. Fule was not being pumped through the mechanical fuel pump (a little over a year old) but could be sucked through. Am getting a new push rod as it's only a few quid and will measure the old one when I take it out.
And on both occasions it happened in a Morrison's car park but I don't think that was the cause!