Backfiring and stalling.

[Dave307]

Hi all.

Just wondered if anyone can help.
My van has started to backfire and stutter in low gears when I accelerate. It is then cutting out and stalling when I put my foot on the clutch.
It then starts up fine and idles ok.
It only seems to do it on slow back roads were I have to change gear alot.
If I get on on the open road she runs fine.

Any ideas. I have checked and the oil and water are ok.
I ran out of fuel yesterday and she did it after that. I have filled her up and shoved some redex in her and she ran fine in the duel carriageway home however again this morning going over the moor she started coughing and spluttering again.

[ermie571]

filters.
Carb.

dirt in both I expect

replace in line fuel filter?

Em
xx

[CovKid]

Agree. If you ran out of fuel, the last dregs were probably full of crud. Change fuel filter and if its a 1.9DG, clean out the small cone filter hidden away inside brass fuel inlet pipe on carb (see WIKI). If its still playing up you'll need to clean out carb properly.

[BOXY]

When you change the in-line fuel filter you normally need to clamp the flexi pipe coming out of the tank to stop petrol pi**ing everywhere. Before you fit the new filter, let the clamp loose with the flexi in a jam jar to check that petrol is able to flow from the tank. By running the petrol low you might not only have blocked the fuel filter, but the outlet of the tank might be blocked as well. If the petrol only trickles out you might need to blow the outlet to clear it.

[Dave307]

Okay Guys and Girls.
An update.

I have just driven her home from when and when cold she ran like a dream no backfiring no stalling nothing. However when she got up to warm ie needle just past the half way point she then became a pig. She stalls when I dump the clutch. The oil light flashes on first the battery lightand she cuts out. She does bump whlie on the move and if stopped she will fire up straight away.

Once home I sat her on the driveway at tick over and she was fine. I then pressed the accelerator a little and she coughed and spluttered and stalled. I restarted her straight away with no issue pressed the accerator hard and she revved up fine.

The problem appears to be when the accelerator is only pressed a little ie to maintain speed rather than increase.
I'm now gonna replace the online fuel filter and make sure there are no blocks in the line.
Anymore ideas peeps would be great as a bit stuck now.

[ghost123uk]

Assuming this is a flat 4 petrol engine with a carb (ie not fuel injected 2.1) then this sounds like the classic symptoms of a blocked primary main jet in the carb. (the main jet underneath the smaller of the 2 choke chambers)

You would need to split the carb to check this = dead easy, the air filter, a fuel pipe, a wire or 2, a throttle cable, the water pipes for the auto choke, 4 cross head screws and the top of the carb comes off. Then check that main jet and the other jets, DO NOT poke wire through them, blow or use a bristle from a yard brush (or similar softish poker).

The only problem you are likely to come across is the gasket often gets damaged on splitting the carb so you will very likely need to source one first (or be off the road until you get one), btw, DO NOT use ANY gasket goo on the carb !

Don't forget to bleed the cooling system after having had the water pipes off the auto choke unit.

p.s. = source = had this on our T25 last year and our Scirocco (same carb) last week!
Where these bits of black gunge come from is a mystery as both vehicles had good fuel filters.

E D I T = gasket from = http://www.ovalracingforums.co.uk/viewt ... f=6&t=7992" onclick="window.open(this.href);return false;
We stock the top gasket for the pieburg = http://www.atspeedracing.co.uk" onclick="window.open(this.href);return false; - tel: 01268 773377
And probably Brickwerks too of course (tho they may only do the full service kit)

[edoh]

from the (wicked) wiki -
Carburettor causes
Weak misfire/hesitation Air leaks anywhere between carb and cylinder (flanges/manifolds, vacuum pipes etc)
Fuel starvation (fuel filter, tank feed blockage, pump failing)
Grossly over fuelling (snatching, bucking, kangarooing) - temp sender/blocked air filter, stuck choke etc

[ghost123uk]

from the (wicked) wiki -
Carburettor causes
Fuel starvation (fuel filter, tank feed blockage, pump failing)

Fuel starvation (fuel filter, tank feed blockage, pump failing) or a blocked primary main jet

[edoh]

sounds good to me

[ghost123uk]

Can't wait to find out what it turns out to be

We might all be wrong

[Dave307]

Gonna check the fuel filters and lines tomorrow. Gonna order a gasket just incase I get through everything and have to strip the carb off. Will keep you posted.
Any more ideas keep them coming.

What puzzles me is the fact that it's fine when cold.

[kevtherev]

weak mixture when accelerating is caused by a few things on a pierburg 2e3
1, the transfer jet is blocked or accelerator pump diaphragm holed
2, water ingress into the float bowl
3, Air leaking into the induction side


Water if it were in the tank would be drawn into the float bowl and sit there till it was removed
it would sit in the transfer jet pump too

when cold the the fuel entering the engine is enriched so any deficiencies in mixture is cancelled out.

my money is on an air leak or water

[ghost123uk]

He he, from the symptoms I am going to stick my neck out and go for a blocked / obstructed primary main jet.

£5 to the charity of the OP's choice

[CovKid]

And don't waste money on precut gaskets. Money for old rope that is. Any motorcycle shop or decent motor factors should have gasket paper - easily cut with a craft knife and often better quality than the precut ones I find.

[ghost123uk]

Umm, Rather you than me, OK with BSA chaincase gaskets, but a Pierburg top gasket is a delicate work of art(ish)