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YellowPanda

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• Mar 14, 2011

• #1

Hi there,

I have a 2004 Panda 1.2 that misfires but the odd thing is it only does so when cruising (hot or cold) and only when the fuel tank is full or nearly full. Once the tank has gone down to about 3/4 it's fine. I've checked over the forums here but none of the usual circumstances seem to apply.

Any ideas anyone?

 

R1NGA

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• Mar 14, 2011

• #2

I would check the tank vent pipes, as if they're blocked the fuel delivery could be affected. 1.2 is what they call a 'dead head' system, in that there's no return to the tank - it's a one-way delivery. The Blue (I think) hose on the inlet manifold is the breather/vapour return to the emissions system. Suspect an issue in this area.

Phil

 

Pandablues

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• Mar 14, 2011

• #3

Find a big car park and try driving with fuel cap off. If it improves, check the filler breather for blockage. Else........have somebody check fuel pressure?

 

Last edited: Mar 14, 2011

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YellowPanda

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• Mar 15, 2011

• #4

Thanks for the replies, I'll definitely check out the possible pipe blockage, not so keen on driving about with the filer cap off (can see the logic though) as it only does it when the tank is full or nearly so so I'd likely lose some fuel to spillage.

I'll post again when I've checked it out and thanks again.

 

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MintSauce

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• Jan 30, 2012

• #5

ok so I realise that this is a very old thread. However, has anyone else had this and did they get to the bottom of it? I am having the same problem (2005 Eleganza 1.2) and it does seem to be related to how much fuel is in the tank

Any suggestions of how to check the pipes are ok? Can this be done under bonnet or does it need ramps? I don't have access to a garage at the moment so can only check stuff that can be done at the side of the road with minimal tools

I do have eLearn so am looking at that at the moment and it does suggest checking the vapour recovery system..

Cheers.

 

R1NGA

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• Jan 31, 2012

• #6

I suspect the easiest test is to drive (carefully) without the filler cap on, or perhaps just loosely on, and see if that makes a difference. When the tank is full there's precious little air in the tank and if the breathers are blocked there'll be a bigger pressure-drop effect than if it was say half empty. You'll see on eLearn that there's a carbon vapour canister somewhere in the mix (near the tank I think) and this might need checking too. You probably will need acess to a ramp in the end mind.

 

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MintSauce

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• Feb 5, 2012

• #7

Well I have tried driving without the filler cap locked shut - no apparent difference.

I also took the rear offside wheel off to have a look. The carbon filter canister thing was caked with years of mud/grime and there's a breather on top of that too. Cleaned off the 3 inches of solid muck stuck all around it and it seemed a bit better but once the car was warmed up the problem was back.

So I'm not sure what else I can check at the side of the road. eLearn shows a couple more valves on top of the fuel tank, then there's the submersed pump/filter itself..

Economy suffers greatly until it's down to 1/4 tank and running properly again too. No CEL or any fault codes stored either by the way.

Hey ho, shouldn't complain too much I guess, 76000 miles and no major faults until now.