fuel problems with breather

Discussion relating to the Scirocco 1982-1991 - - please ask technical questions in the technical/trouble shooting section
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Nuckleduster
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fuel problems with breather

Post by Nuckleduster »

Hi all,
During this hot weather I am having trouble with the car cutting out/electric fuel pump going nuts. I have found that the tank is not venting properly.
When I take the fuel cap off I get a sudden inrush of air and the car will start and run properly.Obviously the tank is not venting properly especially with low fuel in the tank during the hot weather.
My question is where can I get a new vent valve from or can it be repiped to work without one as the valve serves to stop fuel spill when upside down and vent the tank right side up.I am going to shove an air line up the breather pipes to check for any blockage but after 29 years the valve might be knackered.
Best wishes
Gerry


91 Scirocco Scala 1.8 inj rolling shell gone but not forgotten
90 Scirocco Scala 1.8 inj Colour Dark Metalic Green daily ride
Vw MK4 Golf Estate @180bhp Daily working car--Silver
94 Corrado 2.9 VR6 Metalic purple--gone to Manchester--
Nuckleduster
Posts: 61
Joined: Sun Jun 28, 2015 6:36 pm
fill in the right answer: 15

Re: fuel problems with breather

Post by Nuckleduster »

Just to add a comment the MOT examiner said that the car would stall and be a pig to start when he tested it,but at the time I thought that he was pissed off with setting the alarm off and the immobiliser was kicking in--never had any problems before MOT day.By the way it passed!!!!


91 Scirocco Scala 1.8 inj rolling shell gone but not forgotten
90 Scirocco Scala 1.8 inj Colour Dark Metalic Green daily ride
Vw MK4 Golf Estate @180bhp Daily working car--Silver
94 Corrado 2.9 VR6 Metalic purple--gone to Manchester--
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essextom
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Re: fuel problems with breather

Post by essextom »

I’d double check the valve is orientated correctly first, and that there are no kinks in the breather pipes.


mark1gls
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Re: fuel problems with breather

Post by mark1gls »

Try not to let the fuel go below 1/4 tank as the petrol cools the lift pump in tank.


Mk1 78 Scirocco GLS 1.6 FR, weekend toy.
Mk1 88 Golf GTi cabriolet 1.8 DX. Daily drive.
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Nuckleduster
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Joined: Sun Jun 28, 2015 6:36 pm
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Re: fuel problems with breather

Post by Nuckleduster »

Hi all,
Thanks for the replies, I have had all the pipes off and shoved an air line up all the pipes to check for blockages also fitted a replacement valve salvaged from the scrapped rocco. I have also checked the pipe runs to make sure they are not kinked. Haven`t found anything definite that would cause the problems. Only thing that came to light was with the fuel cap off, the fuel gauge reads lower than when its on--strange!!
Anyway I have put 35 litres of fuel in and the car has behaved itself since--Mark`s point re cooling the tank pump by keeping the fuel level up has made me think. The external fuel pump is much quieter and the cutting out has stopped occuring.I was about to fit a new rotary pump but have put it off for the time being.
Can someone confirm that the fuel cap is a non vented one as I have 2 identical orrynes and they both appear to be non vented and are originals--one from the 89 model scala and the other from the 91scala that has gone to the graveyard.
My wife took her pride and joy out and has reported back that it is running really well so I`m keeping fingers crossed but I would love a definitive answer as it will niggle me untill I find a reason.
Best wishes
Gerry
Not a footie fan but COME ON ENGLAND!!!!!!


91 Scirocco Scala 1.8 inj rolling shell gone but not forgotten
90 Scirocco Scala 1.8 inj Colour Dark Metalic Green daily ride
Vw MK4 Golf Estate @180bhp Daily working car--Silver
94 Corrado 2.9 VR6 Metalic purple--gone to Manchester--
mark1gls
Posts: 3954
Joined: Thu Apr 02, 2009 9:28 pm
fill in the right answer: 10
Location: Somerset

Re: fuel problems with breather

Post by mark1gls »

Non vented caps for fuel injected cars, vented cap for carb cars...

You will get some pressure build up when you fill the tank then run it down, a slight whoosh when opening the petrol cap to fill it up again is fairly normal.


Mk1 78 Scirocco GLS 1.6 FR, weekend toy.
Mk1 88 Golf GTi cabriolet 1.8 DX. Daily drive.
Membership No. 323
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