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dan, VW Technician
Category: VW
Satisfied Customers: 420
Experience:  ase master tech, vw specialist
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Customer Question

I have a vw polo 1.0L "R" reg 1997. and the bugger won't start. I have changed plugs and they all spark when placed on the manifold. There is fuel present at the injector manifold and pumps when ignition turned on. I checked all the connections to the injectors and they have 12V present for about one second when the ignition is switched on and 12V constant when engine turned over. I also found what appears to be a air valve connected via a hose to a small expansion tank behind the offside headlamp. This valve has 12V when ignition is switched on but I can't blow air through it. Please Help.
Submitted: 8 years ago.
Category: VW
Expert:  dan replied 8 years ago.

It seems like you have covered the basics with fuel and spark. The next logical thing to test is timing. I do not know what this vacuum reservoir that you are speeking off is but that valve my be normally open and powered shut. Oh yeah, just because you have fuel pressure doesn't;t mean you have injector that are opening be sure to test these during your diagnosis.


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Customer: replied 8 years ago.
The apparent air valve does not open in either state. I can only presume that it allows air from the fuel tank to flow to the inlet manifold to aid starting in cold weather. If this failed it may make the engine difficult to start but this engine does not attempt to fire.
Expert:  dan replied 8 years ago.

This valve sounds like the evaporative emissions system and the valve that you are describing sounds like the canister purge valve the is probably ground switched from the ecm it scavenges fuel tank fumes and puts them back into the combustion chamber via the intake. Check timing and injector pulse.


I hope that my answer was helpful. PLEASE hit ACCEPT. Thank you.



Customer: replied 8 years ago.

problem partially resolved. Did not look at timing as all plugs firing when placed on the manifold 1-3-4-2. After removing all injectors and watching them operate and spray fuel (which I presumed was the case), then checked the air intake manifold wich appeared to be working, however the engine fired up when this was disconnected and was running ok. I heard a few missfires so I will be changing all the HT leads, dizzy cap and rotor. I will also be seeking a recon air intake manifold.