Pull the vac line off the back of the IM, put the end in a bottle and crank the engine. Or take it off and try blowing through the vac line.
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Disconnect vacuum pipe and see if fuel comes out when starting car. Obviously block of vacuum pipe to intake manifold.
Next disconnect n80 valve between cannister and valve. Then connect the n80 side to a boost gauge take car for a quick drive and see if it makes positive pressure if so the one way valve is shot.
From your description I would say the second one is your issue. As you make boost you pressurise the fuel tank. Fuel pressure regulator can't return to tank you flood your engine with fuel as you can't regulate fuel pressure.UrS6 Stroker + HTA3586 =
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Nice, I will try these out.
Q: Can I just block the valve off?Go Holset or Go RS4Comment
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the dead FPR sounds plausible. yes, this has happened to me, the membrane in there tears, and allows gas to flow into the vacuum nipple. easy to test with a mightyvac (pull a vacuum on the nipple, it should hold that vacuum). or run the engine with the vacuum line disconnected. if its failed, gas will shoot out of the nipple (sounds like some crazy car related porn movie!)Marc Swanson
Proprietor, EFI Express
95.5 //S6 Avant
90' Coupe Quattro V8 4.2L twin turbo
93' //S4
83' UrQ
97' F250 7.3 diesel
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I will do it ASAP and report back!Go Holset or Go RS4Comment
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Today I had a quick try on the car and pulled the vac line off the FPR and started the engine. Started normally (because of VEMS it doesnt not care if A vac line is pulling air). No fuel came out of the FPR nipple.
That leaves us now with the N80 valve? As I understand from what UrS4Boy posted here the N80 valve has an one way valve within. So if I remove the line to the IM and pressure test it it should hold right?
I asked by at the gas station the guy that fills the car and he said he pressed the small button at the gas tank entry so that he can top up the car with fuel. Can it be that with that he filled up the evaporative line and this somehow released a reaction?Last edited by Billman; 25 June 2012, 09:29.Go Holset or Go RS4Comment
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So, FPR seems Ok and as always sometimes a stupid thing is accountable for stress.
The ECU boost pipe was almost off. That would for sure explains the rich running since I was driving off boost and the ECU was thinking that it was on. However I am going to check it out on the streets around my home.
About the overflow issue I still don't have an explanation.
Had the car idling and city driving for 20 minutes at full temp and the lambda and EGO correction was perfect.Go Holset or Go RS4Comment
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Billman,I have 3 n80 valves.one is stock ,one purchased as used,the other is brand new.
2 of the old n80 can blow by and the new one can be holding the pressure on both side.
If you still have not wired the additinal output signal to control the n80 from vems.i think
You just simply block it off.one of a few I5 from Asia.Comment
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I will remove mine to see if I can blow through.
Can I simply use only a one way valve there so that the tank is on vacuum or will it run rich all the time?Go Holset or Go RS4Comment
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N80 also ok. blows only in one way (right one).Go Holset or Go RS4Comment
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Did an 1 hour drive today and everything seemed fine....apparently the pressure line caused all this. As for the overflow of the tank most probably too much fuel with the pressing of the button inside the tank entrance.Go Holset or Go RS4Comment
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Trying to source this issue I measured the fuel pressure next to the pump (outside the tank and before the filter). I know this is not the best location but was the easiest.
I have a 3.8 FPR and it measured 4.4-4.5 bar.
Anyone else has experience there? Did someone measure pressure at that point?
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