Poor warm starting S2 ABY

[prj]

Looks like a fuel problem to me also from the video.
Insufficient fuel pressure, which slowly builds.

[hermanio]

ok, im going to place an extra check valve just after the fuel pump and see if it works, it wont do any harm..

[hermanio]

i placed a check valve just behind the fuel pump today, but it didnt solve the problem. but i think i found the problem because when i shut down the engine and disconnect the return line at the pump, there is no fuel coming out if it (how it should be). but after 5 minutes, fuel slowly flows out of the return line. my conslusion is that the fuel pressure regulator won't hold pressure due to the heat and fuel slowly flows back in the tank. is this plausable ?

[hermanio]

is there a way to test the diaphragm in the FPR ?

[hermanio]

This isn't normal, is it ?

[hermanio]

does anyone know if its normal for fuel to drain back to the tank (this fast) when the engine is shut of, as seen in the video ?

[Bowlerwell]

Unfortunately I can't help, but I'm interested in what anyone else has to say...

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[UrS4boy]

i placed a check valve just behind the fuel pump today, but it didnt solve the problem. but i think i found the problem because when i shut down the engine and disconnect the return line at the pump, there is no fuel coming out if it (how it should be). but after 5 minutes, fuel slowly flows out of the return line. my conslusion is that the fuel pressure regulator won't hold pressure due to the heat and fuel slowly flows back in the tank. is this plausable ?

On shut down, the fuel pressure regulator (FPR) spring should seal the return closed, i.e. maintain pressure in the fuel rail until the next start up. If the FPR is not making this seal, the fuel in the fuel rail will drain back into the fuel tank. As a result, the next time an attempt at starting the engine is made, the engine will not start until the fuel rail has been refilled and repressurized. Suggest you replace your FPR.

Here is some FPR info to ponder:

http://forums.quattroworld.com/s4s6/msgs/21108.phtml

[twoqu]

You are going to struggle to get a definitive answer without hooking up a pressure gauge. The VAG one is nice as it has a tap that you can open or close which allows you to eliminate the fuel pumpcheck valve.
A few possibilities:
A leak somewhere in the pipework.
The injectors leak.
The non return valve.
The fuel pressure regulator.
The spec for the fuel holding pressure is 3.8 bar with a hot engine, 10 mins after shutdown. For a cold engine its 3.5 bar. The difference is due to the expansion of the fuel.
You have suggested that the engine feel rich which might indicate that one or more of the injectors are leaking, but again the only solution would be to have them professionally tested unless you want to risk rigging up a fire hazard in your engine bay.
The non return valve can be checked by operating the fuel pump so that pressure is built up aginst the closed tap of the fuel pressure gauge. The manual suggest that a drop of 0.5 bar after a certain time period indicates a fault.
It als implies that the fpr is the last thing to consider, but its easier to substitute if you have a known good one! The diaphram may have failed or as Dave as mentioned it could have an internal fault. If you suck on the vacuum port with a bit of pipe and get fuel in your mouth its dead! If you can feel it maintaining vacuum then at least the diaphram is intact.
So not being critical, but its less frustrating to test not guess and save all the head scratching. It could be one or more issues.

[diogocartier]

I am with the same issue!
but I have no ideas...

[UrS4boy]

I am with the same issue! but I have no ideas...

Re-read the above. Suggest you investigate/replace your fuel pressure regulator. If that doesn't work, it might be a bad fuel pump check valve. Click on the Fuel Pressure Regulator label (upper middle) in this diagram.

http://members.shaw.ca/speedtek/UrS%...ice%20Map.html (the other labels are live too)

[diogocartier]

Re-read the above. Suggest you investigate/replace your fuel pressure regulator. If that doesn't work, it might be a bad fuel pump check valve. Click on the Fuel Pressure Regulator label (upper middle) in this diagram.

http://members.shaw.ca/speedtek/UrS%...ice%20Map.html (the other labels are live too)

Yes, I'm believing that the issue is on FPR..
I'll try to replace it and see what happens..

[hermanio]

i replaced the FPR today with a new one and it didnt solve the problem. the injectors, FPR and check valve at the pump are things that i know are good. i begin to think that this problem has to do with original rs2 chipset. is this possible ? are there more rs2 owners with original chipset that have this problem ?

[hermanio]

i also wanted to rule out the original rs2 software, so i swapped it for a chipped one. but it didnt solve the problem. what i did notice is that when i try to start the car and it wont start right away, i hear a burble for the tank, maybe a vacuum in the tank ?

[hermanio]

just changed the injectors for an other orignal set i have, and now the car start without a problem. so it was a problem with the injectors. still cant get it, because the old ones were cleaned and tested.