Car won't start: seems like fuel rail is clogged

[ninsei]

Hi. I'm troubleshooting a problem with my 2000 C2 Tip. starter cranks but engine doesn't turn over. I remove the fuel input hose from the driver's side engine bay fuel rail and when I run the fuel pump (by jumpering the relay) a nice amount of fuel comes out. Put that hose back and remove the fuel rail return line, run the pump, not a drop. So fuel is getting to the fuel rail but not passing thru it/coming back out. I can't believe a foreign particle could've gotten in there cause this is past the fuel filter. I was thinking about spraying compressed air in there, but that's shooting in the dark. Any help is appreciated. Removing the fuel rail seems pretty daunting....

[ninsei]

Ah, if I remove the fuel pressure regulator, and run the fuel pump, fuel does come out of the hole that the fuel pressure reg was sitting in. Maybe the fuel pressure regulator is bad cause it seems like it's a kind of valve that sits in the path. I would like to T-shoot that part to verify. I have a hand vacuum pump and I can give it vacuum but when I do I don't see or hear anything special.

[ninsei]

ordered a new fuel pressure regulator. I'll report back in a few days when it arrives.

[ninsei]

replaced the fuel pressure regulator and it still won't start. I'll check the fuel return line tomorrow but now I have this theory:

the fuel has failed in such a way that it still pumps fuel when there's no resistance, but cannot produce pressure in a closed system.

The evidence was that it doesn't have enough pressure to pass thru the fuel regulator. Maybe I'll pick up a fuel pressure kit from Sears tomorrow. But could that be it?

[Loren]

How many different threads have you started - 3?

Please tell us the exact problem and any fault codes and we will try to help.

[ninsei]

High level view of the problem is that the car cranks but doesn't start. No fault codes in Durametric. Fuel pump pumps fuel but I have not checked pressure yet. Any help is appreciated as I'm pretty desperate at this point.

[ninsei]

If I run the fuel pump for a few seconds and remove the fuel return line from the fuel rail: not a drop comes out. I don't have a pressure tester but it would have to have read zero if I connected it there. My current theory is that the fuel pump runs but doesn't really produce enough pressure. I guess I'll order the $300.00 fuel pump and see how it goes.

[whall]

Before you purchase a new fuel pump, check the proper functioning of the crankshaft position sensor. A bad one may not throw any codes but will keep the fuel pump from operating when you try to start the engine.

Here's a link that may be of interest:

http://www.ppbb.com/phorum/search.php?0,search=crankshaft+position,author=,page=1,match_type=ALL,match_dates=0,match_forum=ALL,match_threads=0

Bill

Edited August 20, 2010 by whall

[ninsei]

Thx. Doesn't seem to easy to chk that. But I did check one thing: If I remove the fuel pump relay, put a voltmeter on pins 85/86, and turn the key, I do get constant 12 volts. Which I guess means the DME is trying to start the engine (run the fuel pump).

[tholyoak]

If the pressure regulator has failed and isn't allowing return it will result in too high of pressure in the rail. If this is true, the high pressure in the rail can result in the injectors drawing excessive current and the DME will not fire any of the injectors. To test for this, disconnect one injector and try and start the car. Disconnecting one injector will reduce the current enough for the DME to fire the injectors. The car wil run rough but it will run. If this happens then your FPR is bad. If it doesn't help you can look elsewhere.

This procedure worked on the older Porsches with DME injection so I think it should work with the newer system as well.

-Todd

[ninsei]

cool idea. thx very much. i tried and same result though. i doubt the fuel pressure regulator is bad since I just replaced it during this T-shoot cause I though it was stuck closed.

[ninsei]

still troubleshooting this. I was wondering of the fuel sender (AKA fuel level sender, above the fuel pump) could cause this. Is that thing just a passthru or are there actually valves in there that have been known to fail?

[Dharn55]

Per Whail, check the crank position sensor. This is what happened to me once. Car cranked fine but would not start. spent some time chasing the fuel pressure which I thought was the problem. Same basic symptoms you have. then I was told to check the crank position sensor. Put my Durametric on it and it showed no signal from the crank position sensor. The fuel system needs a signal from the sensor or it shuts off. So you get some initial fuel flow when the ignition is turned on, then it shuts down when there is no signal from the sensor. Easy to check for the signal with the Durametric of the Porsche OEM tool.

I replaced mine, which is a story of its own as it was corroded in place, had to drop the engine, separate the trans and beat the thing out in pieces (wonderful Chicago winters and salt on the roads). Normally this is an easy replacement . Once replaced the car started and ran fine.

Edited August 28, 2010 by Dharn55

[ninsei]

Thx everyone for the ideas. This was the problem: when I removed the fuel sender to replace the fuel pump, I saw that the two hoses (from fuel pump to sender) where disconnected from the fuel sender. They were sort of on but not clicked in and very loose. That would cause all the symptoms I've been having. I replaced the fuel pump anyway and made sure the hoses clicked in. car started right up.

BTW: I had to make a special tool (equivalent to VW 3217 or whatever) to remove the plastic fuel sender retaining ring. I don't know how the heck you folks get it off without that tool. Banging it on the edges didn't work for me.