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A2 GTI fuelsystem woes -- Distributor, Cold Start Valve?

Hello folks,

I have an '85 GTI with an '87 16v engine that won't start. It sat for a year or more and had the old gas pumped through the system, although now I've drained it and replaced it with clean gas + fuel system cleaner.

While the problem really could be anything, there are two questions I'm working on at this point and would appreciate any insights.

1 - When cranking, I get fuel going through the line to the cold start valve but am not seeing any output from the valve itself. I couldn't get any flow while running the CSV test in the Bentley, and it seems that the coolant temp sensor is functioning. I've soaked the CSV input/ output in Seafoam cleaner... is there any way to force the valve open to verify whether it is indeed clogged?

2 - The fuel distributor is only sending gas to the CSV -- I'm not getting any flow out of the other four injector outlets on the distributor body. I've tried cranking with the air flow sensor in various positions, but I still only get flow to the CSV port. Should there be flow to the others?

Thanks so much for any help. I suspect that there may be some vacuum and electrical gremlins... the car was sitting in an rat-prone area. I'd love to just narrow this down piece by piece.

All best, Nathan

Reply to
Nathan
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"Nathan" schreef in bericht news: snipped-for-privacy@i13g2000prf.googlegroups.com...

The cold start valve is controlled by a thermo time switch. This means it's getting only power for a certain time (seconds) and if the coolant temperature is below a certain threshold. Do you have +12V a couple of seconds at the valve while cranking?

SFC

Reply to
SFC

berichtnews: snipped-for-privacy@i13g2000prf.googlegroups.com...

Nope.. I'm seeing zero volts at the cold start valve harness. Continuity seems fine between the thermo time switch harness and the csv, and the coolant is probably about 55 degrees F, so I suppose that means the switch is busted (or the ground is bad?). Any suggestions for jumpering the switch to verify the operation of the valve? If I'll be placing an order, might as well catch all I can this go round...

Also, any insights regarding the behavior of the fuel distributor? While cranking, it's only routing fuel to the cold start valve and not to any of the four injectors.

Thanks again for the help, Nathan

Reply to
Nathan

The tts switches the csv to ground. So one terminal (black wire) of the csv connector should have +12v while cranking. What I always used to do was to remove the fuel pump relay and put a jumper wtih a switch between the power terminals (30-87). This will run the pump continiously making trouble shooting a lot easier. To see if the injectors are working/getting fuel remove the boot on the f.distrbutor and lift the big disc a bit. With the pump running this will be hard so before you hit the pump wedge something between the disc so it'll stay lifted. Place the injectors in a container. There will be a zooming sound when they crack open. If nothing happens you can try to lift the disk a bit more.

SFC

Reply to
SFC

Thanks for the tips. Running the pump continuously with the jumper, I'm still seeing the same behavior -- fuel is only delivered to the cold start valve port on the fuel distributor. Changing the position of the air flow plate doesn't have an effect.

Any thoughts on where else to look? All the electrical tests on the 25- pin control module check out, although I don't have a harness to run the Bentley tests on the differential pressure regulator. If it's getting a bad signal, would that create the condition I'm seeing in which no fuel is being sent to the injectors?

Thanks again, Nathan

Reply to
Nathan

ign has to be on while doing the test the Fuel Pressure Regulator, if electronic, has to have current going to it along with ground and the FPR still could be bad. I have sometimes found broken ground wires. So yes it has to have power & ground along with being good for the injectors to get the proper fuel coming out. There should be a relay that powers up some of the FI components too. I keep a spare FPR or two for testing purposes that I have pulled off of cars at the junk yard. ;-) AND at the J-Yard I have cut a couple of 2 prong plugs so I could hook a digital volt ohm meter to the FPR.

There was someone just searching for a running/stalling problem with his VW. He found out that there was no fuel in the tank. 8-)

Reply to
dave AKA vwdoc1

Hi Dave, Thanks a bunch for the ideas. I'll definitely go after some two-prong harnesses at the junk yard today and will try a second FPR I have lying around.

Do you know where the FPR's ground is? I've been repairing some wire damage from rats as I go, and I'd love to hunt down a broken ground that brings this thing back to life!

Also, thanks for the heads up on checking the simple things first -- there is indeed clean gas in the tank, good flow/pressure at the fuel distributor, good spark... but only fuel going to the non-functioning cold start valve!

Thanks again, Nathan

Reply to
Nathan

Some success! It seems that the slapping on the new pressure regulator has brought fuel to the injector ports. I tightened down the injector lines and cranked away.. got a bit of lumpy cough, but we're not out of the woods just yet. I'll try to find a cold start valve and thermo time switch at the junk yard and see where that gets me.

Also, as I cranked, I started to hear a hiss and found fuel splattering around down by the main pump/filter. I can't imagine that I'll get very far with with a leak like that -- might be a good time to replace the filter since the car's been sitting for a long time with bad gas.

Should I replace the pump as well? How about the accumulator or any other components down there?

Thanks again, Nathan

Reply to
Nathan

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