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1980 VW rabbit, manual/fuel injection: I am original owner. Problem started few years ago & has been getting worse. Apx 110,000 miles. Starts & runs OK when cold. Starts & runs OK when warm. Idles & runs fine, like new. Gas mileage getting worse. No noticeable leaks or smells. compression is OK. No oil loss or oil burning. When engine is warm and left off for anywhere between 20-minutes or so and 4 hours or so, it is very difficult to restart. It will catch briefly, then stall, and then refuse to start without huge amounts of cranking (with rest periods). I checked entire ignition system, everything seems fine. Replaced points, plugs, plug wires, rotor, cap. Cleaned coil towers. Reset dwell & timing -- no change. I tried installing a jumper switch
& test light to run the fuel pump when engine is off and monitor pump
when engine is on. Pump runs properly when engine is on or cranking.
If I run the fuel pump for apx 30 seconds (with the bypass switch) when the engine is hard to start -- then it will start but run poorly for apx 10 seconds and then run OK.
I am suspecting either the accumulator or the fuel pump check valve but I don't understand why it starts & runs OK when cold. Am I on the right track? What to do??
It starts from cold because the auto choke is on ,allowing a richer mixture ,try removing the sender unit in the tank and seeing if the connection from the pump to the outlet connection is ok or leaking causing a loss of fuel pressure
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More info is needed. Has it been upgraded to fuel injection? What is idle set to in park? Is there an aftermarket cam installed?
If it was originally in a manual transmission car and your car is automatic the idle will need to be adjusted higher. If it has been upgraded to fuel injection (throttle body injection) I would start by checking the idle air control.
If we have more info about the engine we can help out more.
Ther are a few items that could be causing your problem. first there is a temp sensor that turns on a cold start valve to give it a shot of fuel to help start when cold. second of corse would be the cold start valve is bad, and not spraying like it should. And then you also have an item called an auxillary air valve that lets in more air durring start up that could be bad. and ect ect ect. The best thing to do would be to get a book called Bosh Fuel Injection & Engine Managment written by Charles Probst and published by Robert Bently. i got mine at Books a Million, but am sure you could order one on Ammazon. You have what is called a continuios fuel injection system CSI for short, and can be a bit of a bear to work on without any books. Once you read and understand what you have , the better of you will be. On the bright note, this is one of the most reliable type of injection systems on the market, and yours being an early year without any type of computer, is very easy to work on.
you need to check the accumulator and make sure you are getting the correct fuel line psi. Also if it sat a long time with old gas in it it could just be old gas accumulation and deposits. get a good fuel line and injector cleaner one that dosn't say STP and cost's more than $15. One that has to be done threw the fuel line or injector ram. You can try using seafoam, its seams to work pretty good in this type of situation just look it up on UTube.
It sounds like it could be a problem with the fuel pressure regulator. When the engine is cold, there is a cold start valve that dumps extra fuel to start a cold engine.
Not showing where, but follow the tubes and you should find everything.
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