Kneale Brownson

Check with Chris Semple Force 5 Automotive

eventoday

Hi again
So I am still struggling with the hot no start issue. I feel like is is actually getting worse too.
This is probably a silly thought but could there be any correlation to me putting a new cd player head unit in. The issue started after I did that. Now to be fair I only owned the car a week and half before that so ...

The only thing I know for sure right now is car will start if pedal is held down or you pick the plate up under the fuel distributor. (mechanic told me about the plate)

My mechanic is going to check for small vacuum leaks when I take it back to him Monday.

We haven't tried speed sensor, hall sensor or fuel relay yet. These were all suggestions but with limited funds don't know which one to try first. I am going to have to start somewhere I suppose. What do you think the best place to start is?

audiqv8

not starting after the engine is shut off then I would start with the crank sensor. BTW raise the hood to allow for the hot air to escape and it should start after the engine has cooled down. Also if you haven't check the heater control valve yet, check to see if it is about to crack. This has nothing to do with your hot start problem, but you don't want to ruin the engine because the heater control valve fail and you lost all coolant to the engine.

audi_marv

FUEL PRESSURE REGULATOR.

Kneale Brownson

issues with the fuel pressure regulator on the top of the fuel pump usually result in cold start issues, not hot restarts.

audi_marv

Last time I had a no start issue where I had to lift up the air plate to start the vehicle, it turned out to be the fuel pressure regulator. I have the needle type regulator though, but when the car was hot, it would not hold pressure in the lines. The car would need to crank forever to build up the pressure, then it would start (or I could lift the plate). I guess when the car was hot, the O-rings would not hold the pressure. When the car was cold, it was ok (maybe due to the cold start valve helping out).

A simple pressure check would confirm this, but it cured my hot no starts.
Could also be a bad Throttle Sensor...if the only car starts with the pedal to the floor. Just my 2 cents worth....

eventoday

Thanks Audimarv.

Is the fuel pressure regulator the same as the control pressure regulator?
My mechanic mentioned to that to me today.

Jake

audi_marv

Not sure what manual your mechanic may be using/looking at....but I think he may be referring to the Warm Up Control Valve.

Best bet is for him, and you, to become very familiar with the sjmautotechnik.com site !!

eventoday

Yeah Ive been all over that site.
Its really good. He tested the pressure in the fuel regulator today and it was good so he has some other things he is going to try today too. Not sure what.

audi_marv

Well from there, he could go to the fuel accumulator, to the fuel pump check valve, and the fuel injectors themselves....to see if they are all holding fuel pressure after shutoff.

And to simply rule out the crank and ignition sensors, he can swap them, as they are interchangeable, and note the result.