911 hard to start when warm

micky_ray · 03-03-2004, 10:53 AM

I recently replaced the cylinder head temp sensor on my 85 911, along with an ignition system tune up (wires and all). The car now starts and runs much better when it is cold, however once the engine has warmed up it doesn't want to start! It will eventually start after cranking it for a while, but it used to start fine all the time. Also the car doesn't seem to have the zip that it used to have.

Are there any adjustments that can be made to correct this? I was under the impression that a DME controlled engine didn't offer a lot in the way of adjustment. Or should I be looking at other sensors that may also have gone bad (airflow, etc.)?

I don't know if it matters, but this car sat undriven for almost ten years until I rescued it a couple years ago. It was stored unprepared with fuel and oil sitting in it.

Thanks,
Micky

bigchillcar · bigchillcar's Garage

couple checks:
fuel pump check valve could have failed...not holding residual pressure after warm shutdown...or fuel accumulator.

lambda (oxygen sensor) gone bad...
ryan

RickM · RickM's Garage

The Fuel accumulator is a very common cause of warm start issues on a CIS car but does a Motronic car have a Fuel Accumulator?

micky_ray · 03-03-2004, 11:38 AM

Forgot to mention, this is a grey market car. No O2 sensor, and a mock cat.

DavidI · 03-03-2004, 11:45 AM

In my 83SC I had a similar problem. I researched info on this board and narrowed the problem as a bad fuel accumulator. I changed the part and solved the problem. Do a search on this board. There are a lot of threads regarding this type of problem.

Good luck, David

nhromyak · nhromyak's Garage

1) fuel accumulator

2) Check the intake gaskets too. These tend to come loose (loctite? j/k).
These gaskets are also known to become brittle and leak.

3) check the grounds on the #1 intake runner too!

Good luck.

RickM · RickM's Garage

I do not believe an '85 Carrera has a Fuel Accumulator. It is not a CIS controlled SC.

nhromyak · nhromyak's Garage

Oops, your right.

No accumulator.

dan911 · 03-03-2004, 05:06 PM

Hmmm, I am having the same warm-start problem on and off. I was doing some researching and think it is most likely the fuel system. either the fuel pressure check valve or pump.

As for the zippiness part, could be the air flow meter or the fuel injection pressure regulator.

Keep us informed abt how it goes.