Almost starts

[Sam83]

930 3.3L turbo

I was wondering if anyone could shed light as to why my car wont start.

When I turn the key it cranks, starts to start with a slight rumble, but does not as I keep cranking.

I can hear the fuel pump, smell gas, and hear the cdi whine.

It just will not stay started.

Any thoughts?

[Joe Bob]

CIS is about fuel pressure. Borrow or buy some gauges and a Bentley manual. Check start up fuel pressure.

[vintagecarlover]

Fuel fire and air. Takes all 3 and I'm in same boat as u with no start so will follow this. Might look at my thread for no start to see if u narrow it down.

[toddu]

GOOD fuel, fire and air. Lots of cars coming out of storage this time of year. My car sat for about 6 weeks and no dice. Had to drain the tank, rebuild the carbs. Runs fine now. Got lazy with the stabil.

Todd

[blpetry]

The symptoms youre describing sound like your frequency valve may not be functioning. On a NA car, one would simply remove the air filter and push up on the sensor plate with the key on and listen for the distinct buzz. Not sure you can easily get to the sensor plate on a 930, if not the next option is to install a jumper wire connecting pins 30, 87a and 87b on the lambda relay under the passenger seat and listen. If you need to do that I can get a pic showing what that looks like. Oh and make sure your dome light is working, as it powers the whole deal.

Disclaimer: im assuming the CIS on a 930 is similar enough that these NA procedures still apply. Someone please correct me if that's not the case.

[timmy2]

Try either grounding or lifting the white wire from the over boost switch, the sensor may be bad.
Send a PM to User name Kozmo, he's normally in the turbo forum, we went through a bunch of sensor/sender testing to get his car to run after he rebuilt it.

[prschmn]

From the description it's probably;y firing the cold start valve but then doesn't have enough fuel to stay running. High control pressure.low system pressure, or vacuum leaks may be the culprit. On most 930s there is an extension for mixture adjustment visible-barely, between the fuel distributor and air filter right above the trap door. rough indicator of low pressure is how much force to push it down with the ignition on. If you don't hear the nozzles squeaking when you do that your pressure isn't enough to run the car. Cold start will work with very little pressure so it will fire and stall. I'd start there and report your findings.

[Sam83]

Mark,

Is hi and low pressure caused by a faulty fuel pump?

Sorry, not sure how to do the test as suggested. I have an aftermarket
intercooler installed and can't see anything without taking it off. I will have to
remove it to test.

If the fuel pump is the problem then no need. Thanks for your reply!

[prschmn]

Well low pressure sure as hell is! Control and system pressure are two different things.
Bad pump and low system pressure-in your car approx 90 PSI rather than the 70 or
so SCs would use. Control pressure is what acts as your "choke" its low cold to allow the door to open further-richer and increases with temp to lean it out. Yours also has provision to richenit when under boost.
Maybe you can find a two year old that has tiny fingers to reach behind the intercooler?

[prschmn]

On another note-you might want to check that both pumps are running-check the fuse box for overheated terminals and cooked fuel pump wiring-not at all uncommon

[Sam83]

You state check that both pumps are running...

I only see one pump under the passenger back set area.
Where might the second pump be located.

Thanks again,

[prschmn]

Right behind the gas tank-like the mere NA peoples cars!

[Sam83]

Should the front fuel pump make a whining noise when the key is turned on?

[prschmn]

Fuel pumps always make some noise. More if there restricted,dry,or failing.
With both running they should sound the same-more like just a hum.

[gomezoneill]

One of the best threads on turbos.

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/547032-sticky-common-answers-why-my-car-doesnt-start.html

[Sam83]

Is removing the gas tank the easiest way to change the front fuel pump or is there a easier way?

[prschmn]

Remove it from under the car-if you're sure it's bad

[Sam83]

What's the best way to test a fuel pump for power? I have a test pin light and voltage meter but not sure how to connect either to test for power.

Is the fuel pump fuse #6 ?

Thanks

[prschmn]

sam, I think the best advice I could give you now is to get the car to someone
who has the right tools to test the system.Must be someone/place you know.

[Sam83]

I guess it was a stupid question I could figure out on my own..

There are a couple of Porsche dealers around here but... I'd rather not...


Thanks for all your help, suggestions, and replies!!!