I really need some help here w/ my 911, she has really let me down as of late, some of the time, she will start right up but then 5 minutes later nothing but turn ans turn. I have checked the fuel pump, that seems fine, I have replaced the cap, button and plugs, no effect, could the distributer be going bad? would one of those electronic ignition systems help? can the Perna-tune box be going out intermittnetely? any help would be greatly appreciated as I am unable to really drive the car as I cannot trust it to get me home once I get it out. love the car but am forced to take my non-Porsche at this time. Any good repair shops within the Charleston WV, Lexington KY, Cincinnatti OH area that anyone has had dealing with.

thanks,
Chris (very frustrated!!)

 

Does it matter if the engine is hot or cold?

When the problem happens does it seem like it turn over strongly but there is just no spark? - if so, might be the CD box...

 

At the risk of being ironic, it is either gas or spark. I suggest you check for a spark at the coil wire, and if present, at a plug wire end, obviously when it is misbehaving and won't start. It could also be gas. If the accumulator or check valve is bad, it can take some seconds of cranking for the pressure to come up. Also check that the air flow plate is free to move and not sticking in the closed position.
You can also test the fuel flow by turning the ignition to "on", and lifting the air flow plate. you should hear the fuel pump start and the fuel squealing through the injectors. Don;t do this for too long or you will fill the engine with fuel.

Once you identify which system it is that is causing the problem, We can help from there.

 

I have a 77S and I had a similar problem . Turns out the points (bosch) were failing . So replace your points first , its simple and cheap .

Jim

 

All right, thanks to all you gave me some suggestions, I did the fuel/air plate test, the fuel pump is running fine, the injectors could be clogged but it sure smells like it is pumping plenty of fuel. I checked the points they are fine, no effect. I am starting to feel that it is probably electrical in nature, if I try to start her for a few seconds she will grind and grind and then I ture the key off, if I turn the key quickly to on you can hear her sort of "burp", she just lets out a little puff or small backfire, I have replaced the coil w/ a new one to no effect, can it be she is not getting enough fuel or is the CDI (Permatune) box going out. this problems happens both when the motor is cold and when it is hot.
thanks in advance.
Chris