Porsche Enthusiasts Club Forum

I broke down last week in the middle of a normal spirited evening drive. I just lost all power. While I waited for a tow home, I tried a spare DME relay, checked all the fuses, and replugged connections to the crank sensors, AFM, and injectors. But still no go.

I have since tested both crank sensors. I replaced one last year, so as I was a bit confused by the test results, I replaced the other just to be sure. They both test with good resistance, and the tach bounces when cranking. I swapped the sensor plugs just in case I had mixed those up in the confusion, but the tach didn't bounce when they were swapped. All the sensor leads are in good condition. So AFAIK this rules out any sensor wiring issues.

Today I made a DME relay jumper lead according to Clarks.
The strange thing with this, was that although everything clicked on with the jumper lead connected, the starter motor would not engage on the key. I put the relay back in, and the starter motor worked again (but still the engine won't fire). With the jumper lead in, I could not hear the fuel pump running, even with my head right next to it at the back of the car.

I also tried to start it with only 2 or 3 injectors connected, as this can diagnose a faulty Fuel Pressure Regulator if it starts on 2 or 3 injectors.

So with what I know about my problems and 944's, I am down to either a faulty fuel pump or ECU. Any further suggestions?

I have seen the connection to the fuel pump corroded before there is a connector by the fuel pump near the filter

While you are at that connector it might be worth checking you have voltage at the fuel pump with the ignition on, if you have its probably the pump, if not i would try swapping your ecu for a known good one, and it might be worth buying a new dme relay just to be sure. a spare is always handy.
its just eliminating things one at a time.