Originally Posted by Stevestik

CHECK YOUR GROUNDS.

Originally Posted by James Bailey

Four out of six times when a 928 has stopped running while I was driving it has been a RELAY....one time timing belt let go and one time the engine ate an extra bolt and split the cylinder destroyed the block.... Also had a control press reg (warm up) on a CIS car go way bad but the car still would move ...just barely. Then there was the 2/6 rod bearings at Willow (still ran), the broken lower ball joint , broken shift rod , loose cv joint , broken 5 th gear , ....

Originally Posted by gbarron

<<...>>
Keep in mind the pump will cut out at the max system pressure so if you are trying to listen for a noise and don't hear anything it could be that the fuel system is up to pressure already....which may mean the problem lies elsewhere. Do all your basic checks first (power, connections, etc.)

Glenn

Originally Posted by WallyP

While this is not a criticism of anyone on the Forum - just because a faulty fuel pump caused a problem on someone else's car does NOT mean that the fuel pump is your problem. It will be very, very expensive if you start trying to replace everything that has caused a problem for someone else. Listen to the ideas that folks offer, but do some testing and checking to try to determine what YOUR problem is.

If/when the car dies again, kneel by the rear bumper and listen for the fuel pump whine or buzz as someone operates the starter. If you hear a buzz, the pump is not too likely to be your problem.

If/when the car dies again, quickly look at the gauges and warning lights as the engine stops. If the red lights come on while the engine is turning, but go off when it stops, suspect the ignition switch. If the temp and fuel gauges stay at their normal position before you touch the ignition switch (this is as the dies and just stops turning), the ignition switch MAY be OK.

If the tach drops to zero BEFORE the engine stops turning as it dies, the crank sensor or a faulty connection may be the problem.

If you learn how the systems work, you have a much better chance of quickly determining why the engine is dying.

Your choices include:
- Shotgun approach - replace anything that anyone suggests. Expensive, doesn't work well.
- Give the car to an honest, knowledgeable tech and pay him to troubleshoot. These folks are pretty rare, and they aren't cheap.
- Give the car to a random "Porsche expert" (which usually means 911 expert, not 928 expert) and pay him to learn about 928 problems. VERY expensive, rarely a happy outcome.
- Spend some serious time learning how to troubleshoot 928 problems. Time-consuming, expensive at first, may lead to repeated tows. Best method for most folks in the long run.

Let us know if we can help.

Originally Posted by dr bob

Glenn- this is not correct. The pump continues to run while the engine is running regardless of outlet pressure. The fuel pressure regulator (FPR) bleeds fuel back to the tank to correct for pressure variations regardless of flow through the injectors. The intake manifold pressure biases the fuel pressure, so that there is constant pressure drop across the injector nozzle and valve at differing engine loads.

Originally Posted by lrpman

Find someone with an Autoxray OBDII with the software. They can check it out and take a couple of rounds out of the shotgun for you.

Originally Posted by James Bailey

I do not think so ! the 928 LH did not get "memory" until 1990 as I recall...Also all 928s the fuel pump shuts of if the engine stops Like you crashed into a tree and catch on fire the fuel pump will stop because the engine is NOT running. Some 928s have been jumpered so the pump runs when the ignition is on to "fix" early stages of LH failure but is a bad idea.

Originally Posted by Landseer

On the 84, the fuel pump runs when key reaches the on position.
If you don't go further and start the car, or if there is a massive air leak, the AFM barn door does not open. If it does not open, the fuel pump shuts down within a couple seconds.