GRTeese

Hi,

Vroomhilda, my '80 Euro "S" 5-speed, has been down about one month now. Engine died (fuel stopped flowing) on the freeway, flatbed home. I've replaced the fuel pump relay (fuel pump itself works), ignition coil, green wire, and Ignition Control Unit. The fuel pump still won't go on when I turn the key. Any Ideas? The last thing I want to do is take her to the Porsche shop in Charlotte as they aren't very familiar with the 928, but it is starting to look that way.

ErnestSw

Wouldn't be the first time a new relay was bad out of the box.

Lizard928

ign switch? also check for signals at the different terminals which engage the relay,

also when you jumper the relay does the car run?

GRTeese

All the terminals for the pump relay read properly. The engine won't start even with the relay jumped. I just pulled a couple of fuel lines - no fuel flowing. The pump makes noise as if it is working. On to the fuel filter...

Lizard928

you have of course made sure there is gas in the tank *blocks waiting for smack*

GRTeese

Without a doubt. Almost a full tank. There is fuel in the fuel return line.
more to come...

Lizard928

ok I would be removing the connector at the output of the fuel filter and then having someone bridge the connector and making sure you have good flow out of there, if you do follow the line and make sure something didnt get kicked up and under the car pinching a line, if no find the other end of this hose and verify there is fuel coming out of here,

is there anyway for a fuel pressure regulator to fail and stop fuel flow?

jpitman2

Do flow test at engine bay - 1/2 gal/min comes to mind.
jp 83 S

ViribusUnits

Get a timeing light, or a spart tester, and make sure the ignition system is doing it's thing.

It's possible it's not.

Dennis Wilson

As JP mentioned, you should test the pump output. It should flow 1,100 ML in 30 seconds. Test it at the pump outlet, then again at the inlet to the fuel distributor. If low at the pump, the pump is bad or there is a restriction on the screen in the tank. If the output is OK at the pump but low at the distributor, look for a restriction in the line or a plugged fuel filter.

Dennis

Garth S

Are there not two (2) fuel pumps on the CIS cars, the first of which is in the tank and the second external with the filter? If so.....

Dennis Wilson

Garth,

Some have two pumps and some don't. Neither of my CIS 928's have two pumps. The only way to tell for sure is to see if the tank outlet has electrical connectors. One pump or two, there is still a screen in the tank that can plug up and restrict flow.

Dennis

Garth S

Dennis,
The screen is a good call, as is anything that can inhibit flow. My comment on the second pump issue was for the (unlikely) possibility of an oversight: - "what?.. where do those wires go? holy crap!...."

Dennis Wilson

Garth,

Somewhere I have read that the early 928's that were destined for hot climates had two pumps and all others had one. Up-Fixin? When you get my age, the senior moments are almost constant. My 931 came with two pumps (both bad) which I replaced with a 928 intank screen and a 6.5 bar Pierberg external pump. So far no problems with the 1 bar boost or during stop and go traffic when the temps was 110 F.

My 78 euro had sat for 10+ years. Everything in the fuel system had a 1/16" (minimum) coating of lacquer buildup. A double helping of Techron just loosened the lacquer and caused further blockages. Everything except the WUR had to be replaced or rebuilt.

Dennis

Chucker

What about the fuel check valve? I have an extra one if needed to test the situation.