Bradsters

All of a sudden, my fuel pump is not working on my 79. I have already replaced the fuse and relay. From the 928 Specialists site, I know that you can hear the fuel pump for a second after you release the ignition. I hear nothing now. I was wondering if I should also be able to hear the in-tank pump? If that pump was already dead, is the external pump sufficient without having to change the in-tank pump?

I would appreciate any thoughts.

Dennis Wilson

It depends on how long you crank. If the car doesn't start in a few seconds, the pump should shut off even though you are still cranking. Can you hear the pump when you turn the key to the on position (not crank)? Have you measured the fuel pump output? It should pump about 1.1 liters in 30 seconds. If you have an internal pump, it's doubtful that you could hear it.

Dennis

WallyP

Every 928 owner is required by international law to have a relay jumper in the glove box.

Get approximately two feet of two-conductor 18 gage stranded insulated electrical wire. Lamp cord or "zip" cord, sold to connect table lamps to the wall socket is perfect.
Get two 1/4" male flat spade connectors.
Get one single-throw, single-pole toggle switch.

On one end of the wire, put a male spade connector on each conductor.
On the other end, hook one conductor to each terminal of the toggle switch.

You now have a relay jumper that can be used as a testing tool or as an emergency "get home" relay jumper. This should alway be kept in the 928 glove box, not in the tool box at home!

On the '79, remove relay XVII, the fuel pump relay. Make sure that the toggle switch is off, and install the jumper between terminals 30 (+12 vdc) and 87 (load) in the relay socket.

Turn the toggle switch on. You should be able to hear the fuel pumps buzz. Remember that the pumps will get power regardless of ignition switch position or engine condition as long as the jumper switch is on.

If no pumps are running, the most probable cause is a bad fuse or fuse connection on fuse #22.

If you can't tell whether one or two pumps are
running, remove the fuel pump cover and unplug the pumps one at a time to see if both run.

The outside pump will not be sufficient if the inside pump is dead.

Curt

Im somewhat confused on this two fuel pump thing. A few months ago I pulled down the fuel tank fuel pump that was located under the tank. The fuel pump was not inside the tank but located under the tank with a metal shield to cover it from debris. Is this the pump that everyone is talking about being inside the tank?? And where would the second one be? I removed the tank because the top breather had been crushed shut and I was not able to fill the tank to full. It would only allow me to fill it just over half a tank. I cleaned the tank and fuel lines and fixed the breather line and reinstalled. No problems with filling her up since then.

Jim Wilson

Curt,

AFAIK many cars do not have an in-tank fuel pump, the pump you saw was the main (and only) pump. An in-tank pump will require wires coming out of the tank I believe.

Jim Wilson
'79 Euro 5-speed

WallyP

Standard fuel pump location on virtually all 928s is under the cover between the tank and rear bumper cover. Some cars - very early cars, Japanese and Aussie cars, very late cars, etc. - had two pumps. The second pump is installed on the end of the fuel line inside the tank.

With possible changes by P.O.'s, the only way to know what you have is to look. You can pull the cover and check the electrical wiring for a first check.

Bradsters

Thanks everyone. I do have wires going to the fuel tank drain. Therefore, I suppose that I have two pumps. As luck would have it, following Mr. Plumley's advice in other posts, I cleaned the the fuse contacts and it started right up. My question was premature this time, but I am sure that the fuel pump[s] will be the next thing to go.

Again, Thanks.