I can't get my 1983 928 to start, the spark plugs are firing but there doesn't seem to be fuel. There is no pressure at the fuel rails. I checked the electrical connections, in the hatch opening for the gas tank, for voltage with the ignition on. One terminal has battery voltage, the second terminal shows @ 3.8 volts, an the third terminal appears to be ground. I am assuming that the fuel pump is in the tank because and that it is not pumping because I can't hear it.
If I am looking in the wrong place for the pump or if I am overlooking something in diagnosing this problem please let me know.
Thanks

 

fuel pump relay

 

Nope, fuel pump for an 83 is under a small panel under the fuel tank on the passenger side. If remember correctly, it is 2 10MM nuts that hold it on. But, I would jumper the fuel pump relay before I tried anything else.

 

Damn Mark, you beat me to it!

 

If you have 2 fuel pumps (some cars did and most do not, I'm not sure the MY of the cars with 2) one will be in the tank and the other just outside of the tank in the same area (access hatch at the passenger side rear of the car) as the fuel filter. If you just have one it is beside the fuel filter external to the tank.

The fuel pumps do not engage and pressure the fuel lines unless you are cranking the engine - or have the fuel pump jumpered as suggested above.

 

Where is the fuel pump relay?
Thanks
Jorge

 

It's on the main fuse panel in the passenger footwell. Follow this link. It's relay XVII.

https://www.928gt.com/t-8384fuse.aspx

To jumper it, make a jumper out of a piece of wire (16 ga.) and you want to jumper pins 30 and 87. You can see which pins these are by looking at the relay itself. The fuel pump will always be on now, so don't leave it there when the car if off for too long or you'll burn up the pump and kill your battery.

Edit: Removed bad information... thought you could swap horn relay on 83, but you cannot according to Mr. Fabio.

 

On an 83 the horn and fuel pump relay are not the same. Thats on an S-4. The fuel pump relay on the 83-84 is the only one like it in the panel. You will have to jump the terminals to test and then order another. Here is a link to the relay you may need. https://www.928gt.com/p-1176-relay--...78-84-oem.aspx

 

Don't leave the jumper in place as the fuel pump will continue to run even if the engine is not running.

 

I tried the jumper and could hear the fuel pump run but was not able to get the engine to run for more than a few seconds. I tried to get it to run even if it was for a few seconds but could not get it to do it again. The tank has maybe 2 gallons of gas could this be a problem or is there something else preventing the car from running?
Thanks
Jorge
PS: Thanks to all for your helpful posts.

 

Yes. make sure you have at least 5 gallons in it. Let us know what you find out.

 

Jack,
The PO told me that the gas tank has a leak and that is why it didn't have any gas when I bought it and why I only put 2 gallons in it. What is the reason for 5 gallons?

Thanks
Jorge

 

The reason is to be able to eliminate lack of fuel in the tank being your problem.

 

It is alive! For the first time in 6 years it is running!
The fuel pump relay was bad (Mark) and there wasn't enough gas in the tank(Jack).
Thanks to all for your help with diagnosing this problem and the useful links.
Jorge

 

Good deal. Nice to know there is now another shark swimming around. Thanks for letting us know.