Jersey_Sam

83 manual US spec.

car was running fine. Now when i turn the key, i dont hear the 2 seconds buzz from the fuel pump. Ran direct 12v to fuel pump in the back and it ran fine. So the pump is working.

The fuse is fine as well, having 12 volts to the fuse.
Key On/Off, Jumpered 30 and 87 no go.

I pulled the relay and tried the relay on Jay's 928 and it ran fine. So the relay is good.

with the key on, i get 12 volts to pin 15 on the relay. so I then jumpered 15 to 87 and the pump buzzed so i cranked and it fired up. I drove it around the block and it ran like a champ. I just dont wanna keep it jumpered from 15 to 87. I need to get 12v back on to 30.

I researched and read that the 30 pin should get direct 12v from battery post in rear of car. however, im getting no voltage.

I have the green wire, so i do not have a Crank Position Sensor (unless im mistaken - i have a brand new CPS in the basement from my previous 928).

grounds are clean and shiny.

Should i drop the panel and check the back wires that feed into the relay pins? so if the wire going into pin30 is corroded or loose? Or is there something else i need to check first? Also i read that the pump has a ground in the RR quarter of the rear latch/trunk.

Thanks again.

Sam

G.P.

I'm no expert but a quick check of the 83 wiring diagram says that fuse 22 feeds terminal 30 on the fuel pump relay, I assume that this is the fuse you checked. The ground in the RR quarter should be OK because you were able to run the pump/car with 12V jumpered from terminals 15 to 87.
If the above is correct and after checking that you have 12V on the battery side of fuse 22, I would pull the panel and check the connections on the back.
Hope this helps.
I'm bored at work.

Jersey_Sam

LOL thats funny. ive been getting bored at work lately!

yes fuse 13 was checked and works fine.

thanks.

Jersey_Sam

LOL thats funny. ive been getting bored at work lately!

yes fuse 13 was checked and works fine.

thanks.

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

dr bob

Look at Fuse 22. As much as I trust most third-part docs, I REALLY trust the WSM diagrams more. The diagram shows fuse 22 feeding the fuel pump relay 30 pin. 16 Amp fuse. It may just need the tabs cleaned, easy to determine with a DVM reading voltage on both ends of the fuse. That cleaning is part of the annual electrical maintenance protocol.

The wiring diagrams show that fuse 22 receives battery power from a 30 bus in the CE panel. Later cars have a dedicated power feed from the battery for the pump relay. Look at the battery and see if there are accessory red wires connected at the positive post. Disassemble, clean until shiny, reassemble. The diagram may show the function, but be missing a connection detail. You'll want to look yourself.

j.kenzie@sbcglobal.net

Like Dr. Bob said. You may even want to pull the CE panel and visually inspect the grey wire going from Fuse 22 to the 30 terminal on the relay socket. More than likely, somewhere between the fuse holder connections and the relay socket, you have some corrosion or other problem.
Good luck,
Dave

Jersey_Sam

will do Dr. Bob, thank you. Will report back my findings, because i know others can benefit from this thread.

Sam

Jersey_Sam

Ok will do. thanks Dave. Will report back.

Jersey_Sam

Gents you were right. Even though the fuse chart said "not used", fuse 22 was broken.
So I replaced it and now the pump buzzes at the turn of the key and it fired up with the FP relay back in place.

Schnellpanzer is happy and so am I.

thank you gents.

Sam

G.P.

Excellent
I've had my 87 for three years, and have found that I need to double check that what I am understanding from the wiring diagrams, is what I am finding on the car.

dzaprev

I think you were jumping wrong wires if I remember right . But with no power wouldn't make a difference