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'92 944T no power to fuel pump after not being used for 4 months.

deadken

Member
Joined
Mar 31, 2009
Location
Long Island, NY
I parked my Blue 1992 944T (yeah, I've had several) earlier this year since the AC doesn't work and I wanted to use other cars for the hot weather months. Well, this global pandemic thing has kept me busier than I expected and I didn't get around to starting moving it every now and again like I usually do to keep the brakes, exhaust, etc.. in good working order.

A few weeks ago, I went to start it and of course the battery was dead. I put my jumper pack on it and it wouldn't start. I noticed that I didn't hear the fuel pump working. I left it for another week or so until I replaced the battery (that one was rather old) and of course, it still wouldn't start. So, I grabbed the fuel pump relay from my old Green 944T and swapped that it hoping it would solve the problem, it didn't.

So, I went to the trunk and took out the mat and access panel to get at the fuel pump. I had my son turn the key on and off a few times while I checked for voltage (no voltage). Then I realized that I think that I should be checking the pump under the car (and not the 'pre' pump). So, I figured that I'd check in here in case anyone is familiar with this and wants to guide me in diagnosing this.

EDIT: At this point, I am heading out to check fuse #1 which should have power with the key on. Then, it goes through on the brown wire to feed the fuel pump relay, which comes out on a pink wire and feeds the primary fuel pump and continues on to feed fuse #11, which feeds the prime pump and the O2 sensor heating element.

BTW: What is the best source for wiring diagrams for our old Volvo's? It's time I made a worthwhile investment! I've been using THESE
 
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Okay, here's a well learned lesson.... Be sure that you grab the right white rectangular relay when you swap in a spare relay to test a simple problem!

As it ends up, I just took apart half the dash (center console, kick panels, MCC, etc...) just to find out that I had swapped the overdrive relay, not the fuel pump relay :-(

I'm going to put things back together and drive my car!

Oh, and I found these WIRING DIAGRAMS for a 1993 944 which I think are a lot nicer to use. Just remember to verify your circuit with the other wiring diagrams since the others are for a 1992 and these are for a 1993 (most things match up, but it would be my luck to find the one circuit that changes from 1992 cars to 1993 model year).
 
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Did you check for trouble codes?

Best source for good wiring diagrams: Mitchell manual, copied at our local library.
No I didn't check for codes. I could hear that the fuel pump wasn't running, like it should have when the key was turned to the on position, so I immediately started there...

Thanks, I'll have to see what is available in my library.
 
I have diagnosed fuel pumps before by removing the relay and using a mometarily closed switch with two wires ending on spade terminals to emulate it. So all I had to do was turn power to car on and press button. If I could hear pumps working, I knew the problem was relay or before it. If not, I would then check power at the pumps to see if pump or wire.

If the above works, then a multimeter or a light bulb with two spade terminals would double as the signal circuit of the fuse.
 
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