I'm troubleshooting a dead 1989 745T, original post here:
http://www.brickboard.com/RWD/volvo/1289300/740/760/780/740_start_help.html

When I jump 87/2 and 30 on Fuel Injection relay board the in-tank pumps starts ONLY. No main pump. Remove fuse #11 to be sure with hand on main pump - nothing.

Question: Is there anything else to verify before I remove pump and bench test?
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Big Swede: 1989 745T 234,000KM

Gentlemen;

Thanks very much for all of your time and help. I had 87/2 + 30 jumped on the FI relay board, Fuse 11 out, and was ready to test 12V at the wires to pump. I grabbed the wire to remove and the pump STARTED BUZZING. Erg. A loose wire!

I plugged a spare connector into fuel pump wire with a meter and wiggled and twisted it about to see if it was a broken wire. Nope. The connection had come loose.

This does not instill confidence in my car's wiring. I hope this can help someone else.
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Big Swede: 1989 745T 234,000KM

Hello Norm:

On my car the fuel pump positive line was the pink one at the pump. Seems to me that you could plug your fuel system relay back in and check for voltage on this line when cranking. If you see voltage there and the pump doesn't run, then it points fairly conclusively to the pump.

Doing it with the y-jumper described below in place would rule out the fuel system relay too.

Don't buy a Carter replacement pump-- I had to because of time constraints. It is noisy compared to the Bosch, uses generic connectors and has no check valve at the output, and what's worse, you can't move the check valve over from the old pump because the threads are different.

Good luck!

If you don't mind crawling under the car just connect two wires from the pump to the battery.

Hello:

You need a jumper with two legs (courtesy of lucid, when I had trouble with my '92 940 not starting):

If you want to try jumper wiring to temporarily replace a "suspect" Fuel Injection relay, it needs to be a "Y", with 3 ends plugged into the relay socket:

Terminal 30 (Red) for the +12V
Terminal 87/1 (Orange, Brown) simulating System relay output
Terminal 87/2 (Yellow-Red) simulating Fuel relay output.

Diagnostically, it is worth trying to get your hands on a 'noid light, which will tell you whether the injectors are being pulsed when cranking. If you have spark and the injectors are pulsing, all that's left is fuel and timing, and it sounds like your timing belt is intact. Do you have fuel pressure at the schrader valve between injectors 1 & 2 on the rail?

On mine I had similar symptoms (although it was cold out). The best guess is that the car flooded, and the excess cranking washed down the cylinder walls, killing the compression. Try squirting in a couple of tablespoons of oil into each cylinder and then swap the plugs and try to start it.

Good luck!

Good luck!

I don't think Norm needs it in this case, Herb. Seems to me his relay jumpering (30 to 87/2) points pretty conclusively to the pump – except for connector "L" in the linked diagram, wherever it is.

Too bad we don't have the facing page for that diagram, although my later diagram shows the comparable connector to be at the "electrical distribution unit", which I guess is the (ugh) relay rack.