I'm a new here but have been struggling with an apparent wayward # 4 fuse or bad chip in my ECU for months, The car acts like the relay is bad when you try to start the car. (relay closes but pumps aren't working) but if you jump them (12 v to fuse #4) the car runs like a champ. Once started sometimes it will then run w/o the jumper but over a period of days, the jumper has to stay on or the pumps shut off
The Volvo guy also reworked the fuse block and relay wiring and got it running OK…twice… both times, for about a day.

I also check the ECU with a known good from my other Volvo (1990 240) both the ECUs run the '90 and neither will get the '92 to start.

There is no CE light on, the codes read 111. I read 12.xx volts to fuse #6 (the injector pump) but zippo on either side of #4

What's the down side of running both fuel pumps all the time with my little jumper? (fused of course). What am I hurting if I drive while I debugger this mystery?


other unrelated? ongoing work recently completed:
just turned 100,000 miles:
new in tank pump/ sock.
filters (air, oil, fuel)
plugs, wires, rotor,cap
removed an old low jack I found.
New muffler (welding involved)
alignment,tires, balance.
door speaker replaced
The injector pump looks to be less than two years old, and the previous owner had the car dealer serviced since it was new. Even the belts said Volvo.