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I was gifted a Volvo and it hasn't been used since 2014. I took it to a mechanic and paid for new spark plugs, new injectors, new fuel pump, and new alternator. All that and it still turns off. I checked everything, but I believe the Injectors aren't receiving electricity and I believe the ICU (Ignition Control Unit) is the reason why. Is there somewhere I can get that part? Or possibly fix it myself internally? All the youtube videos I've seen only talk about the ICM (Ignition Control Module) but they describe the same issue.
turbo/non turbo? Regina or bosch ignition if not turbo?
Volvos in that year range have a couple of relays that control power to the fuel and ignition system. It is common for cracked solder joints to happen in them - and when the relay gets hot - those cracked joints become an open circuit. Car dies and starts back up when they cool down. Rarely have I replaced an ICU on those cars. (the ecu fails on a couple of years and fails to turn the fuel pump on) The relays always crack in the same place - so if you find someone who knows old Volvos - they will know exactly where to look. A magnifying glass is needed unless you are very near sighted - Other possibilities could be engine speed sensor, or ignition amp (if bosch ignition)
A 1991 has the early OBD system - codes can be accessed under the hood that might provide clues. What codes do you have? If you "believe" the injectors are not getting power - simply plug your $8 noid light in and check that. (by the way the injectors are powered from the fuel injection computer, not the ignition computer) - Your you tube videos might be related to the ICU used in many 240s - those WERE known for cracked solder connections.
There is a fuel system relay in the fuse box (square black or rectangular white depending on fuel system) and most have a noise suppression relay under the hood. The noise suppression relay powers the injectors on some cars - moving the electrical noise they create away from the radio. Noise suppression relay might be mounted near the RF corner of the car.
Sometimes the wiring is damaged to the underhood relay - this guy has replacement parts
1991 Volvo 740 Abruptly Turning Off
