1987 Volvo 780 won't run



I’ve submitted this question before but still can get the car to run. I can get it started (barely). When it does start it run very rough and only if I hold the accelerator to the floor and then it always stall out. The engine is getting gas and spark…the spark looked weak. The plugs were fouled and I put in properly gapped new ones. I’ve put in dry gas, changed the fuel filter, and inspected the distributor cap and rotor and that looks ok. HELP!


If the spark looks “weak”, it could be those old spark plug wires, distributor cap and rotor. Just for funzies, also, change the engine coolant temperature sensor (the one feeding the engine computer, not the one feeding the dash gage).


It’s getting gas, but at what pressure?

You also need to make sure, by carefully listening or using a NOID light, that the injectors are pulsing.

I ran into a Volvo once that had developed an ECM glitch and it was keeping the injectors open all of the time. That was a very unusual thing to happen and I’m not saying that it’s the case here; just pointing out a possibility.


hellokit & ok4450, thanks for your advice