I could really use some advice.

Car is a '78 245- donor engine is from a '76. Completed the job about a week ago.
I haven't got the book on the car and only a few sketchy schematics...

Periodically (3 times in the last week) the car has stranded me- I'm not used to volvos doing this.

Just be motoring along (exterior temp around 100f- having a heat wave) and it will stop making spark...

Thought it was heat related- now not sure.

Swapped out ignition module with one from donor car- car started.
Discovered coil wire to be a little loose- car started.
fiddled pointlessly- car started.

Getting juice at the coil inputs.

Not always getting spark.

I have the fuelpump relay sort of hotwired at the moment. (yellow to red). There is a bit of excess noise out of the pump, and some hesitation that I think is also pump related, but I don't think this is the big problem...

I think something is reacting to either heat or vibration?
Alternator seems to work- but I haven't tested output voltage with a meter.
Have swapped ignition module once.
Most of the original wiring looks like it has not been messed with.
Distributor looks OK, but I'm new to stuff without points....

Plan on going through the thing with a meter and test light today- but I could use some hints about where to look. When it runs, it runs fine except for the stuff I've mentioned

I've heard about the "mystery fuse" that is supposed to be either down near the battery or over near the coil.

Possibly unrelated: Yesterday- after stranding me and then deciding to run enough to get home, I noticed that the headlights had quit. Whilke I was waiting for it to cool down today I swapped out the headlight relay- no change....

Not sure what I'm missing- thing seems almost totally random at the moment...

Joe
'62 P1800
'78 245
Never buy a car you haven't test-driven....