Re: 86 force 125 low compression in one cylinder
The best thing to do in these matters is to think systematically. Eliminate one thing at a time and note any differences.
From my own experience, I found that replacing the fuel pump wasn't enough but I didn't look further in the fuel pump area. I went on to rebuild carbs and replace fuel line etc. but still had running problems. It turned out to be the three check valves in the pump were sticking.
I would suggest that your engine is leaning out and you should start with the fuel system. Clean the carbs out good with some WD40 or carb cleaner. Also, low compression can play hell with your fuel pump as it uses compression to operate. What is the fuel ball condition when this is happening? Is it still hard, collapsed, soft?
Why don't you clean out the carbs, clean the plugs and give it a Seafoam treatment and then check back.
Regards,
John