1975 70 hp Johnson won't start

[no clue]

Hey guys/gals, I'm new at this and have a problem with my 1975 Johnson 70 hp engine. I purchased this last year (sitting in a yard, uncoverd for several years) and re-furbished the boat, cleaned the carbs and replaced the fuel pump and gaskets. The engine would start and run, but when on the water, I couldn't get it to "open up", it would only run about half it's potential (if that). Now I can't get it started. A mechanic has it, and is telling me it has plenty of spark, but he can't get it to run and doesn't know what else to look for. Can anyone steer me in the right direction, or provide any suggestions. My son and friend are pretty good at troubleshooting and have worked on boat engines, but don't know what to look for. Thanks in advance for any help.

 

[martino1]

To make it run, you need fuel, compression, and spark, and all at the right time. First thing you desperately need is a new mechanic if yours "doesn't know what else to look for." As a starting point, I would do is a compression check on all cylinders