First time here and glad I found a source for some help! I was recently gifted a McFast 5 bass boat with a 1976 85 Hp Johnson. I put fresh fuel in it, took it to lake and it ran great, took off like a rocket, pulled into shore drank a celebratory beer then went again. The second time it took forever to get on plane and would bog down on full throttle. If I back the throttle off a little it would start to rev and eventually go but still can’t get full throttle.
I pulled the carbs and they were super clean, I went ahead and replaced all the fuel lines as they looked cracked. Checked the filter on the fuel pump and it was clean. All the linkage seems to be functioning fine. Motor starts right up with just a tap of key and idles fine. The fuel bulb isn’t collapsing and the in line fuel filter is new and clean. Plugs all look good and I’m getting spark on all four. It’s pumping water and doesn’t seem to be getting hot, a friend suggested we let it sit for an hour with the hood off to see if it made any difference, after an hour we ran it again with no change
It seems to surge as it try’s to go, I’ll feel good acceleration for a few seconds then it loses power but eventually will go but not in full throttle. I should mention it will use full throttle once in awhile but it’s rare. Top speed so far is about 35 mph (used gps on my phone) it seems like an 85 hp outboard should push this boat faster than that, had a 55 hp Chrysler push my last, heavier boat with similar hull up to 40 with ease.
I appreciate any suggestions!