J175GLEUC 175HP Johnson Fast Strike

by Marty
(Dexter, MI)

Just bought a used Four Winns Horizon 190 boat with 1997 175HP Johnson Fast Strike. Guy said the motor ran great. Ran it on muffs in his yard, no problems. No lake nearby to test drive it in.

Towed it 350 miles home, took on lake, and it runs a little rough at low speeds but ok. Runs great and strong up to ~3/4 throttle. Over that it bogs like it's not getting fuel. Pulled cover and airbox. All throttle plates moving in unison. Engine looks like new under the cover. No marks on bolts as if it's been worked on, etc. Contacted the seller. He insists it worked perfect last year, but he won't commit that he went full throttle. Says he went about 30 mph and "that was fast enough". Sounds like BS to me and now I'm stuck.

Any ideas on how to troubleshoot and fix this bog?

Marty



Compression was between 92 and 98 on all cylinders. I don't have the record of which cylinders had which compression.