90hpJohnson20032stroke
Recruit
- Joined
- May 3, 2014
- Messages
- 4
Struggling to get my boat mechanic's attention, so trying to diagnose myself. I'm pretty good with fixing if I understand the problem, so thank you for any help you can offer.
My motor is a Yamaha 2007 F150 4stroke, and it's on a 2007 21 Sea Hunt BXT. (my user name is from my old boat, can't figure out how to change that)
I noticed bad shaking at about 3800 rpms last trip out (that's my normal cruising rpm). Cycling through different rpms while on plane, I could find spots intermittently that didn't shake as bad, but it only runs smooth when I get over 4k and runs smooth to WOT.
I first thought it might be a fuel supply issue, so I did the annual service (separator, fuel filter change, etc) that was needed anyway and also went ahead and changed the spark plugs to be sure those are good. Shaking still there.
Then realized (duh) I should test engine without it in gear - no shaking when cycling very slowly through all rpms to about 4k. So, now I think it's a drive or prop issue - prop looks good to me, but I've only eyeballed it.
Also, about a month before this started, I noticed the engine bogging/stalling when shifting slowly up from idle speed (bottom rpm in gear). I have to throttle up/down quickly to avoid this. If it could still be an engine issue despite no shaking when not in gear, any connection here?
Any thoughts are really appreciated!!
My motor is a Yamaha 2007 F150 4stroke, and it's on a 2007 21 Sea Hunt BXT. (my user name is from my old boat, can't figure out how to change that)
I noticed bad shaking at about 3800 rpms last trip out (that's my normal cruising rpm). Cycling through different rpms while on plane, I could find spots intermittently that didn't shake as bad, but it only runs smooth when I get over 4k and runs smooth to WOT.
I first thought it might be a fuel supply issue, so I did the annual service (separator, fuel filter change, etc) that was needed anyway and also went ahead and changed the spark plugs to be sure those are good. Shaking still there.
Then realized (duh) I should test engine without it in gear - no shaking when cycling very slowly through all rpms to about 4k. So, now I think it's a drive or prop issue - prop looks good to me, but I've only eyeballed it.
Also, about a month before this started, I noticed the engine bogging/stalling when shifting slowly up from idle speed (bottom rpm in gear). I have to throttle up/down quickly to avoid this. If it could still be an engine issue despite no shaking when not in gear, any connection here?
Any thoughts are really appreciated!!
