2010 Honda BF90D Issues

Dcav66

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Jul 26, 2020
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Bought a used 2010 17ft skiff with a Honda 90 with less than 300 hours. Had a full service done on it immediately. No issues found by the shop. Everything seemed to be fine and it purred like a kitten. Took it out on a local lake and idled around quite a bit perfect. Then I opened her up and after about 15-20 minutes of running around 4-5k rpms it started started having issues. It would lose power and go into limp mode. Turned it off and back on and everything was fine again for a few minutes and then do the same thing over and over. Took it back to the shop and they said it had no codes and everything ran fine - mechanic couldn’t find anything wrong. Took it out several more times after that and the same thing happed again after running at cruising speed for 15-20 min. Never a problem at idle speeds - runs for hours. I suspected a fuel issue so I installed new water separator, fuel filter, fuel pump, hoses, bulb, connectors, running non-ethanol fuel, tank vents are open and clear, no line leaks, and bulb stays hard. Also doesn’t seem to overheat, water pump is new, strong cool pee stream. Oil level is good and no alarms on console. So what am I missing - what else would cause a Honda 90 to go into limp mode after 15-20 min of running at cruising speed?

I have a recent video of it acting up but can’t seem to post on here.
 

ahicks

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Sep 16, 2013
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3,010
It's almost surely a cooling issue. Did the shop install a new thermostat? Did they check the by-pass valves?

Do you (or the shop) have one of those infra red thermal sensors you could use to see how hot it's getting?
 

Dcav66

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Jul 26, 2020
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Interestingly enough, there was a bad thermostat identified and the shop said they replaced both thermostats during the first service when I got the boat back in June. Definitely makes me wonder if they really did or maybe just one and not the other. Something I will look into...thanks!
 

Dcav66

Cadet
Joined
Jul 26, 2020
Messages
8
It's almost surely a cooling issue. Did the shop install a new thermostat? Did they check the by-pass valves?

Do you (or the shop) have one of those infra red thermal sensors you could use to see how hot it's getting?
Is it normal for the water to stay cool/cold coming out of the motor? Just doesn’t even seem warm to the touch.
 

ahicks

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Sep 16, 2013
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3,010
Is it normal for the water to stay cool/cold coming out of the motor? Just doesn’t even seem warm to the touch.
I don't remember how the 90 is set up, but on some motors, that water doesn't circulate through the motor before exiting there. I do know luke warm water isn't unusual. If you're getting a buzzer, I would not use the temp of that water to discount an overheating issue.

There is also the possibility the temp sensor is throwing a false signal, due to a bad sensor or bad/erratic wiring connection. I struggle with that a bit (bad connection), as it takes so long to happen (20 minutes).

Worth considering too, is a lesson I learned on a 50hp engine not too long ago. The thermostats on the injected engines are rated for cooler temps (160 if memory serves me) than the older carbed engines (180) - and they look identical. If a tech just walked to a parts bin and picked up a new t-stat, he could easily have picked up the wrong one(s). That's easy to verify, and worth the trouble on an issue like this one. Look at the bottom of the t-stat. Temp is marked in celsious.
 
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