2010 Honda BF90D Issues

Dcav66

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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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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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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

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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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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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Dcav66

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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.
Continuing to eliminate things. Yesterday I checked the high pressure fuel filter. To my surprise, it was completely black and had a fine Sandy grit all over it. Apparently it was never changed - probably ever. I assumed when the shop did the complete service in June, they did all the basics like both fuel filters, both thermostats, etc etc. Probably bad for me to assume that. In any case, I changed it out and ran the boat for quite a while today with no issues. I will need to run it a few more times to feel confident that the height pressure fuel filter was the problem. I do still plan on changing out both thermostats because I’m not confident my shop did both. Thanks for the tips and I will let you know how things turn out.
 

Dcav66

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Update - changing the High Pressure fuel filter definitely helped, but the problem seemed to return. I also changed out both thermostats. Still same issue, but seems a little different and slightly better. Next I will change out water separator on the motor which has a water sensor. Even though the on motor water separator is clean and clear of debris/water, I’m thinking the sensor or float might be acting up. Also going to change out High Pressure fuel pump while I’m at it. I also plan on changing out water release valve at the back/bottom of the motor because I noticed lots of gunk buildup when changing out the thermostats.
 

Dcav66

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Update #2 - I pulled the VST and wouldn’t you know this thing is a total mess. High Pressure pump is rusted out. Rust particles all in the HP housing and also in the VST tank. Water cooler housing is nasty greasy and doesn’t even look like water is circulating through there. Just crud in every corner. Pictures don’t do it justice. CFE7C95F-FA73-4674-9B8F-885C0AB0BCF8.jpeg24BC70FC-B8DC-4E88-9C3B-0D7DE0E8344A.jpeg35E14CFA-6261-412F-A12F-0D90B3F4A30D.jpeg41E70503-197D-46C1-9724-64C2E98B43C0.jpeg01F91E41-29E8-4F1B-AE0F-4A9A07A95E8D.jpegD664A105-142F-44E4-8F0A-B520A575EACE.jpeg37E5071D-D1BD-4E45-ACE7-6BC6369E6DDF.jpeg8C385415-A620-4D75-89FF-4EC6B65B7D83.jpeg2735EE75-D719-4EE1-8249-22B0DFC5E5A7.jpeg93381AE7-0593-49BE-BD25-E9DE5E8C3917.jpeg
 

Dcav66

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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?
I did end up replacing both thermostats with the correct ones. The shop only changed one and not the other. The one they didn’t change, was the wrong one as far as temp rating. I found a separate issue with the built in flush port being clogged and still working through that issue posted in another thread. Additionally I found the VST is a mess and the high pressure fuel pump was rusted out....see below.
 

ahicks

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GOOD JOB! Congratulations on discovering your issue! It's stuff like this that reinforces my hate/distrust of dealership work.

2 things. First, the pump's female electrical connectors look terrible in the picture. I would make sure those were spotless prior to reassembly.
2nd, the rubber grommet arrangement on the outlet side of the pump has caused a lot of headaches. I would replace it, and when reinstalling, place it on the pump outlet ti install. Do not leave it as it is and insert the pump into it. Very often it will distort if you do that, effectively blocking the fuel flow. -Al
 

MattFL

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Nice work, it sounds like you've most likely found the problem.
 

Dcav66

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Issue resolved – It turns out there was a ton of junk in the VST from a rusted out High Pressure fuel pump, which also clogged the injectors. I cleaned the VST, changed the HP fuel pump, changed the HP filter, changed the injectors....all good now! Here is a video that describes what I did:
 

Dcav66

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Jul 26, 2020
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GOOD JOB! Congratulations on discovering your issue! It's stuff like this that reinforces my hate/distrust of dealership work.

2 things. First, the pump's female electrical connectors look terrible in the picture. I would make sure those were spotless prior to reassembly.
2nd, the rubber grommet arrangement on the outlet side of the pump has caused a lot of headaches. I would replace it, and when reinstalling, place it on the pump outlet ti install. Do not leave it as it is and insert the pump into it. Very often it will distort if you do that, effectively blocking the fuel flow. -Al
Yes sir - I cleaned everything up really really good, replaced all the rubber seals, grommets, etc. Also ensured all the electrical connectors were routed correctly inside and out. All good now...thanks!
 

backmarker

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Sep 8, 2011
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thanks! i suspect i have the same problem. Mine just started idling rough, and when you increase the throttle it just dies. Ill check all the stuff you did and thank you for the video:)
 

bloublasie

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Jun 7, 2021
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Dave thanks for your messages and videos, followed in detail.
my motor would die immediately on idle if you increase the throttle.
did the fuel system, as you did. Problem is still there. If you start with some throttle it revs up but with a very rough idle, seems to get better when the motor warms up.
 
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