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Honda BF50d stuttering/bucking

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sillboater

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I recently purchased a 16.5ft Lund Angler with a 2018 Honda BF50d. Initially, it had the insulator/grommet issue and bad gas. Don’t know how long sitting. Gas was brown! But didn’t smell like varnish. (Thanks to everyone who contributed to threads about the grommet issue and really helpful video jermbos!) The VST appeared immaculate inside. My current issue is when I am cruising along and give her the beans, it stutters and bucks. If I gently give it gas, it does much better, but eventually starts the bucking and bouncing. It doesn’t die out. It has an 11.4 x 12p prop. Transom is 20.5in and motor is mounted as low as it will go on transom. It doesn’t seem to matter if it’s trimmed all the way down. Cavitation, HP fuel pump, too low of a prop causing over rev? Any help appreciated!
 
Hi,

I don't know how that outboard should be propped but, if the prop size was the issue, I would think it would do this all the time, not just when you "give it the beans".

Based on how you are getting the impression that it's overspeeding and hitting the built in rev limiter, the shock absorption prop hub may be failing. They're a rubber composite and could suffer deterioration if stored a long time exposed to the elements.

You might want to match mark the hub and propeller with a sharpie and take it out. If the marks are misaligned after a "bucking and bouncing" event, then the hub is likely damaged and causing the issue.

If that's not the problem, I don't know what else to check although you're description of "brown fuel" has me wondering how the fuel injectors may have been affected. Especially if you tried running it without first flushing the lines and fuel rail first.

Just a couple of thoughts.

Good luck.
 
Thanks jgmo, I’ll try marking the hub and prop. Yes, unfortunately I ran the motor before I realized the state of the gas. I didn’t go far because of the grommet issue, but I guess the damage may have been done. It idles pretty good and light to medium throttle runs good. Hard throttle and full speed causes what I am calling the bucking or momentary sputter. I’ll update after next trip to the lake
 
It doesn't really sound as if the injectors are damaged to me. I meant that it's possible that there may be some lingering trash in the rail or the injector "baskets" (the filtering screens that most injectors have) causing stuttering and bucking.

Hope your ride goes well and look forward to your report.
 
Thanks NSDON, I plan on taking her out for a spin tomorrow (Saturday). I’ll load up a gallon of gas with sea foam for the ride. Like you said it can’t hurt and might cure it.
I took the prop off and marked it to tell if the hub is slipping. The hub looked intact though, but I guess looks can be deceiving.
 
Whoops forgot to hit send yesterday on previous post.
Well, took her out to the lake today and ran Seafoam thru ( 3/4 gallon gas & a can of Seafoam).
I couldn’t tell any change. Still has the same issue. A quick pulsing/ surging at higher speeds might be the best description. It goes away when I let off the gas. Low and midrange is fine. The prop + hub marks were still lined up, so no slipping.
I’m glad I got out there today though, weather was beautiful.
 
sillboater said:
I recently purchased a 16.5ft Lund Angler with a 2018 Honda BF50d. Initially, it had the insulator/grommet issue and bad gas. Don’t know how long sitting. Gas was brown! But didn’t smell like varnish. (Thanks to everyone who contributed to threads about the grommet issue and really helpful video jermbos!) The VST appeared immaculate inside. My current issue is when I am cruising along and give her the beans, it stutters and bucks. If I gently give it gas, it does much better, but eventually starts the bucking and bouncing. It doesn’t die out. It has an 11.4 x 12p prop. Transom is 20.5in and motor is mounted as low as it will go on transom. It doesn’t seem to matter if it’s trimmed all the way down. Cavitation, HP fuel pump, too low of a prop causing over rev? Any help appreciated!
Click to expand...
Thanks, thats my video I'm glad its helping so many people! This may have been discussed previously but did you change the high pressure fuel filter? That would be my next guess, you can change it without removing the VST, I didn't cover that in my video but it its fairly straightforward.
 
Hello jermbos. Your video was excellent and very helpful! Thank you so much.
Yes, I replaced the high pressure fuel filter. I installed a genuine Honda filter. Didn’t change the issue. I have purchased a Honda high pressure fuel pump but haven’t installed it yet. When I did the grommet repair in the vst, the pump looked good (no rust or corrosion seen) but I guess that could be deceiving? I’ve taken it out more and I think a high speed surging is a more accurate description. Thank you for your input and any ideas are appreciated!
 
sillboater said:
Hello jermbos. Your video was excellent and very helpful! Thank you so much.
Yes, I replaced the high pressure fuel filter. I installed a genuine Honda filter. Didn’t change the issue. I have purchased a Honda high pressure fuel pump but haven’t installed it yet. When I did the grommet repair in the vst, the pump looked good (no rust or corrosion seen) but I guess that could be deceiving? I’ve taken it out more and I think a high speed surging is a more accurate description. Thank you for your input and any ideas are appreciated!
Click to expand...
Thanks, I ended up doing exactly what you said here. First I did the grommet fix when I made the video, it worked but then had intermittent issues, so I changed the fuel pump. Ended up being twice the work and if the pump wasn't so pricey I would have changed it when I did the grommet. From what I've heard these motors work best with an OEM Honda pump, the aftermarket stuff doesn't work so well.
 
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