Honda BFP60A will not exceed 3800 rpm

[Oldone88]

The engine is located on a 25' pontoon.. I purchased it during the winter from a rental company. I did not take a test ride due to the weather at the time. just ran the boat on the hose and it sounded great. after taking the boat out a few times, it will not accelerate past 3800 rpm. The rental company says that it should run about 5800 rpm. I ran a compression test and the three cylinders from top to bottom were 165, 165, and 170. Also ran a fuel pressure test and it was in spec, 41, with a range of 41-45. The FPR seems to be working well, drops fuel pressure to about 34-35 at idle. I performed a fuel pump volume check, it checked good. It has a throttle stop to limit max throttle. I took the air cleaner off yesterday, and the butterfly at WOT was around 3/4 open. i backed the throttle stop off till it the butterfly was almost full open at WOT. took the boat for a run this morning and it ran exactly the same. runs up to 3800 rpm, but i now could push the throttle farther but it didn't affect performance. The engine is fuel injected. It has brand new spark plugs in it, and since all of the fuel checks yesterday I've ordered new fuel filters. Except for not exceeding 3800 RPM the engine starts and runs great. Any ideas?

 

[MattFL]

Does the rental company have any other similar boats with the same motor for rent? If yes, go take one for a spin and see how it performs. If it's better, compare the prop on your boat to the prop on the rental. My point is, if the motor appears to run fine otherwise and there's nothing obviously wrong with it, double check the prop. Taking a total stab in the dark, maybe the rental company swapped the prop on the way out the door to keep the lower pitched prop for their next boat and put the original higher pitched prop back on the motor. Worst case, there should be some online prop calculators that can help you get a ballpark for what your prop should be and you can compare to what's on there now just to see if it's remotely close. A 25' boat is a lot of boat for only 60HP so I would expect a fairly low pitched prop to be on there.

A maybe not useful comparison, but I've got a 50HP Honda on a 17' boat with the stock prop and if I'm towing something that takes a hot minute to get going (towing a tube, wakeboarder, boat full of people, etc..) then 4k-ish RPM is about where it sits until the boat starts to plane out, which makes me think that your motor might be running fine and could just have the stock prop on it and is just struggling with such a big boat due to too much prop.

 

[Oldone88]

I believe they have upgraded and sold all of their old inventory. But I do understand that this boat is a big boat for only a 60hp, it almost kept me from buying it. But I’m not really looking for speed, just want the motor to reach its cruising rpm. The prop is a stainless Honda prop 3x14x11. I’m pretty sure it’s the one that came with the engine. Not sure if that’s low pitched or not, I’ll have to try and find a good calculator.

 

[MattFL]

There is a prop calculator on the Honda marine site, but it seems useless.

Edit--> I read the wrong motor. If I'm reading this right, for your BFP60 for a 25+ foot pontoon they're recommending 14x11R so that sounds like you should be right.. hmm...

https://www.generalpropeller.com/pdf/QS_Honda.pdf

 

[Oldone88]

I believe they have upgraded and sold all of their old inventory. But I do understand that this boat is a big boat for only a 60hp, it almost kept me from buying it. But I’m not really looking for speed, just want the motor to reach its cruising rpm. The prop is a stainless Honda prop 3x14x11. I’m pretty sure it’s the one that came with the engine. Not sure if that’s low pitched or not, I’ll have to try and find a good calculator.

Thanks for working the calculation out. I looked at quite a few of those prop calculators, including the Honda one but couldn’t find the answer I was looking for. Yeah I’m perplexed as well. I’m going to change all of the fuel filters when they get here, and I’ll report back if that changes anything. Might have to start looking at the injectors.

 

[MattFL]

If you look at the spark plugs, does it appear that all cylinders are firing?

 

[ahicks]

Based on practical experience, that prop is about right, and should run the boat up close to 20mph - assuming it's lightly loaded.

This 3800 rpm issue is why I like the carbed motors much better. They don't play games like this. Fuel injected start and run better of course - until they don't....

That said-

Have you had the vapor separator apart on this motor? If so, a lot of us, myself included, have had trouble with this stupid grommet. It gets wadded up during the re-install of the pump, and blocks or partially blocks fuel coming from the pump to the filter. If partially blocked, it could be OK up to 3800 rpm for instance, then starve the engine preventing it from turning any faster.

Check out #28 in this diagram for the grommet I'm speaking of:

https://www.boats.net/catalog/honda/outboard-by-year/2007-and-later/bfp60ak1-lrta-vin-bbfj-8100001-to-bbfj-8199999/vapor-separator

If somebody doesn't know any better, they will likely install this thing into the top of the separator body, then insert the pump into that. That's almost guaranteed to push the grommet in way too far, blocking the outlet in the process. You have to install the grommet on the pump, then install! This will allow everything to settle into place as designed. Judging by the amount of trouble it's caused, it's a clearly a dumb design. Guys have pulled their hair out diagnosing this issue..... -Al

 

[Oldone88]

If you look at the spark plugs, does it appear that all cylinders are firing?

I checked them yesterday and they all looked good.

 

[Oldone88]

Based on practical experience, that prop is about right, and should run the boat up close to 20mph - assuming it's lightly loaded.

This 3800 rpm issue is why I like the carbed motors much better. They don't play games like this. Fuel injected start and run better of course - until they don't....

That said-

Have you had the vapor separator apart on this motor? If so, a lot of us, myself included, have had trouble with this stupid grommet. It gets wadded up during the re-install of the pump, and blocks or partially blocks fuel coming from the pump to the filter. If partially blocked, it could be OK up to 3800 rpm for instance, then starve the engine preventing it from turning any faster.

Check out #28 in this diagram for the grommet I'm speaking of:

https://www.boats.net/catalog/honda/outboard-by-year/2007-and-later/bfp60ak1-lrta-vin-bbfj-8100001-to-bbfj-8199999/vapor-separator

If somebody doesn't know any better, they will likely install this thing into the top of the separator body, then insert the pump into that. That's almost guaranteed to push the grommet in way too far, blocking the outlet in the process. You have to install the grommet on the pump, then install! This will allow everything to settle into place as designed. Judging by the amount of trouble it's caused, it's a clearly a dumb design. Guys have pulled their hair out diagnosing this issue..... -Al

I pulled the high pressure filter out of the vapor separator last night, and it was the dirtiest filter I’ve ever changed in my life. So hopefully that may be the issue, it’s the first thing I’ve found that could possibly be a cause, everything else checks good. I haven’t had the separator apart yet, but I will definitely have a look at that grommet when I get a chance. I appreciate the suggestions.

 

[Oldone88]

And just a note on the speed of the boat, we’ve had 4 people on board, and at 3800 rpm we were at 17 mph on the gps. So 20 mph at 5800 rpm, sounds completely doable. Not so much looking for speed , just getting the engine running correct.

 

[ahicks]

Here, on a new to me boat, that would leave me wondering about the accuracy of the tach?

17 mph (via GPS) not very far off of what most boats like that will do when right. Your tach, if it's not set correctly, COULD be misleading you, sending you on a wild goose chase? There's a dial on the back of many (most?) of them, used for selecting the proper signal from the motor. Set incorrectly (causing a low reading), it's very possible you're going to get a situation very similar to what you describe.

Just a thought, but maybe if it's a fuel starvation issue, maybe you could confirm by the throttle position? In other words, if it goes up to max rpm at 1/2 throttle, and does nothing when the throttle is increased, that might be indicating fuel starvation. However, if it's not topping out until the throttle is up over 75% or so. that might have me wanting to confirm the accuracy of the tach.

Potential for a tach issue just another possible idea, not abandoning the fuel starvation idea- yet.

Hopefully the filter change will fix it.

 

[MattFL]

If you decide to troubleshoot the tach, then if you don't have a shop tach available you can get a combo tach/hour-meter on Amazon for around $20 that just wraps a wire around a spark plug lead to get its reading. Many of them will remember your max RPM (read the features before buying), so you could install it, make a run, then check if what it remembered matches what you saw on the tach. Or just rev it up a little bit on the muffs and see if the reading matches your tach.

 

[Oldone88]

I reply back when I’ve had a chance to test it. Memorial Day may be the opportunity.

 

[Oldone88]

I reply back when I’ve had a chance to test it. Memorial Day may be the opportunity.

No difference after the filter change. Engine ran about 3800 rpm flat out with 6 people on board, 15 mph. I used a stethoscope to check the injectors while idleing, and they all sounded like they were working. Back to the drawing board.

 

[Oldone88]

Based on practical experience, that prop is about right, and should run the boat up close to 20mph - assuming it's lightly loaded.

This 3800 rpm issue is why I like the carbed motors much better. They don't play games like this. Fuel injected start and run better of course - until they don't....

That said-

Have you had the vapor separator apart on this motor? If so, a lot of us, myself included, have had trouble with this stupid grommet. It gets wadded up during the re-install of the pump, and blocks or partially blocks fuel coming from the pump to the filter. If partially blocked, it could be OK up to 3800 rpm for instance, then starve the engine preventing it from turning any faster.

Check out #28 in this diagram for the grommet I'm speaking of:

https://www.boats.net/catalog/honda/outboard-by-year/2007-and-later/bfp60ak1-lrta-vin-bbfj-8100001-to-bbfj-8199999/vapor-separator

If somebody doesn't know any better, they will likely install this thing into the top of the separator body, then insert the pump into that. That's almost guaranteed to push the grommet in way too far, blocking the outlet in the process. You have to install the grommet on the pump, then install! This will allow everything to settle into place as designed. Judging by the amount of trouble it's caused, it's a clearly a dumb design. Guys have pulled their hair out diagnosing this issue..... -Al

I opened up the separator tonight and the grommet seemed to be jammed in on one side and there were a few splits in the wide part. towards the pump. i ordered a new Honda Pump and Grommet, and will report back after install and test ride.

 

[ahicks]

So SOMEBODY had that apart....
Kinda weird they wouldn't have replaced that gunked up filter. Maybe that points to whoever it was that had it apart was a rookie. Like maybe the previous owner....

Don't forget, the grommet is placed on the pump side first during the install!

Fingers crossed for you! -Al

 

[MattFL]

If that grommet doesn't do it (hopefully it will!), I just ran across this, which I've never heard of before this but apparently is a thing; on some motors if the trim sensor goes bad the computer might limit the engine RPM if it thinks the motor is trimmed up. I have no idea if this is one of those motors, but I thought it was interesting and the check is as easy as making sure your trim gauge changes when you trim the motor up and down. The info is from this video starting about 9:15:

 

[Oldone88]

If that grommet doesn't do it (hopefully it will!), I just ran across this, which I've never heard of before this but apparently is a thing; on some motors if the trim sensor goes bad the computer might limit the engine RPM if it thinks the motor is trimmed up. I have no idea if this is one of those motors, but I thought it was interesting and the check is as easy as making sure your trim gauge changes when you trim the motor up and down. The info is from this video starting about 9:15:

 

[Oldone88]

So SOMEBODY had that apart....
Kinda weird they wouldn't have replaced that gunked up filter. Maybe that points to whoever it was that had it apart was a rookie. Like maybe the previous owner....

Don't forget, the grommet is placed on the pump side first during the install!

Fingers crossed for you! -Al

thanks

 

[Oldone88]

If that grommet doesn't do it (hopefully it will!), I just ran across this, which I've never heard of before this but apparently is a thing; on some motors if the trim sensor goes bad the computer might limit the engine RPM if it thinks the motor is trimmed up. I have no idea if this is one of those motors, but I thought it was interesting and the check is as easy as making sure your trim gauge changes when you trim the motor up and down. The info is from this video starting about 9:15:

Mine doesnt have a trim guage, but i will try and verify if there is some type of trim feedback loop to the computer.

thanks