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~ 2006 Honda BF225 Extreme bucking around 2700 RPM

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BiglarinVancouver

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this site is fantastic.. have had many years of big dollar savings from you guys - thank you very much for what you do

i am quite mechanically inclined but sometimes have the typical tendency of throwing parts at things in hopes of fixes.. can use help as to diagnostics here please..


Ran great last three years.. first time out this year about a month ago, experienced hard bucking and will not get up on plane.. relatively extensive list of what I've completed this year to no avail:
1. determined Racor was creating air vacuum leak by using clear line and seeing extensive bubble so bypassed it, no air leaks pre motor now
2. still using existing fuel line from tank but have connected it to new fuel line where tank line comes out of hull to primer bulb
- also new fuel lines from primer bulb to onboard water separator, to low pressure filter, to hard fuel line where the low pressure filter connects to ( hard line pretty much located from under onboard water separator around rear of motor.
3. new primer bulb
4. new low and high pressure fuel filters ( with new orings on each)
- have verified no fuel leaks from either especially at HP filter housing as sometimes tricky to avoid misinstall of that cover
5. have drained VST three times
- first time i drained it this year, had about a cup of relatively 'brownish' color fuel (thinking stale)
- then absolutely fresh fuel from VST during that first flush as was pumping bulb to 'flush through'
- second and third time draining VST, beautiful clear fuel coming out / absolutely no water in it
6. last night on water, ran from auxilliary motor / separate tank ( with super rich seafoam additive thinking maybe might eat through any contaminants in VST needle leading it to stick etc.).
- ran this line directly to onboard hard line, so bypassing all onboard filters
- used clear line and no bubbles
- ran about 3 gallons of this fresh fuel / seafoam witch's brew to no avail - still bucking
7. I have the DR Honda software
- hooked up multiple times
- first showed O2 sensor error so I swapped that out - no fix
- Ran different graphs / sensors check during bucking episodes
- pump bulb full, go to get on plane and when hits 2700 RPM ( may vary a bit) she starts to buck
- software just shows that IAC valve has a continuous value of 1.0, not varying between 0 and 1.0 at all
8. Bucking will somewhat smooth out when continuously pumping the bulb
9. Hooked up Fuel pressure gauge and getting 37 PSI at HP filter bolt / port when idling ( both in and out of gear)
- cannot check fuel pressure when motoring / under load as need to have lower cowlings intact when doing so


10. thinking either a few internal fuel line air sucking leaks or possibly low pressure pump weak????

11. VST
- thinking posibly either needle or float possible issue as seems to start bucking once the VST has 'run dry'.. about 3-4 seconds of increasing throttle significantly

Boat is in water at marina and is pretty much a day long procedure to get back on trailer and into my shop and pain in the butt to remove VST in the slip

think it's strictly low pressure side air leak/ upstream from VST? high pressure pump screen restricted?

Bucking goes from 2700 rpm back down to about 800 in specific one second intervals.. seems like all or nothing for fuel


Sorry for extremely long note here but wondering if ANYONE here might have any other suggestions as what else to tackle prior to tearing into VST.

Thank you
 
Well you sure have done a lot. I trhink you will likely need to pull the boat to check out more things.

A few things come to mind....

1. You wrote: "Bucking will somewhat smooth out when continuously pumping the bulb." I would remove the LP fuel pump and check it thoroughly. You can do that by pumping the part that sets on the cam. There is a procedure in the shop manual for testing the flow, but I will need to look that up and get back.

2. You didn't mention anything about the fuel pressure regulator. The 37 PSI for fuel pressure is out of spec - too low, but probably not low enough to cause the problem you are describing (but I'm not sure about that.) It should be between 41 and 48 PSI with vacuum hose to the regulator plugged or clamped closed and engine idle at 600 rpm +/- a bit. Did you thoroughly check the vacuum hose to the regulator? Also, there is a return fuel return hose from the regulator back to the VST. Check that thoroughly.

3. Consider removing the fuel regulator and giving it a thorough cleaning with carb cleaner. Some folks on this forum have said that there is a fuel screen inside it which can get clogged. Either way, carb cleaner should clean everything out.

4. Low fuel pressure from the HP pump COULD be due to a partially clogged fuel screen on the bottom of the fuel pump holder. It's a PITA to remove. But, if all else fails, remove it and check. Make sure you have a replacement holder on hand, because they tend to break when removed.

5. Finally, there is yet another fuel screen on the post side fuel pipe that feeds the injectors. Remove and check that. See Part #4 at:
 
chawk_man said:
Well you sure have done a lot. I trhink you will likely need to pull the boat to check out more things.

A few things come to mind....

1. You wrote: "Bucking will somewhat smooth out when continuously pumping the bulb." I would remove the LP fuel pump and check it thoroughly. You can do that by pumping the part that sets on the cam. There is a procedure in the shop manual for testing the flow, but I will need to look that up and get back.

2. You didn't mention anything about the fuel pressure regulator. The 37 PSI for fuel pressure is out of spec - too low, but probably not low enough to cause the problem you are describing (but I'm not sure about that.) It should be between 41 and 48 PSI with vacuum hose to the regulator plugged or clamped closed and engine idle at 600 rpm +/- a bit. Did you thoroughly check the vacuum hose to the regulator? Also, there is a return fuel return hose from the regulator back to the VST. Check that thoroughly.

3. Consider removing the fuel regulator and giving it a thorough cleaning with carb cleaner. Some folks on this forum have said that there is a fuel screen inside it which can get clogged. Either way, carb cleaner should clean everything out.

4. Low fuel pressure from the HP pump COULD be due to a partially clogged fuel screen on the bottom of the fuel pump holder. It's a PITA to remove. But, if all else fails, remove it and check. Make sure you have a replacement holder on hand, because they tend to break when removed.

5. Finally, there is yet another fuel screen on the post side fuel pipe that feeds the injectors. Remove and check that. See Part #4 at:
Click to expand...
fantastic.. thanks alot for your effort here chawk_man..
Based on your comments - i'm first going to thoroughly check the Fuel Pressure Regulator as easily done when in the slip.. good point - am wondering if something may have happened to the line when removing / reinstalling the motor cover.. without it in front of me, i am pretty sure this is accessible without getting under the intake manifold so i'll work to remove and thoroughly carb clean too etc.

here's my specific responses to your points:

1. i will check my shop manual and i believe there's a reading as to how much fuel output after 2 seconds of turning over the starter ( with kill switch of course removed). can that be checked by simply removing the HP filter 'port / bolt'? or?
2. FP regulator is my first plan of attack here as mentioned above
3. same as above
4. i do have a used low pressure fuel pump and new HP Fuel pump being delivered by Monday the 12th so i will have to wait til then to get boat out of water to perform the VST stuff if required.. i've removed it three years ago and cleaned up the screens i could get access to as had similar / but less bucking problems before and thought it was hp pickup screen.. they were in not bad shape as i run a Racor as well but was pinhole fuel line air leak at onboard water separator.
5. will check if / when boat has to come out of the water.
question: i haven't swapped out the fuel line that feeds into the Low Pressure pump.. yet.. seeing as motor is roughly a 2006, do those lightweight 'pincher' stock connectors eventually lose their pinch? these are the type of connectors that are removed by just squeezing the clamp with pliers then sliding back down off the hose..
- i am thinking of somehow jury rigging a regular hose clamp onto the low pressure pump's inlet hose to clamp er down / alleviate air intrusion - think that might help?

FWIW, not sure it's relative for you but the boat is a '95 23' Excel Walkaround

thanks again..
 
also.. when i open the fuel pressure relief port on HP filter housing after turning off motor a short 20-30 mins beforehand, there is no pressured fuel ( or air) spitting out for the typical 1/2 second or so.. knowing this, do you think it's more fuel line air leak somewhere getting into the system?
 
When I think of bucking, I lean more towards an electrical issue as opposed to a fuel delivery issue.

I would start by checking grounds, broken spark plugs, or broken coil packs
 
codycat said:
When I think of bucking, I lean more towards an electrical issue as opposed to a fuel delivery issue.

I would start by checking grounds, broken spark plugs, or broken coil packs
Click to expand...
thank you codycat: bucking is extreme.. pretty much like key on / key off scenario.. from my knowledge, abrupt engine problems are electrical and sputtering / coughing is fuel related.. she has a distinct on/ off bucking with roughly 1/2 second / very methodical intervals.. the catch here is seems to have some 'better' power when pumping bulb when starts bucking like that.. tricky to fully test as on my own doing this and don't want to test at WOT
 
i clicked submit too quickly.. here's my 'repost'.. thanks..

thank you codycat: bucking is extreme.. pretty much like key on / key off scenario.. from my knowledge, abrupt engine problems are electrical and sputtering / coughing is fuel related.. she has a distinct on/ off bucking with roughly 1/2 second / very methodical intervals.. the catch here is seems to have some 'better' power when pumping bulb when starts bucking like that.. tricky to fully test as on my own doing this and don't want to test at WOT as obviously dangerous..

i appreciate your feedback and am going to redo main engine cables to battery - both pos and neg..

fwiw, with my DR honda software graph readings, it still shows that battery at 14.2 V when the bucking occurs.. my logic tells me that would drop to zero if overall engine ground issue... ?? maybe not?

Thanks - given this info, any further input is welcomed..



I am getting to the slip today to:

1. splice on new cable ends to battery

2. remove / thoroughly clean fuel pressure regulator as per chawk_man's suggestion

3. remove and check spark plugs for discoloration ( thinking not the issue though as bucking is too extreme for just one or two cylinders to be down)

4. put on hose clamp at low pressure pump inlet as still original 'wimpy' spring steel 'pincher' clamp
 
also.. my green oil light is off on my 4 (?) light key panel.. panel is not new by any stretch and am thinking that just the stupid led is out.. hopefully..
no alarms at all though when bucking.. from my understanding, if oil pressure is low - both the green light goes out AND buzzer too so this is why i'm thinking is just the light..
having said this, here is the graph with my DR Honda sofware when running / bucking over the 400 second run.. if anyone has input as what to better show with onboard sensors in this graph when bucking, i can easily upload a snapshot of a new graph.

thanks..

1723215242669.png
 
As you stated, if a ground issue, it should show in the voltage test, but I have seen stranger things.

I'd really inspect all spark plugs and coils
 
It sure hits a wall at 3000rpm, on my old single coils engines, I’d be looking at a coil. How many coils on this 2006?

As I understand it, these outboards won’t run off the alternator when you disconnect the battery, like my old engines do, maybe this is a bad battery cable, rusty inside a nice looking cover. The load gets large enough at 3000 to overpower the weak spot in the cable, rpm drops instantly, enough to carry the load again?
 
Thank for all the responses and input guys..


As an update, after swapping my last remaining 'last/ pre motor ' fuel line from tank to primer bulb and still problems

- during that run test on the water, same problems of falling flat on it's face in a somewhat methodical 1 second intervals of running like new, then 1 second absolutely no torque ( cycling between 3,000 down to ~ 1000 then back up to 3K - pretty much instant on/off/on repeatedly for as long as i hold on the throttle either half way or full - doesn't matter except when full throttle, she'll try to get higher rpm)- this only happens when trying to get up on plane.. cannot get out of the hole as only up to about 13mph these days..

when idling in gear, runs fine - i then repressurize the bulb with about 10 pumps to ensure she's primed, then give 'er.. runs fantastic for about 4-7 seconds then falls off.. is only better ( pretty much normal runnjing) when priming fuel bulb consistenly.. i believe all is air tight from primer bulb to low pressure fuel pump as when squeezing bulb, i can feel each cycle ( slightly) of the LP pump cycling.. maybe .. maybe not air leak..

- boat is now outta slip and in garage - in case you're interested, here's my to do list now that i can access the motor:

remove intake and all that fun stuff, replace fuel line that goes into low pressure fuel pump, test / swap low pressure fuel pump, remove / clean / reinstall fuel regulator, ohm test fuel line cutoff solenoid ( sits low in motor cowling so possible saltwater residue contamination), reluctantly remove / clean vst ( i have a new hp pump to go in if needed)

- am thinking lp pump as not keeping the vst tank full on it's own without priming at bulb.. wondering as may too possibly be float needle problems as maybe only opens that vst inlet when more fuel is pushed in when priming


going to cut back battery leads as well about 4" in case of oxidation creating too much resistance under load.. a bit skeptical about that as runs better with primer bulb squeezing but of course this should be regular maintenance anyhow when on salt..


Thanks again for all the inputs here - I know i kinda ramble sometimes but wanted to be thorough with my posts and providing an update here as to work in progress in case lessons learned by lurkers as this moves along

- will be in touch soon .. most likely 3-4 days of wrenching in between work / family life
 
BiglarinVancouver said:
Thank for all the responses and input guys..


As an update, after swapping my last remaining 'last/ pre motor ' fuel line from tank to primer bulb and still problems

- during that run test on the water, same problems of falling flat on it's face in a somewhat methodical 1 second intervals of running like new, then 1 second absolutely no torque ( cycling between 3,000 down to ~ 1000 then back up to 3K - pretty much instant on/off/on repeatedly for as long as i hold on the throttle either half way or full - doesn't matter except when full throttle, she'll try to get higher rpm)- this only happens when trying to get up on plane.. cannot get out of the hole as only up to about 13mph these days..

when idling in gear, runs fine - i then repressurize the bulb with about 10 pumps to ensure she's primed, then give 'er.. runs fantastic for about 4-7 seconds then falls off.. is only better ( pretty much normal runnjing) when priming fuel bulb consistenly.. i believe all is air tight from primer bulb to low pressure fuel pump as when squeezing bulb, i can feel each cycle ( slightly) of the LP pump cycling.. maybe .. maybe not air leak..

- boat is now outta slip and in garage - in case you're interested, here's my to do list now that i can access the motor:

remove intake and all that fun stuff, replace fuel line that goes into low pressure fuel pump, test / swap low pressure fuel pump, remove / clean / reinstall fuel regulator, ohm test fuel line cutoff solenoid ( sits low in motor cowling so possible saltwater residue contamination), reluctantly remove / clean vst ( i have a new hp pump to go in if needed)

- am thinking lp pump as not keeping the vst tank full on it's own without priming at bulb.. wondering as may too possibly be float needle problems as maybe only opens that vst inlet when more fuel is pushed in when priming


going to cut back battery leads as well about 4" in case of oxidation creating too much resistance under load.. a bit skeptical about that as runs better with primer bulb squeezing but of course this should be regular maintenance anyhow when on salt..


Thanks again for all the inputs here - I know i kinda ramble sometimes but wanted to be thorough with my posts and providing an update here as to work in progress in case lessons learned by lurkers as this moves along

- will be in touch soon .. most likely 3-4 days of wrenching in between work / family life
Click to expand...

1. Have you pulled the spark plugs to inspect them yet? Not only if one is broken, you should be able to tell if a particular cylinder is giving you problems.

2. Start with the easy stuff first. Don't go pulling the intake just to pull it. Start with spark plugs and visual inspection of coil packs. Then pull and clean VST. Even though I don't think it's fuel, pumping the bulb does make a change in symptoms. It.may be my idea of bucking and yours is slightly different.

I think you're going to find that it's something simple, like plugs or vst. These engines basically are bulletproof except corrosion
 
After you do 1 vst cleaning, you'll find u can do it in about 20 minutes from removal to installation. They are very easy and very simplistic
 
gotcha codycat.. thank alot for quick input.. just pulled plugs and compressions tested..

ranged between 160 and 200 between all 6..

here's the plug on the lowest cylinder reading.. in all honesty, it looks perfect as light tan brown - identical to all other 5 plugs..
also... battery went down to 10.8v when turning over... concerning as i know these hondas just run on the battery as opposed to alternator powering everything when running..

now mind's a little bit thinking about possible weak spark due to 10.8V as to bucking problem ( to clarify, bucking in my books is absolutely clean running then instantly down to about 1000 rpm as per my DR Honda graph above.. just like if a guy was to remove, then quickly reinstall kill switch 'key' - these types of symptoms seeeeemm electrical in nature to me but so puzzling as runs so much better when priming bulb consistenly when bucking and it smooths right out.. maybe a combination of issues)..
 

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BiglarinVancouver said:
gotcha codycat.. thank alot for quick input.. just pulled plugs and compressions tested..

ranged between 160 and 200 between all 6..

here's the plug on the lowest cylinder reading.. in all honesty, it looks perfect as light tan brown - identical to all other 5 plugs..
also... battery went down to 10.8v when turning over... concerning as i know these hondas just run on the battery as opposed to alternator powering everything when running..

now mind's a little bit thinking about possible weak spark due to 10.8V as to bucking problem ( to clarify, bucking in my books is absolutely clean running then instantly down to about 1000 rpm as per my DR Honda graph above.. just like if a guy was to remove, then quickly reinstall kill switch 'key' - these types of symptoms seeeeemm electrical in nature to me but so puzzling as runs so much better when priming bulb consistenly when bucking and it smooths right out.. maybe a combination of issues)..
Click to expand...
10.8 isn't gonna let any engine run good. I would investigate that further
 
Got vst out last night. Haven’t opened it up yet as need to wait for hp pump plastic holder piece - being delivered tmrw. Then dig into it further.
Thx for the checking in. Appreciate it.
 
High Pressure Fuel Pump Screen was 80-90% blocked within VST.. runs like Big Daddy Don Garlitz rippin down the strip now...
thanks alot for all of the input and recommendations..
i changed all the fuel lines from fuel tank outlet to primer bulb, into motor, internally under cowling into water fuel separator, to low press fuel filter, to low press fuel pump, into VST.
i wish i'd taken pics showing the bottom HP pump screen but was almost like small rubber 'powder' sized pieces had caked onto screen.. obviously due to old fuel lines disintegration.. tricky as got by all the religous maintnenance of all on motor fuel filters in addition to Racor annually and none looked that bad / no suction of hp filter ever..
lesson learned here for me is from now on, will always drain ALL fuel outta line at end of season.. get em all nice and dry internally by evaporation.. disconnecting and draining from racor to high pressure filter purge bolt.. and leave it all opened up during off season..
thanks again all, was pretty much trying most other alternatives prior to tearing into vst.. about a day's worth of solid work - all in.. removal, cleaning , replacing..

Happy Boating
 
BiglarinVancouver said:
High Pressure Fuel Pump Screen was 80-90% blocked within VST.. runs like Big Daddy Don Garlitz rippin down the strip now...
thanks alot for all of the input and recommendations..
i changed all the fuel lines from fuel tank outlet to primer bulb, into motor, internally under cowling into water fuel separator, to low press fuel filter, to low press fuel pump, into VST.
i wish i'd taken pics showing the bottom HP pump screen but was almost like small rubber 'powder' sized pieces had caked onto screen.. obviously due to old fuel lines disintegration.. tricky as got by all the religous maintnenance of all on motor fuel filters in addition to Racor annually and none looked that bad / no suction of hp filter ever..
lesson learned here for me is from now on, will always drain ALL fuel outta line at end of season.. get em all nice and dry internally by evaporation.. disconnecting and draining from racor to high pressure filter purge bolt.. and leave it all opened up during off season..
thanks again all, was pretty much trying most other alternatives prior to tearing into vst.. about a day's worth of solid work - all in.. removal, cleaning , replacing..

Happy Boating
Click to expand...
Glad u got it!


This was my screen
 

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Geez hey - i can't recall but do you run a Racor as well? how long since it had previously been cleaned?

get's tricky when one religously does the on onboard filters annually, and with no definitive breakdown / contamination and still vst screen gets plugged up.. vst is not a desirable job as we know but pretty much becomes a planned maintenance procedure - as in every ~150 hours or therabouts... and then when a guy is in there anyhow, the thoughts of just swapping in another HP pump anyhow becomes somewhat logical.. maybe every few cleanings.. dunno ..

fuel lines should also be every so many years too, my error as this wasn't on my regular replacement scheduling.. as we all know, many run pre ethanol systems and we all know it's detriments to our equipment.. clearly I'm just whining now..
 
BiglarinVancouver said:
Geez hey - i can't recall but do you run a Racor as well? how long since it had previously been cleaned?

get's tricky when one religously does the on onboard filters annually, and with no definitive breakdown / contamination and still vst screen gets plugged up.. vst is not a desirable job as we know but pretty much becomes a planned maintenance procedure - as in every ~150 hours or therabouts... and then when a guy is in there anyhow, the thoughts of just swapping in another HP pump anyhow becomes somewhat logical.. maybe every few cleanings.. dunno ..

fuel lines should also be every so many years too, my error as this wasn't on my regular replacement scheduling.. as we all know, many run pre ethanol systems and we all know it's detriments to our equipment.. clearly I'm just whining now..
Click to expand...
These were new to me engines, so I have no idea on when it was last done. That one was my port engine, the starboard was much better. I attribute it to fuel lines breaking down on a 25 yr old boat.

Yes I do have racors

I have replaced every single item on my fuel system, including new fuel tanks, so I expect not to have to clean my vst any time soon. I only run non ethonal as well.
 
I have the issue of my 225 starts instantly, idles fine . When I get to about 2000 rpm it fall on its face. Doesn’t die but goes back to idling. Took the vst out checked EVERYTHING. The only thing I could find is the hp fuel filter was collapsed. Fuel lines replaced, racor replaced. Haven’t had it out to test. My question is , does anyone think that the hp filter could be the only issue? Also after replacing the filter I started it in a drum of water and took it to 3000 rpm and no issues. But of course under no load.
Thanks for anyone’s input
 
BiflarinVancouver - glad you found the problem. In my initial reply I advised checking that screen on the fuel pump holder. You certainly are not the first 225 owner to have that problem. What I can figure out is how that junk gets through the upstream filters.

Garygin - yes, a collapsed HP filter will greatly degrade performance. So, check it out after replacement. If still a performance issue, read post #2 on this thread.
 
Garygin said:
I have the issue of my 225 starts instantly, idles fine . When I get to about 2000 rpm it fall on its face. Doesn’t die but goes back to idling. Took the vst out checked EVERYTHING. The only thing I could find is the hp fuel filter was collapsed. Fuel lines replaced, racor replaced. Haven’t had it out to test. My question is , does anyone think that the hp filter could be the only issue? Also after replacing the filter I started it in a drum of water and took it to 3000 rpm and no issues. But of course under no load.
Thanks for anyone’s input
Click to expand...
I think I fixed this issue on my post. https://www.marineengine.com/boat-f...-get-on-plane-but-start-right-back-up.480332/
 
I didn't read all the posts in here to see if your issues was fixed or not, but on my BF225 2006 model year, I had fuel issue and I think I fixed it by not using the anti siphon valve anymore. I posted my thread on the link above. Give it a try.
 
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