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2008 Honda BF150 Power Loss

J

JD4WD

New member
Good afternoon folks,

I'm posting for my Dad who owns a 2008 Honda BF150 and has been troubleshooting and replacing parts on it for the past few months. He asked if I could help do some research and I figured this was the best place to ask!

He was able to water test it yesterday and experienced the following:

- Able to get up to 3800 rpms and that is when the engine starts losing power
- Does not stall completely
- If he stays on throttle it will surge/lose power
- When he backs off the throttle, the engine recovers and he's able to jump back on plane but issue persists at around 3800 rpms

He has replaced spark plugs, fuel lines, low pressure pump, fuel filters, water separators, spool valve, and MAP sensor. He thoroughly cleaned out the VST as well.

Any ideas or advice on what we should target next? Thanks!
 
I know you mentioned fuel lines—does that include the bulb? It may be worth it to see what is happening with the bulb at that rpm. Is there a racor setup as well?
 
Try with a different portable (dinghy) fuel tank. If problem persists, start working your way up from the LP Fuel Filter. Not sure if the BF150 has an IAB. If it does, the IAB actuates at 3950RPM and can cause surging. Also check fuel line entering engine at grommet point, is known to crush and cause fuel starvation... could also be air leaking into the fuel system... Boat fuel tank intake restrainer could also be dirty or obstructed. Also can check VST float and needle (if applicable to the BF150).

If working your way upwards from engine fuel entry point grommet and LP fuel filter, not sure about the BF150, but the BF200 has 5 fuel filters: LP filter, HP filter, Mesh, Insulator & Pump Fuel Filter, and you may also have an external fuel/water separator which could also be the culprit.

Start with the easy stuff and then step by step.
 
This is clearly a fuel supply issue, as suggested, try another fuel supply. A fairly common problem is where the fuel line passes through the righing grommet, it can eadily get pinched closed, run a fuel line from a caddy tank straight onto the fuel filter under the cowl and see if that solves the problem. If it does, then your fuel line is the issue.
 
Since you mentioned surging try cleaning 02 sensor, easy to take off 22mm or harbor freight 02 socket , clean with carbon remover spray mercury power tune spray or marvel mystry oil and use brass brush to knock off carbon on the outside, a steel brush can damage outer coating.
 
Ok, can you tell us if it is just at 3800rpm? Or can it go higher? It certainly could be a fuel restriction but it could also be a gear case tightening up from lack of lube, easily ruled out by checking lower unit oil. Might want to do a quick check of that as well.
 
TritonFisher said:
I know you mentioned fuel lines—does that include the bulb? It may be worth it to see what is happening with the bulb at that rpm. Is there a racor setup as well?
Click to expand...

No, he only replaced the lines from the external water separator (Racor) to the engine cowling. He has an order placed for an entire fuel line kit which I believe includes a new bulb. Once we receive the parts and run some additional test I'll report back, thanks!
 
Blacktimes said:
Try with a different portable (dinghy) fuel tank. If problem persists, start working your way up from the LP Fuel Filter. Not sure if the BF150 has an IAB. If it does, the IAB actuates at 3950RPM and can cause surging. Also check fuel line entering engine at grommet point, is known to crush and cause fuel starvation... could also be air leaking into the fuel system... Boat fuel tank intake restrainer could also be dirty or obstructed. Also can check VST float and needle (if applicable to the BF150).

If working your way upwards from engine fuel entry point grommet and LP fuel filter, not sure about the BF150, but the BF200 has 5 fuel filters: LP filter, HP filter, Mesh, Insulator & Pump Fuel Filter, and you may also have an external fuel/water separator which could also be the culprit.

Start with the easy stuff and then step by step.
Click to expand...

Excellent, thank you! I'll share this list with him - We're going to do some troubleshooting this weekend (weather permitting).
 
iang6766 said:
This is clearly a fuel supply issue, as suggested, try another fuel supply. A fairly common problem is where the fuel line passes through the righing grommet, it can eadily get pinched closed, run a fuel line from a caddy tank straight onto the fuel filter under the cowl and see if that solves the problem. If it does, then your fuel line is the issue.
Click to expand...

I agree, it's definitely acting like it's starving for fuel at higher rpms. Forgive my question if it's silly as I'm not as well versed as my dad and all of you - Would a pinched grommet cause the engine to run poorly even at lower rpms?

We'll verify the grommet isn't pinched and try the external tank and let you know how it goes, thanks!
 
HonDan said:
Since you mentioned surging try cleaning 02 sensor, easy to take off 22mm or harbor freight 02 socket , clean with carbon remover spray mercury power tune spray or marvel mystry oil and use brass brush to knock off carbon on the outside, a steel brush can damage outer coating.
Click to expand...

I know he pulled the 02 sensor recently but definitely worth another look. Would there be any visual indicators if it's bad or any way to test that it's failing?
 
Update:

We had a chance to do another water test last weekend and ran into new/different symptoms. The engine still bogs down around 3800 rpm, however, after around 30 minutes into the water test, it started bogging at lower rpms and even sputtered while idling.

Here is the list of work we've done since the last test:

- Cleaned 0/2 sensor
- Changed lower unit oil
- Verified grommet is not pinched
- Replaced bulb and fuel line to the water separator

Troubleshooting steps taken during water test:

- Pumped squeeze ball when engine was surging and the issue persisted
- Tried a portable tank with new/clean fuel and the issue persisted

I also took a quick video of the issue:
https://youtu.be/EvVxN26b_ZE

We have yet to do a pressure test on the HP fuel pump, he doesn't have the necessary equipment yet but that could be our next step.
 
Harbor freight has fuel injection test kit. you connect the tester to check port on the cover of the high pressure filter. if pressure is lower or higher than 40-47psi at idle then check the vacuum tube to the pressure regulator which is on the top of the fuel rail. if that vacuum tube on the pressure regulator has a split in it where it attaches then that might be what's causing the problem. ref 5-103 and 5-106 of service manual. Looking at the video it looks fuel related for how fast it is surging. Could be bad regulator or injector clogged up going bad. if fuel pressure is good at idle and vacuum is good to regulator and you can change pressure by squeezing vacuum tube on regulator and it stays within specs then. look at injector or 02 sensor.
 
Was the priming bulb (ball) hard when squeezing? Does not look like an O2 Sensor to me, have been through many of them (2 a year per engine) and never had those symptoms. At least you know know that it is from the grommet upwards, not fuel tank, fuel line related, good job. I would start with the LP and HP fuel filters, do you know how many hours the engine has and when it was last serviced?
 
Have you looked at the plugs to see if any differences between the colour of them or if any wet? Would an injector issue in 1 cylinder show up there? I’m not a fuel injector guy, most of my work had been on carbed stuff.
 
I put the harbor freight fuel injection test kit on my 150 engine. it has a small brass threaded connection that fits the BF150 fuel test port. You will need to remove mid cowling to get access to it test port 12mm screw on the high pressure filter cover on the vst and be very careful to thread the tester in by hand so no to cross the threads in VST. Once installed and turn the key the fuel pressure will register about 40 PSI, when you start and run the engine it shows steady pressure near 40 psi. if you remove the vacuum line from fuel regulator the pressure went up 5-10 psi but still held steady. Revving the engine up and down didn't change the pressure reading it stayed steady at 40. After shutdown the pressure stayed at 40 psi until disconnected from the connector tube. make sure you put the suction vacuum line back on the regulator or you could damage engine bearings from sucking up debris. hope this info helps for your problem.
 
Blacktimes said:
Was the priming bulb (ball) hard when squeezing? Does not look like an O2 Sensor to me, have been through many of them (2 a year per engine) and never had those symptoms. At least you know know that it is from the grommet upwards, not fuel tank, fuel line related, good job. I would start with the LP and HP fuel filters, do you know how many hours the engine has and when it was last serviced?
Click to expand...

Yes, the bulb was definitely hard when squeezing but did not change the engine sputtering at all. We checked/cleaned the 02 sensor and agree with you, we don't think that's the culprit. It has close to 600 hours and has been serviced, (new plugs, filters, etc.).

We're going to order a injection test kit and run a few more tests. I'll let you know what we find. Thanks!
 
HonDan said:
I put the harbor freight fuel injection test kit on my 150 engine. it has a small brass threaded connection that fits the BF150 fuel test port. You will need to remove mid cowling to get access to it test port 12mm screw on the high pressure filter cover on the vst and be very careful to thread the tester in by hand so no to cross the threads in VST. Once installed and turn the key the fuel pressure will register about 40 PSI, when you start and run the engine it shows steady pressure near 40 psi. if you remove the vacuum line from fuel regulator the pressure went up 5-10 psi but still held steady. Revving the engine up and down didn't change the pressure reading it stayed steady at 40. After shutdown the pressure stayed at 40 psi until disconnected from the connector tube. make sure you put the suction vacuum line back on the regulator or you could damage engine bearings from sucking up debris. hope this info helps for your problem.
Click to expand...

Awesome info, thanks!

Looking at Harbor Freight now, is this the kit that you recommend? https://www.harborfreight.com/autom...n/basic-fuel-injection-service-kit-64939.html

Just out of curiosity, if we get a reading lower than 40 PSI does that indicate a bad HP fuel pump? That's one of the only parts that we have yet to replace.
 
NSDON said:
Have you looked at the plugs to see if any differences between the colour of them or if any wet? Would an injector issue in 1 cylinder show up there? I’m not a fuel injector guy, most of my work had been on carbed stuff.
Click to expand...

Yes, we have inspected the plugs on multiple occasions. There has been no color differences or anything out of the ordinary. We've also replaced all the plugs and wires.
 
No, that is not the same kit I have. The kit I have that comes with the connection tube to VST is Fuel injection Pump Tester item 62623. There is one on ebay now for $20. you can see the VST connection tube in the ad at the top of the picture
 
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