Honda BF150 no power

My 2008 BF150 25” ran great until the last time on the water. Halfway through the day it will not rev pass 2000 rpm. Got home and changed the following:

-new Quicksilver bulb and external fuel lines
-new low and high pressure fuel filters
-new mid shaft bushing
-took apart and inspected vst - was super clean
-cleaned the filter above the vst
-spark plugs look great

Took it out today and still will not rev over 2000 rpm under load. With it in neutral it will rev all the way to 6000 rpm and hold it as long as you leave it there. With the prop halfway out of the water, it will rev all the way to 6000, smooth and strong. Under load, it just poops out and will not rev over 2000 rpm.

I’m stumped. It starts right up, idles smooth, shifts smooth, goes in forward and reverse smooth, and will putt around all day without issue at the limited 2000 rpms. Receiving good fuel all the way up the vst and high pressure fuel filter.

The only things left I can think of:

-high pressure fuel pump
-compression check (if this the issue, will it still idle smooth and rev to 6000 strong and smooth without load?)

Hoping to receive some good troubleshooting from the more skilled and experienced folks from this forum, which has taught me a lot so far. Thanks in advance.

What kind of boat do you have? Are you sure it hasn't taken water?It sounds like this motor is just working very hard. It's hard to assist without actually trying it to see what is actually happening.Another thing to check, make sure the prop hub hasn't slipped causing binding with the gearcase under load

I have a 20’ Jetcraft. For sure it’s not taking on water. Bone dry when you remove the plug after being on the water. Hub is pretty much new; and I have tried two different props now with the same result.

Update:

Forgot to mention there are no alarms or overheating. Got a chance to do a compression test today. Tested several times and rounded to the nearest 5, and to the best of my ability. Cylinders from top down:

Cylinder 1: 200
Cylinder 2: 205
Cylinder 3: 195
Cylinder 4: 200

Compression looks pretty good to me. Have a high pressure fuel pump on the way. Took the vst apart. I can see the fuel pump but it won’t budge. What is the easiest way to get it out? It seems pretty stuck in there and don’t want to break anything.

Prise the pump out with two big screwdrivers, it's held in by a rubber grommet. Have you done a fuel pressure test before chucking parts at it, it's unusual for those pumps to do anything other than fail completely.

Double checked throttle linkage; throttle body opens fully. No intake blockage. I noticed there is a valve assembly that sits on top of the intake manifold. It has a lever, when pushed you can see the valve open and close. What does that control?

Haven’t done a fuel pump pressure test. I figured if I have to buy a pressure gauge then might as well just use the funds for the new pump.

How is the fuel pump pressure test performed? Have read threads on people doing the pressure test but none on how to do it.

The valve you mention is called an IAB , idle air byass, this is operated by idle vacuum and reditects the intake from a short to long tract to enhance performance. The fuel pressure is measure by removing the 12mm head bolt on the high pressure filter cover where you install a quick connect fitting for the gauge.

I’m going to check high fuel pump pressure and valve clearance next. I’ve read high fuel pump pressure should be between 40-47 psi.

Does anyone know the intake & exhaust valve clearance?

Inlet 009" inches
Ex 012"

Also check that the throttle valve is fully open at full throttle. Are you sure there is no misfire off idle, there has to be a simple explanation for only achieving 2000rpm, does the engine sound like it is just running at half throttle or is it under extreme load? Just check your throttle linkages, from what you have described, this engine is very healthy mechanically.

One more question, sorry, I am thinking as we go. How many hours has it done, because these motors are known for the cam timing to jump a tooth or two when the chain stretches excessively, usually around 1500hrs when the chain should be replaced?

The throttle body valve opens fully and there’s no blackage. Not sure of hours but supposed to be low. The engine starts and idles great, no misfires, or hesitation at idle or when revved under load to 2000rpm. To me the engine is mechanically as sounds as can be. It just feels electronically limited from revving past 2000. I’m wanting to reset the ecm. Is the procedure to shunt the wires the same as I’ve read on the 200’s and 225’s.

ECU reset has no effect on performance,all it does is cancel any fault history.Best option is to use a dealer who can check everything quickly and properly using the necessary tools and diagnostic equipment. That is the only way to properly check the EFI system for correct operation.You cannot guess sensor values, you could have a faulty TPS or MAP sensor for an example and you wouldn't know.

iang6766 - thanks for all your replies and help in troubleshooting my ordeal. I appreciate it.

I shunted the lime green/black wire and read the flashes. It seems I have two codes... (L = long flash, S = short short). There's a distinct pause between these codes.

First: L, L, S, S, S, S

Second: L, L, S, S, S, S, S, S, S

If anyone knows what these are, please let me know.

Codes 24 and 27, 24 is temp sensor 2 and 27 is faulty temp sensor 4. These two temp sensors are the ones on top of the motor under the thermostat housing, they are fed by a common harness, so look at the connections and check for wire damage or corrosion

Just an after thought, try clearing those codes and run the engine again, they are probably old faults from when the ignition may have been turned on with them disconnected because if they were current you would definitely have either a check engine or overheat light with an alarm.

Thanks iang. I think I actually caused those two alarms when I first got the motor. I had everything rigged up and while the engine was running, I disconnected them to see what would happen. I used it as is up until it started bogging down. I also installed an inline external water temp gauge after the thermostat housing to keep tabs on water temp, which hovers around 124 and has never gone over 130.

I did clear the codes manually per Hondadude and Chawk man's instructions. After letting the motor run for 30 minutes, no more codes when I checked. I did install the new high pressure fuel pump and adjusted the valves, which were a tad tight. She still fires right up and runs great. If time allows, I'll give it a test run test weekend.

Alright fellas. I'm still troubleshooting this no power issue and I think I have it narrowed down. Since my last post, I've installed a new high pressure fuel pump which helped some (it now revs up to 3000 rpm vs 2000 rpm before). Fuel pressure is now at 46 psi but the no power is still present. I did some more googling and I came upon this thread:

https://www.thehulltruth.com/boating-forum/860957-motor-will-not-go-past-4000-rpm.html

I decided to unplug each coil one by one as the motor is running to test and see if the coils are stilling working. When coils 1 (top position) and 4 (lowest position) are unplug the motors sputters and dies. When coils 2 and 3 (middle ones) are unplugged the engine keeps running as normal.

Hope this isn't too confusing: To further test to see if coils 2 and 3 are bad, I moved them to the #1 and #4 spot while moving coils in 1 and 4 into 2 and 3. With this setup and the engine running, the engine sputters and dies when 1 and 4 are unplugged. Unplugging 2 and 3 ended with the same result of the engine still running as normal. This shows that all four coils are working as they should. So basically the motor has been running with only two cylinders firing. What causes the coils to not receive electricity?

In reading the thread link above (post #3), the next culprit is the trigger assembly inside the flywheel. I've tried to locate the part location and the part number without success. Does anyone know where it is located and what the part # is? Also, how involved is it to replace this part?

Thank you in advance.

These motors do not have trigger coils, they use a crank angle sensor. in conjunction with a cam position sensor , ecm distributes spark. Have you checked spark? Usually if one sparks they all spark. Have you done a compression test? Also check that the fuel injectors are all working properly, you can do this holding each one with the engine running to feel if they are pulsing. Just because 2 and 3 aren't firing doesn't mean there's no spark. What do the spark plugs look like, are they all the same? You could have water getting in some how. As you can see, identifying which cylinders are playing up is just the beginning of a thorough diagnosis

Alright gents. I wanted to provide an update to this thread for anyone who might be having the same issue.

First off, my many thanks and appreciation to iang6766 for his help in troubleshooting this with me.

Last time, I was stuck at either coils or fuel injectors. With the advice of iang6766, I tested the coils again and found them all to be sparking. Next, I removed all the injectors and tested those. BINGO! Injectors #2 and #3 were partially clogged. #1 and #4 sprayed nicely as it should. I propped them up and soaked all of them in sea foam for a few hours while I watched youtube on how to clean them. After soaking, I pulsed them and cleaned them all with fuel injector cleaner until they all sprayed the same fine mist. Allowed them to dry and re-installed.

Needless to say that was about a month ago and I finally was able to get it out this past weekend for a trial. She idled so much more smooth and quiet. After some putting around at 3k, I opened her up and she soared to 6k easily pushing the boat to about 40 mph on the gps. Did a little fishing and cruising around for about 5 hrs with no hiccups. I am just elated!

Good job, thanks for the feedback