2005 BF 150 intermittent power loss

I’ve been fighting an intermittent problem on my 2005 Honda 150HP outboard and am wondering if anyone has any suggestions.
2005 BF 150, 1,150 hours which I purchased at 100 hours. It’s on an aluminum 2272 SeaRaider.

For three years it has had an intermittent problem where it won’t accelerate past 12-15 mph when the throttle is pushed forward. Usually if the throttle is left around ¾-full open it will eventually accelerate and run normal. Sometimes the normal running will last for hours/days, sometimes it will return the next time I attempt to accelerate. Occasionally at cruising speed it will just slowly decelerate to the sluggish, bogging speed.

Since battling this problem I have generally noticed the issue is most common when the boat is heavily loaded such as 5 adults+gear. When relatively light the problem either doesn’t occur or happens less. I found that adjusting the trim of the motor may help it run normal but this could have been coincidental as well.

I have taken it to my Honda dealer in Wenatchee, WA twice. They check for codes (none), replace the fuel filters, tell me it runs great and when I take it out, the problem comes back. Since they are pretty much a motorcycle shop I then hauled it to Three Rivers marine in Woodinville, WA hoping more outboard experience would help.

They have checked it for codes (none), replaced fuel filters, replaced injectors, cleaned/serviced VST, checked compression and a few other maintenance items based on the number of hours. I went out on a test with the mechanic and it worked great. They could never get it to run poorly. Then the first time I used it after that, the problem returned.

After much research I suspected water in the fuel and did find water in the Racor and separator on the motor. None of the mechanics had had checked or serviced this. I drained, cleaned and dried the tank, replaced the anti siphon valve, replaced Racor, all 3 fuel filters on the motor, fuel line from tank to motor, primer bulb and spark plugs. Looked around the inside of the tank with an inspection camera, nothing remarkable. Running it on a different tank does not solve the issue. The vent line is clear. Low pressure fuel pump is new.

The motor never has trouble starting or idling. If running poorly and the throttle is pulled back to idle it will often die, but not have trouble restarting.

I just did the decarbonization procedure with Seafoam, adjusted valves, oil change and replaced spark plugs. Both mesh screen on the V-tec had metal shavings on them; both replaced.The last time out after that service it had trouble with low end power, then took off and ran normal but after 10 miles at 30 mph it sputtered lost power and the overheat alarm went off then it died. Engine was very hot and smoking; would not turn over. After cooling for several hours, it would start and run but smoked a lot so I shut it down. Impeller and thermostats are new and engine was pissing strong.

The oil seems dirty to me for <1 hour. Pulled plugs, they seem to have a lot of carbon for being new. Looking in at the top of the pistons, they look like the bottom of a dirty coffee pot. I did a compression test and all cylinders are around 170 psi cold. With the batteries charged the motor struggles to turn over even with spark plugs out.

At this point I don't know what to do. I either have to take another crack with a mechanic or replace it. I'm gun shy to invest thousands that might not fix the problem that could otherwise go towards a replacement. I'd appreciate any advice on what's going on and if this is likely worth the investment in chasing a repair or if I should give up.

Thanks!

The book says compression should be 222 -250 psi at wide open throttle. Just be sure you had the throttle wide open when you checked it.

Did the compression change before and after you did the decarb?

It looks like you changed oil after the decarb? Is the correct? If you changed it before, the decarb probably made it dirty.

When you checked the valve clearances......Were the tight or loose?

Also...when you checked the valve clearances.....did you check the timing marks? Any strange noises from the top of the engine? If so, the timing chain tensioner could have lost tension and caused the chain guides to wear and the timing chain could have jumped time. That does not happen a lot.....just a possibility. This could cause the motor to struggle when turning over.

Not knowing your mechanical ability....are you sure you adjusted the valve clearances correctly? Did you use the official Honda shop manual for specs? I have found that the aftermarket manuals do not always have the correct specifications.

Timing could also cause an overheat. You said you changed the thermostat....did you change both (2) thermostats? Do you know that they are different thermostats with different values?

Other that the above, once the compression and overheat issues are figured out.....one other thing to check that could affect the running of the engine.....you could be sucking air. You will need a short piece of clear plastic hose (about 5/16" internal diameter) and a double male nipple and insert the hose between the output of your low pressure filter and the hose to the vapor separator. You will have to run the engine without the cover on and will need a helper to either run the boat while you watch for bubbles in the fuel or you run the boat and the helper watch. You might see a few bubbles at first, but they should quickly go away. If there are going to be bubbles, you will see them when there is a heavy load or you are really pushing the engine.

If you see bubbles, then move the clear hose up, little by little toward the fuel tank. Try next between the engine's water separator and the low pressure filter. If there are still bubbles, move it, before the engine's water separator, etc. I think you get the picture. When the bubble go away, you would have just passed the trouble area.

If you are sucking air, what happens is, little by little, the vapor separator gets less and less fuel for the demand and eventually the vapor separator runs so low on fuel that the high pressure fuel pump can not supply enough fuel to the injectors...causing the motor to slow down and eventually stall, especially, if you keep trying to push it. It has enough fuel to restart and then after restart the engine has low demand and the low pressure fuel pump has enough time to refill the vapor separator and all is back to normal.....until there are more air bubbles.

If no bubbles, then I would try the separated portable tank that you have tried before, but connect it directly to the low pressure filter on the engine....bypassing all the hoses etc before it. There could be a collapsing or partially kinked hose....especially where it goes through the engine grommet. The result would be fuel restriction, with essentially the same outcome as having air bubbles.

There....just a few disjointed thoughts.

Mike

Thank you for the detailed response, Mike. Answers to your questions below.

I have not tested for air leaks, I will do that.

Compression was checked with throttle open. I did not check the compression before the decarb. It was checked several years ago after the problem began by a mechanic. Was 190-170 psi which they said was normal for the age/hours despite the 222-250 in the manual.

Oil was changed after the decarb.

6/8 of the valves were barely tight. I have the factory Honda repair manual and used those tolerances.

The correct thermostats were installed in the correct location using the colors/codes per the manual.

No strange noises out of the top end but I am interested to investigate the timing chain. I'll look in the manual but am interested in any recommendations regarding this procedure.

Thanks!

I’m not saying you have the same issue, but we had a very similar problem on a ‘94 Evinrude. It would run great some days or for an hour, then the next it would not get on plane or take 10 minutes to get on plane. We brought it to several marine mechanics, changed power head, coils, all sorts of stuff. Finally, the last mechanic replaced the CPU and it’s s been great for the last 4 years or so and still running. I don’t know how you can test it, but perhaps someone can run diagnostics on it.

Something I noticed on the timing that I'm wondering if it indicates the timing chain has jumped. When getting the engine at TDC, you align the cut out in the crankshaft pulley with the mark on the chain case, then check the marks on the camshaft sprockets to make sure you are at the top. When the mark on the crankshaft is exactly aligned, the marks on the sprockets do not perfectly align. I attached a photo of the page in the manual that I am talking about. The two marks shown are off by about 3/16". Is this normal or has something gone wrong?

Timing marks are probably ok if they are that close. If I remember correctly,. About the only time that the marks will align exactly is when the timing chain is put on. I made that mistake years ago and removed crank pull and chain housing cover to verify.

It was a good learning experience...but an awful waste of time.

Mike

OK goof to know, thanks Mike.