Honda 150 Outboard Issues

New to the forum and hoping someone can help me. I own a Honda 150 outboard (2008) which I have never had issues with and have maintenance done religiously. During my last service my tech did my usual service as well as a recall with my thermostats. Apparently, they were not opening and closing correctly when engine was hot and cold. Tech checked my plugs and he said they looked fine and didn't need to be changed yet. My engine has approx. 350 hrs on it. So, I go to take the boat out the other day. It's starts up first crank as always and nothing seems wrong. Run it at no wake speed for about 30 mins as I make my way to the intracoastal. I decide before we head to the island to relax and have a few cold ones, I want to go run the engine with some throttle. I start to throttle up and just as I am about to get on plane the engine starts hesitating and the rpm's are revving up and down. Come back down to idle speed and everything is normal. Go to throttle up again and it happens again. The check engine light never came on and I can't visually see any issues with the cowling off. I take the boat back to the lift as it runs at idle speeds with no issues whatsoever. I talk to my father in law who is pretty boat savvy. We decide to pull the fuel water separator in my bilge area and dump it into a glass jar. Fuel is clear and no water in it at all. As more precaution, we change out the fuel filter on the engine (not the high pressure one, I had that changed by tech a year ago) and also check fuel water separator on engine (no issues with it). I dumped sea foam into the tank as I was thinking maybe the gas was "bad" and took it out today. Boat starts up fast as usual and run idle out to intracoastal. Throttle down and boat gets up on plane with ease and run it at about 4000 rpm's with no issues. I am thinking maybe all is solved. Wrong. Come back around and decide I want to try and run full throttle. As I get up on plane again with no issues I get up to around 5000 rpm's and the issue starts again. Engine starts hesitating and rpm's start jumping. It almost feels as if the engine is fuel starved. Both times I ran for about a quarter to half mile before issue started. Does anyone have any suggestions? Sorry this is so long. I was going to siphon fuel out and get fresh in the tank and change the plugs before I throw in the towel and bring it in to a mechanic. Thanks everyone.

Squeeze the fuel bulb when the problem happens and see if that clears it up. It so, you have a fuel delivery problem. Could be pinched or collapsed hose, bad fuel bulb, loose fitting....anything between the tank and the engine. Engine could also be sucking air through a bad o ring on the water separator or fuel filter on the engine.

Also, make sure your plugs are NGK's and not Denso's. They can look good, but be intermittent

Mike.

hondadude is the "go to guy" here so I'd pay attention to what he has to say. I just wanted to add that if you continue having problems, you might want to try running the engine from a smaller, remote tank to troubleshoot instead of the "fuel dump" you are planning. This sounds very much like a fuel supply problem to me too, so I think you are on the right track.
Good luck.

Thanks Mike....I'm going to run it today. I'll check the fuel bulb when it happens and let you know. How difficult is it to change out the fuel lines and do you have a suggestion on where to get new ones? Mike

Thanks JGMO...I'll give the bulb a shot first as the first time it happened I could have sworn I went to squeeze it and it was soft...no fuel in it. I have my fingers crossed that it is a collapsed line rather than a $1000 fix at the mechanic. Mike

Checked all the fuel lines yesterday and they looked good as well as the fuel bulb. Any idea on how to get to the spark plugs?

How did you check the fuel lines to determine that they were good?

Chris, I gave all of the fuel lines a visual check for any cracks and holes. Then squeezed them in various places to see if they were soft in any areas where it could be a compressed line issue. Lastly I checked all the clamped ends and all seemed ok. My father in law is pretty boat repair savvy so he gave them a once over as well and didn't see anything alarming. Checked the fuel bulb and it is working as well.

The easiest way to eliminate any questions on the fuel supply is to connect a portable tank and line to the engine and run it. It ist solves the problem, then the hunt is on for the bad section of fuel feed.

Does the engine sound like it is missing? If so, maybe the plugs do need to be changed. Just because they look ok, it does not mean that they are good. Just had a 135 (same basic engine as the 150), the was missing on two cylinders. Plugs all looked good. They were Denso plugs (not good). Changed them to NGK and it ran smooth as a baby's butt.

Two other things come to mind....

Where did the mechanic touch it? If he checked the spark plugs, he may not have completely connected the connectors to one or more of the spark coils. The #3 coil connector is somewhat hidden behind the cowling and is tricky to connect the connector. So make sure all of the connectors are tight going into the spark coils.

The other thing that it could be is the neutral safety switch. You mentioned that the motor varied in rpms. If the ECM thinks you are still in neutral, when you get somewhere in the 3000 rpm range, the engine will act like it is hitting the rev limiter. There is no easy way for you to tell for sure what the ECM is thinking without Dr H or and HDS, but you can at least eyeball the neutral safety switch, on the front of the engine and make sure it is being actuated.

Mike

wondering if you ever figured this out?

Hello I have a 2008 150 v-tec there is a very important part of maintenance we all over look the high speed fuel filter and the screen under the pump! I had the same problems after many talks on this great forum that is the major fix its
not everything but a big thing a lot of us over look!
Sincerely
greg

grmaro,

I believe you meant to say high PRESSURE fuel filter....but it's a small oversight and I LOVE your enthusiasm!

Thanks for that as you are most undoubtedly CORRECT.

It is BURIED in there and not everyone relishes the idea of going in and taking care of it. But IT MUST BE DONE! I don't think it can be said enough that these don't get the service that they probably should.

jimmyd

I'm bad your right its become a regular do to clean that screen and its under the high speed fuel pump just getting ahead of myself the high pressure filter gets change first and I like to clean e VST Tank a he same time.

Greg