New plugs, new fuel , and double seafoam is what I would try first.

So it started great off the trailer; ran great for ten minutes. Then proceeded to bog down/limp after motor off and trolling for a while?
Does it fire right up after trolling for a while or no? If it ever has problems firing up; I’d replace the solenoid and starting motor.

I replaced the solenoid and starting motor on mine a year ago after a starting issue……doesn’t hardly ever bog down or limp anymore now either. I suspect; getting a really good initial start gets the motor running in ideal conditions….which then collaterally/subsequently has it getting on plane better and running better without sluggishness or bogging down.

If you had a fresh 36 gallons in there it’s starting to sound more like an electrical issue= spark plug coils/ HT leads……possibly the ECM. Starting motor and solenoid.

^^^^all those items are cheap (except the ECM) and should be replaced every ten years anyway (except the ECM).

Try replacing the cheapest and easiest to replace first. Put in a new starting solenoid ($15) and starting motor ($60) and see what happens.

Then Spark plug coils/HT leads.

It sounds like you’re going into guardian mode but you should be getting an alarm.

Does it have a primer bulb?

It starts easy and runs fine off the trailer. Run 10 minutes somewhere and fish for an hour or so and it usually won't restart. If it does restart, it dies trying to get on plane and then will not restart. Two hours later it will start and run fine like nothing happened just like it did off the trailer.

has a brand new OEM primer bulb.

Originally Posted by Mark C
New plugs, 36 gallons of super unleaded and a can of Seafoam didn't fix it. Doing the same thing. I'm going to try and do what GarySHO is suggesting this weekend.

Looks like you've pretty well covered fuel issues. Time to dive into sparkalators and such.

lol, this is exactly the scenario the way mine started out. I had to get on the trolling motor a couple times to get back to the ramp, put it on the trailer and the sob would start right up before I left the parking lot. Put it back in the water and start the process all over again. Absolutely maddening. I’ve had two different shops throwing parts at it, now it starts just fine every time but goes into guardian after the first run of the day, everyday. Oh, and no, it won’t do it on the muffs, which is just wonderful trying to diagnose something. The only upside is i have another boat, I use this pos to keep hours off of my other one. That’s not working out so well right now lol.

We have a Yamaha 150 that would send out the low oil alarm and go into limp mode. Replaced the oil pump, no dice. Traced circuitry and finally figured it out. The safety trim switch on the motor was stuck. It was just a little thing located on the transom bracket. When we'd raise the motor, the switch would stick when you lowered it back down. Lubed it up and worked fine after that.

Boat motors and boat electronics are fascinating. Such simple designs with so many little potential gremlins.

Bump to get an update when you find the problem!