Mercury two stroke cutting out

[Gregg927]

Originally Posted by David M

What is the color of your spark plugs telling you?

Spark plug color is possibly saying number two is not firing as often; it is relatively shinier than the other three new plugs.

Thanks for your reply.

[hobopacket]

Ok, yeah spun hub. Probably out of the question. I would start looking at the fuel end of things if it were me.

[Gregg927]

Originally Posted by SV Bacchus

It was mentioned previously and dismissed so I'm sure you will dismiss this as well.

I have a 65MP Merc that I converted to premix, as is yours. I also had the same intermittent run good, run sorta OK, run good, run sorta OK. It drove me nuts for about 6 months. I too was SURE it was spark but I didn't know if it was plugs, wires, computer or what.

Oh, forgot to mention it is a pontoon boat and I have two 6 gal red gas tanks on the rear.

One day it hit me like a 2X4 in the head, it was only acting up ON ONE GAS TANK!

I sat it aside, bought a new gas tank and have never had the problem since. It was obviously sucking air after it was 1/4 to 1/3 empty. Yeah, I could have bought a new pickup tube but the tank was nearing the end of it's life expectancy anyway.

Do yourself a favor and get an aux tank from a friend, or whoever, and at least try it before you go spending any more bucks researching the problem.

FWIW..

Oh, I like this idea. I will gizmo something up. Presently she is running on the built-in belly tank, could have a leak somewhere along the way.

Thanks.

[HopCar]

If the boat accelerates when the rpm increases, you're back to a power head problem. Forget what I said about the prop and lower unit. I now like the idea of trying a different fuel supply to see if the problem is there.

[Madehn]

sounds like the classic case of a coil breaking down under the load- they will often do fine until you get into the higher rpm range and then the symptom is exactly like you describe- personally i would change the wires and the coil(s) out-- neither is real expensive-- if that doesnt do it take the boat out with a friend with the cover off the motor and a can of wd40 when the motor starts to flutuate in speed, spray the wd40 around evry hose connection you can find and also around the intake gasket-- if the motor speeds up and stays at the higher speed after spraying one area, you have found your air leak.

[Gregg927]

Originally Posted by Madehn

sounds like the classic case of a coil breaking down under the load- they will often do fine until you get into the higher rpm range and then the symptom is exactly like you describe- personally i would change the wires and the coil(s) out-- neither is real expensive-- if that doesnt do it take the boat out with a friend with the cover off the motor and a can of wd40 when the motor starts to flutuate in speed, spray the wd40 around evry hose connection you can find and also around the intake gasket-- if the motor speeds up and stays at the higher speed after spraying one area, you have found your air leak.

Got it! Thanks for the how to.

[Fiveslide]

Originally Posted by Madehn

if that doesnt do it take the boat out with a friend with the cover off the motor and a can of wd40 when the motor starts to flutuate in speed, spray the wd40 around evry hose connection you can find and also around the intake gasket-- if the motor speeds up and stays at the higher speed after spraying one area, you have found your air leak.

That was going to be my first guess, intake air leak.

Does it seem to be idling a bit higher? In neutral, if you rev it up, does it seem to take longer for the rpms to come back down?

[Gregg927]

Originally Posted by Fiveslide

That was going to be my first guess, intake air leak.

Does it seem to be idling a bit higher? In neutral, if you rev it up, does it seem to take longer for the rpms to come back down?

Don't know about the rpm drop speed Will check it out. Thank you for your reply.

I've been land bound for the last few days, anxious to get back on this task.

[westwinds]

I remember having this problem many years ago where the gap on one of the spark plugs was set too close. It would miss consistently and evenly at light throttle and have normal power at full power setting on throttle. I pulled the plugs and properly redid the gap. Problem solved.

[tuffr2]

I had a 1989 100 HP Mercury labeled as a Searay. That engine always ran like crap unless I used it a lot. On a 9 day vacation using it a lot everyday it started and ran really nice. Then I let it sit for 2 weeks. It was hard to start and keep running. It also ran like crap for the 1st hour. This was the way this engine always was. Had the boat for 15 years. Yes, I could tolerate it...but just barley.

Maybe your engine runs the same way?

My engine was a Mercury labels as Searay and not the old Crysler Force engine labeled as a Mecrcury.

I had a 1985 Bayliner with a super crappy Force engine. I only had that boat 1 year.

[tuffr2]

You get any more info on your engine problem? Solve, half-solved?