Intermittent ignition(?) problem

[metriccrescentwrench]

'81 Johnson 90. On rare occasion it will lose power and run rough, but not real rough - it seems to me that it's probably running on 3 cylinders when it's doing this. It only happens for 30 seconds to a minute at a stretch, and not all that often - maybe once in 3 or 4 outings.

I've checked the plug wires, they all look to be in good shape. I don't want to just start throwing money at it in the hopes of eventually getting lucky, but with a problem that's probably not going to show up running on muffs I don't really know where to start.

 

[trexmerc]

Re: Intermittent ignition(?) problem

first thing i would do is check all ground wires

 

[metriccrescentwrench]

Re: Intermittent ignition(?) problem

I won't disagree with that. However I kinda' don't think that's a problem in my case as every spring I go through and snug up everything. But it won't hurt to check.

 

[jonesg]

Re: Intermittent ignition(?) problem

Take a timing light out with you, when it acts up put the light on it and see which side is dropping spark, if both banks have good spark consider the carbs.

 

[metriccrescentwrench]

Re: Intermittent ignition(?) problem

Take a timing light out with you, when it acts up put the light on it and see which side is dropping spark, if both banks have good spark consider the carbs.

Man, that ain't gonna' be easy. I can see it now, my son's riding backwards on his wakeboard and I shut it down. "Dad, what the h#$%???" "Just stay in the water while I hook up the timing light and drive around a little bit."

Oh well, if I can't get this figured out it may come to that.

 

[metriccrescentwrench]

Re: Intermittent ignition(?) problem

Update. I checked all electrical connections, snugged up ground connections, etc.. Engine has been running trouble free the last few times out so figured maybe I got it licked.

Well, today I took my son wakeboarding and it briefly acted up a couple of times. After he'd punished himself enough on the wakeboard we took a ride around the lake. It acted up again, this time to the point that it would only idle. I opened the lid on the fuel compartment and found the primer bulb was collapsed. I thought maybe I'd forgot to open the vent on the gas cap, but that wasn't the case. I switched the fuel connector to my 2nd tank and everything was fine.

Once we got home I pulled the fuel dip tube and that was ok. SO... it appears that the problem the whole time was a flaky quick connect on one portable fuel tank.

 

[jonesg]

Re: Intermittent ignition(?) problem

Why not get a decent used tank off craigslist and plumb direct, those $12 connectors can cause melted pistons. And the bulb should be visible, not inside a compartment.