johnson 25 1998 Bogs Down WOT

Johnson 25 Electric start runs fine WOT, 6000 RPM for about 5 minutes then bogs down, misses; runs fine at low RPMs. Rebuilt carbs. Any recommendations, i.e., rebuild pump??

Re: johnson 25 1998 Bogs Down WOT

Does pumping the fuel primer bulb cause the problem to cease? If so, suspect either a minor fuel leak between the fuel pump and the fuel supply, a fuel restriction (usually causes the primer bulb to collapse somewhat), or a failing fuel pump.

Re: johnson 25 1998 Bogs Down WOT

What is the model number? If your engine is a triple it could be the powerpack.

Re: johnson 25 1998 Bogs Down WOT

Check your fuel for water in it.

Re: johnson 25 1998 Bogs Down WOT

J25ELECE, new gas tank/new gas. I'll try the bulb squeeze trick to eliminate the fuel pump or if positive, do the rebuild. And bite your tongue, don't even want to think about a power pack issue, I'd rather blame the ethanol gas for making our old reliables run like, well you know. I was hoping someone had experienced the same issue and what their fix was! Understand it could be a myriad of things.... Thanks to all who responded.

Re: johnson 25 1998 Bogs Down WOT

Yes. many of us have experienced that same issue within a 30 year period or so, hence out reply. If pumping the fuel primer bulb doesn't cure the problem.............

Check the compression: What are the psi reading of each individual cylinder?

Check the spark: S/plugs removed, spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it? The gap is important.

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark. Note that checking spark by using the spark plugs is a waste of time.