I have a 1993 Johnson outboard that has been giving me problems. When I go out for a troll and give it full throttle (12mph)to get where I'm going, all of a sudden it bogs down and only goes 5 mph. It only goes 5mph for about 10 minutes(still at full throttle)and then it kicks in at resumes at the normal 12mph speed. Then I troll and it's all set until I go out again the next day. Then it happens all over again. Marina suggested it may be a plug problem. I put new ones in and it didn't make a difference. The marina is backed up three weeks. Does anyone know what this could be? I can't wait three weeks. Fishings getting good. I was hoping someone may be able to tell me what the problem may be so I could possibly fix it myself if it's a minor thing. JoeG

have you checked your fuel line and filters for leaks or cleaning? Sometimes they'll idle fine but when you ramp it up a joint or crack sucking air will show up. Had that problem once and it was a crack in the fuel screen housing at the motor. Not that familiar with your motor

one thing I would try is when you give it full throttle try pumping the fuel line ball. See if that makes a difference. Let me know how you make out. One other thing you can try is buy a can of Tune up. Spray it in your carb while it is running and it sometimes will clean out the build up. what are you using for a gas tank? check out these things and let me know and then we can try out something else.

Ryan

Is the product actually called "Tune Up?" Pumping the ball has no effect. Tried that. I use a 6 gallon tank and it was bought new last year.

Ryan,

I'll be up on Thurs evening. You had mentioned earlier last month about wanting to fish Ossipee. Fri-Sun at the crack of dawn I'll be going out. I usually quit by 10am or a little later if they're hitting. Would you like to go? Last time out I got a few good fish in the 18-20 inch range. Joe

i had that problem twice this year, first time it turned out to be a gas tank vent line getting pinched. second time was the gass line under the cowling, it was soft, maybe from the ethynol gas that ive been using for the last couple years. when you gave it gas you could see the gas spraying with the cowling off were a split developed. have the new line, but got the old one working with some superglue until i get the boat out of the water.

I can think of 4 things, in no particular order
1. Water in fuel
2. Punky fuel line
3. Plugged vent
4. Plugged filter
Throbbin Rods

Joe; if it turns out not to be a fuel problem, it most likely is a bad coil or power pack. Check the spark when it,s acting up. Also check wires. Good Luck Cal P.

It's definitely not the fuel or the fuel line. The vent is fine also. I'm not an engine man by any means. How do I check the spark? Explain about the coil or power pack if you would please.

Sounds to me like you are intermittently running on one cylinder you can tell which one by looking at the plugs right after it has the problem. The oily wet plug will be the one thats not fireing. If it is not a fouled plug that is cuasing this I would check the plug wire itself it could be chaffed or shorting out somewhere or possiblly the coil for that cylinder. the electronic ignition power packs for those engine uasuly do not intermitenly fail the ethier work and the engine runs or they don't. As far as other fuel problems i think Trobbin Rods cover them all with the possible exception of a pin hole in the fuel pump diafram but i think that would give you a flat fuel line priming ball too. You might consider buying a Clymer manual for you model and year motor also that will explain alot of stuff and if you are planning on keeping that motor it's a good investment. I have one for all my motors.
also
iboats.com repair forums on teh net is a very good source for reapir infro

Good luck

Glen

That's what I was told. So I changed the plugs and nothing has changed. Could I have blown a new plug right after I put it in? If so, what should I do?

Joe: To check spark,get a tester at a auto parts store,Napa, Robbins etc.Only a couple bucks.Take plug wire off a plug and insert one end of tester into it.Put other end of tester onto spark plug.Tester has a clear part that will flash every time spark goes from coil to plug.Motor will run with tester,just be sure it,s either in the water or on a hose.If all plugs are getting good spark,take plugs out and check for worn electrodes or fouling.I,m not a mechanic either,but hope this helps ya. Cal P.

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It's definitely not the fuel or the fuel line. The vent is fine also. I'm not an engine man by any means. How do I check the spark? Explain about the coil or power pack if you would please.

The plug problem is with the wires. When you throtle up the current goes out to ground. Slower speeds are less current and it runs fine. Put it on a hose and run it after dark in your back yard. You'll see blue sparks on the wire, change that one.