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Drive issue

B

Blakes

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I have a 1994 Johnson outboard. It runs good until I put it in gear. When I put it in forward or reverse it only goes about 5 mph at full throttle and often bogs down, struggling and dies. But when I go back to neutral and ten the engine it sounds normal. Any suggestions on what the problem may be. It has new and correct lower unit fluid, changed last month's before hitting the water. The problem started last summer.
 
OK what motor would this be 4 hp or 400 hp ?-----But you start with a compression test and check for spark on all cylinders.----Likely nothing to do with the lower gear box at all.
 
Sorry, thought I included that. 90 up. I checked the compression, 90 psi on all 4 pistons. They all seem to be firing, the wires shocked me when I was checking the plugs
 
Test compression with another gauge.----Good spark will jump a gap of 7/16" or more, does it , yes or no.----Did the problem start suddenly, yes or no ?----Have you checked for water in the fuel ?-----All motor run " good " in neutral and that means nothing on an outboard and is no indication of motor condition.
 
90 hp. Autocorrect turned it into "up". I cleaned the carborator, I premix 50:1. The previous owner took the original fuel pump off and replaced it with a regular one instead of a dual.
 
Yes, the problem started suddenly. Last summer we were boating, full throttle and it slowed down to a stop, rpm gauge quit working and hasn't worked since then. I restarted it, and it did fine the rest of the day. It did it a few more times throughout the summer, but worked fine again afterwards. Then I took it out yesterday, it wouldn't get above 5 mph and bogged down, dying again. Thanks for the help, I'll check the plugs and get another gauge to check compressiom
 
Does spark jump an actual 7/16" gap in air , yes or no ?----It is important to answer questions.----Checked for water in the fuel ?
 
I'm not sure. I'll have to check that when I get back home. I'm at work right now. For the most part, the fuel was fresh, i put half a tank with treatment in it before I went to the lake. I didn't check the plugs, except to see if they were sparking
 
The spark plugs are not used to test for strong spark !---The ignition system was engineered / built to be able to jump a gap of 7/16" or more.----That is the test you should do.----Then again spark could be shorting to the cowling so running with the cowling off is also a test you could do.
 
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