1985 Johnson 90HP running rough NEED HELP

[mick3446]

This Johnson 90HP model J90TLCOS has been sitting up for a year?I rebuilt the carbs, replaced the fuel lines, vac lines, spark plug wires and spark plugs. The engine starts and runs a little rough but there is a mud like goo that comes out of the prop. Also the engine will hiccup sometimes and stall out. I have checked the compression and the top two cylinders are 119.5psi and the bottom two are 120psi. I have fresh gas 98 octane mixed 50:1. When I rev-up the engine it seems to run ok but it may miss a little and I notice light bluish smoke with an occasional darker color smoke around when it hiccups. If anyone has any Ideas where I need to start please let me know. Thanks for your help

 

[tashasdaddy]

Re: 1985 Johnson 90HP running rough NEED HELP

have you check spark with a tester, on all 4 cylinders? did you do this when you did the carbs? http://forums.iboats.com/showthread.php?t=244013

 

[mick3446]

Re: 1985 Johnson 90HP running rough NEED HELP

Yes?I used your instructions for several of my boat projects. The carbs are clean I have not made any adjustments because I?m not sure if these carbs can be adjusted? As for testing for spark..I used a spark tester and all four cylinders showed sparking. I failed to mention in my previous post that I have a heavy fuel smell after running the motor even the smell gets in my clothes so hours later I can still smell fuel on my shirt.

 

[DJ]

Re: 1985 Johnson 90HP running rough NEED HELP

Describe-"hiccup".

Is it backfiring from the carbs or out the exhaust?

1. Carb=lean.

2. Exhaust=rich or plug wire on wrong plug.

It appears you are running very rich. That is usually a fault with needle/seat and/or float levels.

You may also have a bad diapragm in the fuel pump.

One more thing-are the thermostats in this engine?

 

[Chinewalker]

Re: 1985 Johnson 90HP running rough NEED HELP

Also, might want to get some 87 or 89 octane fuel. Although probably not your issue, 98 octane is way high for a standard service motor. Thought it might be a typo...
- Scott

 

[mick3446]

Re: 1985 Johnson 90HP running rough NEED HELP

DJ,
The Termostats were removed and repalce with dummies ( just the termo cases) and the 98 oct is incorrect I should have said 89 sorry. The hiccup is when the engine is running and there is no real back fire anywhere but it will just stop... not a stall stop...I mean just stop fly wheel stops and almost bounces backwards at the moment of the hiccup. The plug wires are on: top left coil to top left spark plug bottom left coil to bottom left spark plug, top right coil to top right spark plug and botom right coil to bottom right spark plug. Hope this answer your questions and can help me figure out whats wrong thanks for your help.

 

[DJ]

Re: 1985 Johnson 90HP running rough NEED HELP

1. Put REAL thermostats back in. That engine needs them to run right. Otherwise you get hot and cold spots in the cylinders.

2. The "hiccup" sounds pretty violent. I would remove the flywheel to make sure you have not sheared the flywheel key.

3. Have you performed the "link and synch" procedure?

 

[mick3446]

Re: 1985 Johnson 90HP running rough NEED HELP

What is the "link and synch" procedure?

 

[mick3446]

Re: 1985 Johnson 90HP running rough NEED HELP

I am still not sure what a link and sync procedure is but let me fill you in on my new discovery: When the motor is running and I move the motor with the trim it seems to bog down when trim completely down or slightly up. But if I level the motor out is runs at its current best? which still it seems to be missing would this be a float issue? The carbs have be rebuilt and new floats installed.