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1990 Johnson 100 carb problem

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Kth0912

New member
Hello

I am new to the forum and fairly new to diagnosing outboard problems so please let me know if this topic has been covered in another thread.

While on the water recently my motor seemed sluggish on the whole shot...didn't want to jump up on plane. This 100 horse johnson is on a 17' MayCraft so this shouldn't be the case.

So i went home and hooked up the muffs and pulled the air intake off so to spray some carb cleaner to try and clear jets. When I sprayed the cleaner into the top carb, the motor bogged down briefly as usual. But when I sprayed into the lower carb there was no change in the engine. I assume this means blocked jets?

Also, it appears that fuel was being spit out of a needle on top of the carb (bleed valve possibly) and was draining out of the bottom of the motor and down the shaft cowling.

Should a rebuild fix this issue?

Thank you for any help
 
Check the high speed jets in the bottom of the float bowls in the lower carb. You can clean them out with a fine wire.
 
Spraying nay kind of cleaner into the craburetor throats just goes straight through the throats but does nothing for the carburetor.
 
Kth0912 said:
1990 100hp Johnson... On the water recently my motor was sluggish on the hole shot and didn't want to jump up on plane.

1 - I sprayed carburetor cleaner into the top carburetor, the motor bogged down briefly as usual. But when I sprayed into the lower carburetor there was no change in the engine.

2 - Also, it appears that fuel was being spit out of a needle on top of the carburetor (bleed valve possibly?).

Thank you for any help
Click to expand...

I edited your post here fro my own convenience, meaning no offense and hope you don't mind.

1 - The "no change" when you sprayed cleaner into the bottom cylinder indicates that the bottom cylinder is not firing for some reason.... no spark?, no compression?

Remove "all" spark plugs. Check the compression. What are the compression psi readings of the individual cylinders?

With the spark plugs still removed, rig a spark tester so that a test gap of 7/16" exists for the spark to jump. The spark should jump that 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it?
********************

The following is not likely as you sprayed carburetor cleaner into the bottom carburetor and received no response, HOWEVER I am listing it here "Just In Case".

If you have proper compression and spark, your problem in all probability is due to a clogged carburetor. In which case, remove, clean, and rebuild both the carburetors as needed. Carefully clean the high speed jets that are located horizontally in the bottom center of the float chamber, way in back of the drain screw plug.

Let us know what you find.
 
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