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88 hp johnson won't excelerate under load

J

jbmush

New member
Motor is a 1996 Johnson sp. 88hp. It runs on hose but under load on the lake when I throttle up it just bogs down and if I continue to give it gas it will die. It will only run about 5mph. Compression is good on all cylinders. Any help or suggestions as what might be wrong?
 
Compression is good? How good is it?

With the s/plugs removed, do you have spark that will jump a 7/16" gap on all cylinders with a strong blue lightning like flame... a real SNAP?

If the two areas above are as they should be, the problem is usually fouled carburetors, in which case, remove, clean, and rebuild them as needed.
 
joereeves said:
Compression is good? How good is it?

With the s/plugs removed, do you have spark that will jump a 7/16" gap on all cylinders with a strong blue lightning like flame... a real SNAP?

If the two areas above are as they should be, the problem is usually fouled carburetors, in which case, remove, clean, and rebuild them as needed.

the compression is 110 on 3 and 112 on one. Spark is strong. would fouled crabs be the problem if it runs good with hose but not under load
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the compression is 110 on 3 and 112 on one. Spark is strong. would fouled crabs be the problem if it runs good with hose but not under load
 
the compression is 110 on 3 and 112 on one. Spark is strong. would fouled crabs be the problem if it runs good with hose but not under load
 
On a flushette, many engines sound okay to the untrained ear (no offense intended) but they are not. As far as opening the throttle while on a flushette.... that is a no no as you are inviting a runaway engine and by the time you figure out how to shut it down, connecting rods will be flying out the sides of the crankcase!

The compression is okay, closer than most.

Yes, if it were me, I'd be removing the carburetors, then cleaning and rebuilding them. Pay particular attention to the brass high speed jets (4 total) that lay horizontal in the bottom center portion of the float chamber... way in back of the float chamber drain screw plugs. Clean them manually (carefully) with a piece of single strand steel wire as solvent just doesn't do that job properly.
 
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