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87 Johnson 88 HP SPL has no power under load

J

jerryny

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Ok I am back after hand surgery. Helped son put boat in river. It purrs like a kitten while idling. However as soon as you put it in gear and give it gas the motor just bogs right down like it has no power.

Between the previous owner and him the following has been done

New Power Packs and coils
New plugs and wires
Rebuilt water pump
Replaced head gaskets and cleaned out all water passages
All new gas and filters

Checked spark while running on water and all 4 cylinders looked good
Pumped fuel ball while in gear but it didn't make a difference

All that leaves that he can think of are the carbs. Can the carbs really cause this kind of problem? It revs up fine. It only seems to have no power when in gear and trying to accelerate. Why would it idle fine put have no power under load. What in the carbs could cause this difference?

Plan to rebuild carbs but was wondering if there is anything else that should be looked at.

Thanks
Jerry and eager son
 
Post the results of a compression test.-----Most motors will wind up in nuetral and it is a meaningless test.---Yes when mixed fuel sits in these carburetors for long periods of time it plugs up the jets.------Cleaning of carburetors is an easy job and usually no parts are required.----I call it a " no money fix " and should be done.-----Are all linkages attached on carburetors ?-----Does spark jump an actual gap of 7/16" or better ?----------Have you confirmed that all plug wires are correct, top coil to top cylinder and orange blue to each top cylinder ?
 
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In agreement with "racerone"..............

If compression and spark are as they should be = clogged high speed carburetor jets. Jets are removable/accessible in back of the drain screws of the carburetor float chambers..... 2 to a carburetor, 4 total.
 
Both cold and warm compression tests look good. Was about 135 on all 4 cylinders

I drained all the old fuel about a month ago and filled it up with fresh gas/oil and fuel stabilizer.

Plug and coil wires are correct

Linkages are hooked up. Could see them moving as the throttle was raised.

Will do spark gap test. We ran with 2 inline spark line testers while on the river and they always lit up while running. Frequency of lites increased as the motor was sped up while in gear. Not sure how bright they should be but we were able to see them in the bright sun light.

I have a gap tester now I just some instructions on how to do the test.


Thanks
 
Verified that the spark jumps on all 4 cylinders. I guess that just leaves the carbs as the cause of no power when under load. today.
 
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