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1990 40 hp evinrude

M

Mustanger123

New member
I have owned this from New. The issue I have been experiencing for the last 5 seasons is the engine will run fine and cruise at 18 mph and all of a sudden will drop down about 3-5 mph and will not let me raise the rpm to get back up to speed. I would accelerate off idle and it will only go up a couple hundred rpm off idle. Sometimes it will clear up after 20-30 minutes and run fine. There is No consistent pattern to this issue. I thought maybe there was a fuel hose that was collapsing because of the ethanol in the gas, so I replaced all the hoses from the tank to the carb. along with the filter. The plugs have been replaced. There was no indication of overheating. I removed the carb. bowls and there was No sediment. I have also thinking the coil may be overheating had put ice on it, but made No difference. Any suggestions?

Thanks,
Tom
 
Does the fuel primer bulb have a a tendency to collapse?

Does pumping the fuel primer bulb (acting as a manual fuel pump) make a difference?

Start with the troubleshooting basics.................

Compression... what are the psi compression readings of all cylinders?

With the spark plugs removed... the spark should jump a 7/16" air gap with a strong blue lightning like flame... a real SNAP! Does it?
 
Hello,
Thank You, for your response! The bulb does not collapse and pumping the bulb did not make a difference. I will have to check the compression and check the air gap the next time I take the boat out. I am going to take a spare coil pack along and try that the next time I experience the problem.

Thanks again,
Tom
 
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