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Evinrude 50Hp (2 stroke) only achieves half power

M

McFly

New member
Hello all, I have a 1996 50 Hp Evinrude SPL. It was running fine for the first half of the season, but something has changed. As the gas tank got quite low I put new gas in the tank along with oil for a 50:1 mixture. The engine started fine, and revved up to its normal high threshold of about 5000 RPM when in neutral and using the neutral throttle. But when shifting in to gear the power only comes up to about 2400 RPM, roughly half. When taking off the cowling and watching the throttle cable linkage, there is nothing obvious that I can see, although I really don't know much about outboards and what to look for. Seems like a throttle linkage issue? Hoping someone can steer in the right direction before I give it to the boat yard. Thanks!

Mike
 
Running at 5000 RPM in nuetral is NOT recommended !!------Sounds like it is running on one cylinder.----Test for spark .----Test compression.
 
Racerone - The rev up to 5000 in neutral was brief and only as part of my troubleshooting process. If it was only running on one cylinder would it still achieve full power in neutral? Seems to be two different results, when in neutral and when in gear.
 
Yes it will run to 5000 RPM on one cylinder in nuetral !!------Sorry , but why argue about it.-----Do the trouble shooting.-----I say the motor is running on one cylinder.
 
ok, thanks for the advice. I'll go tinker with it today and see if I can confirm both cylinders are in fact working.
 
Mcfly.... A engine in neutral has no back-pressure. In that condition (no back-pressure), running at a high rpm (anything over 1800 rpm) is inviting a runaway engine. A runaway engine suddenly becomes a diesel engine with it rpm steadily increasing until it runs out of its fuel supply. Turning off the ignition key or even yanking the spark plug leads off will do absolutely nothing. And by the time you can get the carburetor face plate off of that screaming meimmie to clog the fuel/air intake, connecting rods will be flying out the side of it! Consider yourself warned.

So it was right after you refilled the fuel tank that the engine developed a problem huh? Get access to the carburetor drain screws and check them for water.

Then, remove all spark plugs and take notice of the s/plugs working end appearance. Describe them.

Check the compression. What is the individual psi readings of both cylinders?

Check the spark. The spark at cranking speed should jump a 7/16" air gap with a strong blue lightning like flame... a real SNAP! Does it? NOTE that the 7/16" air gap is important!

Do not reply with generalities such as the spark is great, it has good compression, that sort of information doesn't tell us anything.
 
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