Power Issues

[COOS]

Ref my 1989 Evinrude 48 SPL on a 15' Sunbird bowrider. Major power issue.

The boat has not been in the water for 3 yrs. When I pulled it last it was in and it was running fine. Have installed a new prop and gas is fresh. No old gas was allowed to sit in the engine or tank while out of use. There is a fuel water separator installed and the filter is brand new. The engine starts and idles fine. The motor is in great mechanical shape and has never been abused.

Problem: When I push throttle to forward, maximum power I can only get 2,000 rpms out of the engine and the boat will not gain speed at all. Goes almost at a "no wake" speed.

When I shift to reverse I get full power and there are no speed restrictions.

When I pull the boat and hook up a garden hose to the engine and shift into gear I can get 5,500-6,000 rpms with no problem.


Any help will be GREATLY appreciated!!! Totally perplexed

Thanks!
COOS

 

[racerone]

Your motor will rev to 5500/ 6000 because there is no work to do for the propeller.-----It will do that running on 1 cylinder!!----See if there is spark on both leads.

 

[COOS]

Thank you. I just came in from checking the spark and both are nice and blue from about 1/4" away.

 

[F_R]

Other things can also cause it to run on one cylinder. But since it was ok last time out, we can assume a couple of items are ok. What's left?

1. So, spark is ok. How about the spark plugs? Or arcing out before getting to the plugs?

2. No gas allowed to sit, eh? How about that last few drops that lie in the high speed jet? One of them is probably gummed up.

 

[F_R]

BTW, never admit you ran it WOT out of the water. That shows um--er--well let's say "inexperience" to be nice about it. IF it were running correctly, you could scatter engine parts all over the yard. Some maybe even through you.

 

[COOS]

Thanks for the advice. It was a quick up and down to see if I was getting more than 2000 rpms. Your input is appreciated!

1. Spark plugs are brand new.
2. Cannot rule out the gummed jet issue and will have to check into that.

Thanks very much!

 

[racerone]

What about the sheared flywheel key issue?----Might as well check for that.-----Post compression test values too.

 

[Tassie 1]

BTW, never admit you ran it WOT out of the water. That shows um--er--well let's say "inexperience" to be nice about it. IF it were running correctly, you could scatter engine parts all over the yard. Some maybe even through you.

Son did exactly that 10 yrs ago showing off his "new " $350 motor to his mate here in Oz
just as l came out the garage door saying " don't do that it will blow u... "
it did lol

spark plug and a sizeable piece of water jacket managed to fly between them and hit the back fence 30 yds away,
even blew a small hole in the front of the block, never worked out what that bit was

l like to remind him of that every now and them,
just because l can lol
He should've listened to the bald old geezer...

he just says " yeh, ok..."

 

[F_R]

I had a V4 blow up on me at low RPM of only about 1500-2000 right after startup. Sick engine, not anything I did. But the point is, it drew blood. Also, I knew a guy that got injured by an exploding flywheel. Pieces penetrated his skull. He never was the same after that.

 

[boobie]

When it's acting up squirt some fuel in each carb throat once and see what happens.

 

[COOS]

Thank you all for your responses and good suggestions. Pulling the carbs and cleaning them seems like the next logical step. Thanks again.