engine starts to slow after 45 sec run

[jcw1980]

engine starts to slow after 45 sec runs took it to shop and they cleaned and rebuilt carbs picked it up ran great on muffs could not get it off trailer it ran so ban took it back said carbs had water in them re cleaned them took it back to lake today ran for about 45 sec great then something put it on muffs started to get hot after 5 min on muffs very hot water coming from water hole the one that shoots it out real hard the tale or something any ideas compression is 145 on all three cylinders changed gas thank you for any help oh ya 1982 evinrude 75 hp

 

[jbjennings]

Re: engine starts to slow after 45 sec run

You really would be better off on your responses if you posted a year, model, and horsepower.

A few questions:
What motor are you talking about?
Why did you take it to the shop to begin with?
Is the motor new to you?
What did you do about the water in the carbs? Did you clean your tank and fuel lines/hoses?
Have you run the motor out of water, off the muffs at all?
If it's new to you, did you change the water pump impeller?
You said it ran great, then "something", then you put it on muffs. What's the "something"?


I'm thinking that if it's pumping water good out the tell-tale, but getting really hot, then you may have a bad thermostat. Then again, the water will feel hot at first as the thermostat begins to open, then gradually cool off and cycle over and over again. How does the cylinder head feel? Does it feel so hot you can't keep your finger on it for more than 3 seconds or too hot to touch, period?

There's no way for ME to even begin to diagnose your problem without more info., but there's lots of more knowledgeable folks here than me. Maybe they can.
good luck,
JBJ

 

[jcw1980]

Re: engine starts to slow after 45 sec run

sorry it is a 1982 evinrude 75 hp yes all of the lines were cleaned and gas replaced yes i have used it at the lake before i have had the motor about a month it gets hot i can put my finger on it for about 3 sec that's it and no i have not changed the impeller it ran at wot for about 45 sec burst and than started to slow down to an idle speed

 

[tashasdaddy]

Re: engine starts to slow after 45 sec run

get rid of old gas, replace all fuel lines from tank to carbs, with B 1 rated alcohol resistant fuel lines (ethanol in fuel now). to test get a portable tank, fresh gas and oil. running hot is usually, either thermostat, impeller, clogged water passages, or blown head or exhaust gasket.