Sticky thermostat?

[Evinrude Trouble]

I have a 1982 70Hp johnson outboard J70ELCNB and i dont feel like i'm geting as much power as i used to. I have heard the alarm in the contorl box go off intermitantly every now and then and i know the motor has an optimal operating temp. When in WOT the motor sounds like somebody is moving the throttle a fraction of an inch back and forward in no particular pattern. Could this be the thermostat sticking open or closed? I know low temps lead to a carbed engine and i definately dont want that. Is there any way to test to see if the themostat is the culpert or does this sond like another problem. I have good compression and spark in all 3 cylinders and have recently rebuilt the carbs and fuel pump. I have been told that i could be "leaking spark" through my plug wires? Any suggestions on where to start?

 

[wilde1j]

Re: Sticky thermostat?

Not likely a thermostat problem, but they are easy to test. Just put the stat in a pot of water and heat to the correct opening temperature and observe whether the stat opens or not. OEM shop manual will have temp for you motor.

If you think the ignition wires are a problem, run engine after dark with the hood off and see if there are any discharges to ground happening.

 

[HighTrim]

Re: Sticky thermostat?

The surging you describes sounds as if there is an air leak in a fuel line. Carb bowls are getting emptied quicker than they are filled. Are your fuel lines original? If so, replace them. The ethanol in the fuel will break them down, clogging your high speed jet. Speaking of which, was it removed and thoroughally cleaned when you overhauled the carb? May also be an air leak in a fuel line, but as stated, if they are original replace them. If pumping the primer bulb causes the surging to cease, take a look at the fuel pump again.

The alarm you are hearing could be the fuel restriction if it is so equipped??

 

[tashasdaddy]

Re: Sticky thermostat?

82 does not have fuel restriction alarm. it also could be a coil failing, going in and out. also could be a bushing missing in the throttle linkage. i would try gas first.

 

[Evinrude Trouble]

Re: Sticky thermostat?

I repaced all the jets in all 3 carbs with brand new jets during the rebuild and the thing ran like a top. I have replaced the fuel line from the tank to the water separator, from the separator to the primer bulb, from the primer bulb to the in line fuel filter, from the fuel filter to the brand new quick connect. Have replaced some of the small tubing that branches to the three carbs. Would having too may in line things from the fuel tank cause this problem? how necessary is the in line fuel filter?

 

[tashasdaddy]

Re: Sticky thermostat?

not, with fuel water separator.

 

[Evinrude Trouble]

Re: Sticky thermostat?

do you think that that extra filter could be restricting the flow enought to make a difference at WOT? How do you test a coil to see if it's bad? next time i'm out i'll run it in the dark with the cover off to see if i'm getting any grounding spark

 

[tashasdaddy]

Re: Sticky thermostat?

the first way is when it is running, pull the spark plug wire, and listen for a change in the motor. usually pulling a wire, will drop the rpms. if it doesn't that coil is suspect. then you can completely change postions of that coil with a working one, it the problem follows the coil, replace the coil, if the problem stays with the cylinder, you have to decide if it is getting fuel, or if the power pack is not firing it.