Evinrude 18 HP wont run well when hot

[rblanken]

I have a Evinrude 18 HP and it will cut out when ran after 30 minutes. It will run great when it is cold but after it seems to get good and hot it just doesn't want to run. After rebuilding the carb and checking the filter, it did not help any. I do not know what to do now. Can someone help me? Thanks

 

[tx1961whaler]

Re: Evinrude 18 HP wont run well when hot

It sounds like motor is overheating. When it warms up, can you put your fingers on the cylinder head for a count of three?

 

[ezeke]

Re: Evinrude 18 HP wont run well when hot

Your engine may be overheating, binding the pistons and causing the engine to stall.

You should be able to keep your fingers on the cylinder head for a full three count any time that the engine is running.

 

[tmcalavy]

Re: Evinrude 18 HP wont run well when hot

Caution...if it is overheating, you could burn your fingers badly. Feel for heat before touching the water jackets. If it's not overheating, could be a coil dropping out under heat/load.

 

[F_R]

Re: Evinrude 18 HP wont run well when hot

What year is that 18? Cutting out and won't run when warm are classic symptoms of cracked coils. That is, assuming it is not overheating.

 

[tashasdaddy]

Re: Evinrude 18 HP wont run well when hot

agree with F_R.

 

[samo_ott]

Re: Evinrude 18 HP wont run well when hot

Nobody has mentioned the obvious here. Have you serviced the water pump? New impeller? Is there spray coming out the back at all times?

And what year and model is it? It may or may not have a thermostat in it.

 

[Rick.]

Re: Evinrude 18 HP wont run well when hot

Good feed back so far so here is a shot in the dark. Just wondered if your tank vent is working properly. Try taking off the gas cap next time it happens. Be safe about it though. Rick.

 

[rblanken]

Re: Evinrude 18 HP wont run well when hot

Sorry guys it has taken so long of me to get back to you I am currently in college. Thanks for all the info. Ok, the motor is a 1970. We have never replaced the impeller. I do not think it is over heating but I will have to check. We are going to go ahead and replace the points and condesor. Do you think I should replace the impeller to? Since we have the fly wheel off, is there anything we should look at on the coils? I am sure that it is not the gas can. Thanks

 

[Mas]

Re: Evinrude 18 HP wont run well when hot

Impeller should be replaced about every two years...especially if it is not used...which is a bummer. If the impeller "sits," it begins to permanently deform and become brittle. The more it is used, the better of it is!

MAS

 

[rblanken]

Re: Evinrude 18 HP wont run well when hot

Ok, figures. The motor had actually sat in my grandpa's garage for I would say at least 15 years without being touched. It seems to shoot water out good though.

 

[Mas]

Re: Evinrude 18 HP wont run well when hot

Ok, figures. The motor had actually sat in my grandpa's garage for I would say at least 15 years without being touched. It seems to shoot water out good though.

I wouldn't want to be out on the water and have in impeller fail, motor overheat, and stranded. It's kinda like insurance and piece of mind, too!

MAS

 

[rblanken]

Re: Evinrude 18 HP wont run well when hot

I wouldn't want to be out on the water and have in impeller fail, motor overheat, and stranded. It's kinda like insurance and piece of mind, too!

MAS

Your right dude. I am going to go ahead and replace the impeller. Its not big deal. Just went out and looked at the condesors and they look like new and look like they have been replaced before.

 

[Mas]

Re: Evinrude 18 HP wont run well when hot

Get a spark tester and see what distance the spark will jump a gap. If it can jump 7/16 inch gap with a blue spark...you're good! This is a pretty good test of your ignition system's health. Good thing to do before buying a bunch of parts you do not need. The thing about outboards is that looks mean nothing! Test it out with a few simple diagnostics. You should also do a cylinder compression test to see what you've got. The PSI should be in the neighborhood of 100 psi and "relatively even" between each cylinder.

MAS

 

[rblanken]

Re: Evinrude 18 HP wont run well when hot

Awesome dude. I will let my dad know since I am going back up to my college tomorrow. Thanks again for all the help. Hopefully we can get this thing running good again.

 

[Mas]

Re: Evinrude 18 HP wont run well when hot

Good luck and keep us posted!

MAS

 

[F_R]

Re: Evinrude 18 HP wont run well when hot

So you think the condensers have been replaced. Big deal. The question is the coils. Your symptoms are classic. An old motor that won't run when warm. Extremely common.

If it isn't the coils, my next best guess is a spark plug wire that is arcing through where it is clamped to the bottom of the armature plate.

 

[tashasdaddy]

Re: Evinrude 18 HP wont run well when hot

if you like the motor, replace everything under the flywheel, and put an inpeller in it. you can do it all for $200 and have a reliable motor for the next 50 years. just change the impeller regularly, once you get the hang of changing it. it is only a 15 minute job. read this.
http://forums.iboats.com/showthread.php?t=281957

and this: http://forums.iboats.com/showthread.php?t=158086

 

[rblanken]

Re: Evinrude 18 HP wont run well when hot

I am sorry. I screwed up. I meant that someone has changed the coils before. I am just going to replace the points, condesor, and impeller for now. I will go ahead and test the spark and compression though. If the spark is back, which I dont think it is, then I will get new coils for it.