J40ELCR WOT needs key pushed and released for full power

[JimLinton]

Hi All,

I have a new to me 1984 Johnson 40hp Seahorse. It turns on every time and idles great. When I go to cruise across the lake the speed really only seems to change the last inch of throttle and once at WOT I have to push the key in to get full power then it tapers off and I let go of the key and it full powers back up then starts to slow again until I push the key again. If I just leave it WOT it will slow off plane and I assume down to a sputter though I honestly haven’t tried yet. I put some snake oil in it to see if that would help and have ran through the gas tank by now so it should be all new gas. The guy actually cleaned the carbs for me after I bought it. Didn’t see him do it but he seemed pretty honest. Any thoughts on what my issue could be?

I can’t seem to get an image to load but added it to Imgur if helpful.

https://imgur.com/a/vsQpclE

 

[Crosbyman]

sounds like it needs fuel by choking.. inspect all hoses fuel pick-up filters throttle linkage , air leaks etc...

post mdl# and compression #s

 

[JimLinton]

sounds like it needs fuel by choking.. inspect all hoses fuel pick-up filters throttle linkage , air leaks etc...

post mdl# and compression #s

Ok I’ll go through and inspect the full fuel system.

What is an mdl #? Sorry, new to boats.

 

[Nordin]

mdl#.....model number.

 

[racerone]

Having to use choke would indicate fuel system needs attention.

 

[saltchuckmatt]

Carb....90%of the time.

 

[Crosbyman]

carbs... of course !
"The guy actually cleaned the carbs for me after I bought it. Didn’t see him do it but he seemed pretty honest."

spraying carb cleaner won't do it it needs a full tear down with all the intricate passages (orifices - jets- needles cleaned and air blown then adjusted. !

Being new to boating you should look up utubes on " how to" to help out.
and get a manual for your model.

Nothing miracoulous .. challenging the first time just something to learn to keep away from $100/h + shops.

your carb model is not identical to you tubes but they all originate from1950'S and later in some cases

site won't allow pictures to upload

this little 3hp carb cleaning wise.... is similar to your's except for high and low speed needles
design. modern ones have jets and orifices to replace needles which in the old days alloweed some adjustments but the cleaning process is very similar

1953-1967 Evinrude Johnson 3HP Tune UP Project Carburetor Tune Up | Outboard Boat Motor Repair

outboard-boat-motor-repair.com

 

[Crosbyman]

mdl#.....model number.

see it title !!

 

[cyclops222]

I would do the simple and cheap replacement parts. Like fuel hoses and a Primer Bulb. Before doing iffy expensive things. Maybe a new complete fuel pump. ........... Then start the testing and tearing apart parts that require real engine abilities.

 

[Crosbyman]

I agree yet nuts and bolts and carb cleaning may just involve a can of carb spray.. if gaskets are saved.

... But it could be a mine field to a newbie.

Aside from needles...replaced by a simpler HS jet and LS orifice that carb looks like most oldies carbs .

OP will have to decide if investing time to learn or shop time $$ is best .

 

[JimLinton]

I agree yet nuts and bolts and carb cleaning may just involve a can of carb spray.. if gaskets are saved.

... But it could be a mine field to a newbie.

Aside from needles...replaced by a simpler HS jet and LS orifice that carb looks like most oldies carbs .

OP will have to decide if investing time to learn or shop time $$ is best .

Thanks for all the feedback. I went ahead and got a gasket kit for the carbs and am going to give it a shot. I’ve done many dirtbike carbs and lawn mowers so I figure I could learn how to do these!

Fuel lines all look fine and bulb hardens up as it should. I did buy a new fuel pump as it wasn’t too expensive and I figure it’s worth a shot while everything is being worked on. Fingers crossed this all works out my issue!

 

[Crosbyman]

your high speed jets on the bottom of the carbs are likely plugged a bit. behind the bottom bolts. blow out with carb cleaner and air blasts

the carbs are very basic . while in there make certain the low speed side channel circuit is properly flushed out (small side orifice sends fuel to the top of the carb. probably ok since it idles good but may as well clean it all out.

clean out the HS channel and don't forget the fat donut

 

[saltchuckmatt]

I use gas welding torch cleaners...comes in a kit. Their like mini file pokers and a little vinegar helps.

 

[JimLinton]

Thanks for your help all! I cleaned the carbs, replacing gaskets along the way, and tossed a new fuel pump on. I did find a crack under the hose clamp on the out fuel line from the fuel pump and cut that section out but I don’t think that was the issue before as this time the bulb couldn’t get hard. Anyway, took it out and it ran like a dream! Thanks for all of your help.

 

[Crosbyman]

happy days... great thanks for your feedback

 

[saltchuckmatt]

Cracked fuel lines indicates replacement light unless you like trouble.

 

[JimLinton]

Cracked fuel lines indicates replacement light unless you like trouble.

Definitely replacing it before the next trip. Just clipped to get a test run of the new parts today