1984 Johnson 35 hp Help

[gmford1979]

Hey guys, new to the forum. Having a problem with a 1984 Johnson 35 HP. I'm going to give you the best description i can, but i'm not too mechanical. Got the motor given to me a few years ago. Motor wouldn't turn over when i got it.

We have the motor running pretty good now, but i has started messing up. It will run really great for 30 min then while in gear it just shuts off. It will crank back up and it feels like either too much fuel is getting to the carbarator. it almost starts spitting gas out of it.

Has anybody ever heard of anything like this or had any experiance with this??

Thanks

 

[tashasdaddy]

Re: 1984 Johnson 35 hp Help

how fast is it running, are you idling trolling, or running wide open.

 

[gmford1979]

Re: 1984 Johnson 35 hp Help

I'm not sure how fast its running. i'm thinking around 25 or 30 mph. for the first 30 min, it runs full throttle, idle, or trolling. it runs really good then just shuts down. once its off for about 2 or 3 min it will run good again.

 

[HybridMX6]

Re: 1984 Johnson 35 hp Help

Sounds like you are losing spark in one cylinder once the engine gets warmed up. Next time it does this do a spark check on it and see if one plug has spark but one doesn't. You can buy a spark tester at an auto parts store for around $10. You can do it the cheap way also and just pull the plug wires off while it's running poorly, but beware, it's gonna shock the crap out of you. If pulling one off doesn't affect how it's running, you aren't getting spark to that cylinder. If it does change how it's running, but doesn't die, you obviously have spark in both cylinders, since if you pulled one and it had spark, and the other one did not, it would just die.

 

[gmford1979]

Re: 1984 Johnson 35 hp Help

Ok, so we took the boat out and did a spark check on it. we are only running on one cylinder. do we need to start looking at the coil?

also we are having a problem with our carb. its blowing fuel out of it. not a whole lot, but enough that its a problem. its def not sucking in air like it should. is that sounding like the rings??

 

[gmford1979]

Re: 1984 Johnson 35 hp Help

bump bump..... any help??

 

[Doolin]

Re: 1984 Johnson 35 hp Help

Fuel comming out the front of the carb could be due to a sticking float. The fuel pump is always trying to put more fuel in the carb. The float raises in the bowl in the bottom of the carb as fuel fills the bowl. When full... the float raises high enough to push a pin up to block fuel flow.

If the float is sticking or the pin isn't sealing well... the bowl will over fill pushing fuel up through the main jet in the botton of the carb throat where it can run into the engine or right out the front of the carb.

 

[samo_ott]

Re: 1984 Johnson 35 hp Help

Yes, if fuel is spilling out that usually is the cause. Rebuild the carb to fix it. This will include a new needle valve and seat.

 

[gmford1979]

Re: 1984 Johnson 35 hp Help

we put a rebuild kit on the carbarator a few months back. I was thinking about the rings because of how hard the air was blowing out instead of sucking in.

 

[mafhuntfish]

Re: 1984 Johnson 35 hp Help

You also might want to check the reed / leaf valves in the intake. I just redid both carbs (with new floats) on my 55 HP & it was still spitting gas out of the bottom carb real bad. Pulled both carbs off & found a small bolt had gotten sucked through the carb & was stuck in one of the valves & had it propped open. I gently removed it & problem solved.

 

[gmford1979]

Re: 1984 Johnson 35 hp Help

ok, so i took off the carb and then opened up the intake. one of the pieces of the leaf valve was broken off. i searched for it and couldn't find it. there were some very small scratches on the piston though. do you think that is going to be a problem?? i have ordered a new leaf valve and gaskets. but what about the piston??

 

[samo_ott]

Re: 1984 Johnson 35 hp Help

did you take pictures?

 

[gmford1979]

Re: 1984 Johnson 35 hp Help

sorry no. i didn't take the piston out. just looked at it with a flashlight with the bypass cover off. nothing deep. but noticable when really inspecting it.

 

[mafhuntfish]

Re: 1984 Johnson 35 hp Help

The best thing would be to find the broken piece & remove it as to not cause further damage. You could try using a compressor & blowing the snot out of it through the bypass cover in all directions. You might be able to get it to pop out. Definitely wear safety glasses or a shield.

 

[gmford1979]

Re: 1984 Johnson 35 hp Help

ok, got the motor running great. replaced the leaf valve cleaned everything out good, and it ran awesome for a few hours. we rode out to the lake and ran it for a while. so we have a new problem now: after about an hour the transmission started "slipping". we had a low idle but anything else slipped. any suggestions????

 

[stevensmithnc]

Re: 1984 Johnson 35 hp Help

Maybe the prop is worn out and turning on the shaft

 

[gmford1979]

Re: 1984 Johnson 35 hp Help

how would i check something like that??

 

[stevensmithnc]

Re: 1984 Johnson 35 hp Help

take the prop off and check it out

 

[gmford1979]

Re: 1984 Johnson 35 hp Help

it is the prop slipping. i am going to get a new one tomorrow, but how do i tell the exact size. i know its supposed to be on the back of the prop but its not on mine. may have worn off being that its over 20 years old.