1976 Johnson 35 hp sea horse irregular idle and average top end.

[ianferron]

I have a 10-1/2 X 11 propeller and irregular idle doesn't bother me too much but it seem that is not reaching top rpm to the sound. I did cleaned my carburetor once. I don't have a good hole shot neither. It take a long time before I can get on plane.

I have that motor on a 14' cadorette fury that weight maybe 400-500 lbs.
I usually see like 18-19mph maximum. Seem slow to me. I've seen boat with same configuration go 10mph faster than my setup.

I ordered an 10 x 13 propeller to see if it would go faster as a few mechanic told me that would work better with my boat.
If anyone know what kind of RPM I could use and how to hook it up on my motor. That would help me to know what's going on. I should run around 5500rpm but without rpm it's hard to know.

 

[Handyman1]

Re: 1976 Johnson 35 hp sea horse irregular idle and average top end.

Hi you should check the compression and make sure both spark plugs are firing you could run on a single cylinder i had a similar problem mine was running like that had a bad coil you should double check the carb and and the fuel pump.

 

[ianferron]

Re: 1976 Johnson 35 hp sea horse irregular idle and average top end.

Ok Compression 120 top cylinder, 110 lower cylinder. Seem ok to me. Spark plug top cylinder is black, lower cylinder is clean with little gas deposit on it. So I have a misfire on that one for sure. What should I try first, coil or condenser or point?

 

[fireman57]

Re: 1976 Johnson 35 hp sea horse irregular idle and average top end.

Physically swap the coils and plug wires and see if the problem follows the coil. If it does just replace the offending coil if it doesn't then we will go to the next step

 

[ianferron]

Re: 1976 Johnson 35 hp sea horse irregular idle and average top end.

Hi Fireman, I mix my plugs this morning so not sure wich cylinder was misfiring. I took 2 new spark plug and marked them 1 and 2 and ran my motor in a barrel for 5 min. I took the plugs out and they were both black and slighty oily. My idle is very crappy, it seem that it's gona stall and go back to idle. It do that every 5 second. It's hard to tell wich cylinder is misfiring without putting the boat in the river and drive a bit at high RPM and then look at the plugs. Trust me, I don't feel going on the river right now lol. My motor is also hard to start wich could be a bad coil like u said. I have a 1966 evinrude 5hp wich was running like crap when hot and turn out to be the coil wich I both replace. It was working fine when cold but when warm was misfiring like crazy and hard hard time to get full rpm and if I stop it wouln't restart until the motor cool down first. I'll go look at a local store tomorrow to see if they have the coils for my motor and try that. We both think it's a coil issue.

 

[fireman57]

Re: 1976 Johnson 35 hp sea horse irregular idle and average top end.

before you do that take your plugs out and have someone turn the engine over and make sure that there is a mist of fuel coming out both holes. If you only get mist out of one hole then rebuild/clean the carb. Otherwise use timing light and let it idle in a barrel to check spark. It can run well cold very easily because if a coil is getting weak it stops working when it heats up. Make sure the engine is warm before you use the timing light. Hard to start is usually a carb issue because they will run decent on one cylinder.

 

[ianferron]

Re: 1976 Johnson 35 hp sea horse irregular idle and average top end.

I have plenty of gas in both cylinder. I will try to clean up my carb once more just to be sure. I don't have a timing light so I will have to find the problem without that tool. I said it was hard to start, it might take 5 crank before it start, I am actually waiting for parts for my electric starter. The things that bogg me is when I took of my plugs at first and one was washed with gas. Really think I was running on one cylinder.

 

[fireman57]

Re: 1976 Johnson 35 hp sea horse irregular idle and average top end.

swap your coils and check your plugs. If you have a cheap spark tester that will work too. At least you will know if you have some spark. to really test it though it needs to jump 1/2" and be bright blue.

 

[ianferron]

Re: 1976 Johnson 35 hp sea horse irregular idle and average top end.

Ok I never heard of a spark tester but I think they had one at Canadian tire for $25.
So this is what I did tonite. I bought one new coil and try it on both cylinder. Same problem. Clean and adjust points, same problem, switch both condenser, same problem, cleaned my carburetor really good, high jet been blow with air compressor. Check compression when warm, 90 first crank, 120 second crank on both cylinder. Whatever I do I always have the wet plug on cylinder #2. I also unplug one spark plug wire to make it run on one cylinder and cylinder #2 seem running a litlle better than #1 but still misfiring. I have a exhaust propeller and I remove a little door on the side of the foot so the exhaust would come out easier, it ran a little smoother that way. I did check the sparks and I've seen spark but not very strong to my point of view and it's the same for both cylinder. I am pretty good at mechanic but this one look very weird.

I am ready to pull my hairs of my head!!!

 

[ianferron]

Re: 1976 Johnson 35 hp sea horse irregular idle and average top end.

Ok, I think I am on the right way. I got 2 condenser today, why not changing them, they are only $7 each. I put them on and still some missfire at idle when cold but not as bad and run perfect when warm. . It also start much better. I can't get my hands on those Champion plug UL81C as they are rare, I run NGK B7HS. I heard the champion work better.

 

[ianferron]

Re: 1976 Johnson 35 hp sea horse irregular idle and average top end.

Would a lean mixture would cause misfire at idle?