Johnson 1982 7.5hp No Power Under Load

[seahorseinchatt]

I have a 1982 Johnson Seahorse 7.5 HP Model J8RCNR. After sitting for a couple of months it would not start. Isolated problem to no fuel to the cylinders. I rebuilt the carb to the best of my limited know how. Also replaced and gapped the spark plugs. The motor cranked right up and ran through all rpms. I took it out to the lake today and as soon as I engage the prop it barely lugs around and vibrates more than it should. It will occassionally speed up but it will eventually slow almost to stop. Out of gear it revs up normally. Best as I can tell from the schematics, this carb doesn't seem to have a high speed needle. Any ideas? Thanks

 

[Rick.]

Re: Johnson 1982 7.5hp No Power Under Load

"to the best of my limited know how" Isn't that what we all do? I wish I had limitless know how but I know I don't. I would go over that carb again unless there is something in the story you've left out. I assume it was running fine when you put it away for a couple of months? If yes then the carb is the direction I would go. Clean it better and longer and make sure you follow the cleaning with a good shot of compressed air. If it wasn't running good when you put it away you need to tell us that. Good luck. Rick.

 

[mthieme]

Re: Johnson 1982 7.5hp No Power Under Load

I agree with Rick.

 

[seahorseinchatt]

Re: Johnson 1982 7.5hp No Power Under Load

Thanks for the replies. The motor was running fine prior to sitting for a couple of months. I did not blow it out with compressed air. Is soaking the carb in gasoline ok or do I need something else?

One last item, I had always heard that I need to run all the gas out of the carb prior to any length of time of non-use. However, I saw a post earlier that said it was best to just use Seafoam in the gas and not run it out. What's the best? Thanks!

 

[Rick.]

Re: Johnson 1982 7.5hp No Power Under Load

I wouldn't soak it in gas. It shouldn't hurt it but gas won't clean it. You can get spray cans of carb. cleaner and you can get liquid that you can soak the parts in. Some swear by the soak method some use the pray only and some use both. Personally I have had good luck with either cleaner but I like the spray because it's faster and I can spray both directions through every channel I can find. The compressed air is a must as far as I'm concerned. In regard to your other question regarding seafoam or empty carb. I would suggest you start a new thread with that question. It has come up in the past but I'm not sure what the "party line" is on that one. I know you should only run the carb empty if you have a single carb engine due to the possibility of one cylinder being starved for fuel earlier than the other and therefore running the pistons dry. So... for multi carbed engines they leave the gas in without any problems that I'm aware of. I use a product called Stabil (Marine)and didn't even know Seafoam was a gas treatment until recently. I thought it was just for decarbing a motor, something I would strongly recommend if you haven't done it recently. Rick.

 

[seahorseinchatt]

Re: Johnson 1982 7.5hp No Power Under Load

Finally got around to pulling and cleaning carb again as spring is approaching and the fish are calling. I still have the same problem... idles great at all rpms, put it in gear and I could swim faster. I did check my fuel bulb and it was firm, squeezing did not change rpms. I did discover another problem that I don't believe is related but I'll mention because I will need help on it as well. After running motor in can, I removed it and as it sat, gear oil drained from the lower/inner exhaust port on the foot. Could this be related and how do I fix it? I assume it is a seal or gasket somewhere. Help pleeeze?

 

[ezeke]

Re: Johnson 1982 7.5hp No Power Under Load

You are most likely running on one cylinder. Try pulling the sparkplug wires one at a time with insulated pliers to see which one is not working, or use an inductive timing light.