Need Help Repairing 7.5hp Johnson Seahorse

[fisherwayne]

Hey guys. I have a small motor that is my only means of locomotion on the water. Originally, it would not start and I rebuilt the carb. Now it works great in neutral but as soon as I put it in gear - it just bogs down and barely lugs along. I could swim faster. Anyway, I could keep trying stuff, but I'm missing a lot of fishing. Do any of you know someone who could work on it for reasonble (cheap) rate? or someone who knows engine that I could talk with? Fish are calling and I would really like to answer. Thanks! Wayne

 

[Shark]

I'm no where near an expert.... But; I had this problem one time with an 1955 older model 5.5 hp. My motor was getting air in the hose because the gasket around the gas tank dry rotted. That allowed it to suck in air and not get enough gas ( the gas can had a removeable top section with a gasket and about 30 screws securing that part to the rest of the tank). This is most likely not your problem. but wanted to tell you just in case.

 

[wrechin2]

What year? Did you buy it not running? Could be the sync off, points corroded (if equiped), damaged cylinder, ect. </p>

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[wrechin2]

Also could be you got the idle circuit cleand and the high speed is partially stopped up.

 

[fisherwayne]

Thanks for the ideas, here are more details. It is a 1982 Johnson Seahorse 7.5 HP Model J8RCNR. It has always ran great but after sitting for a couple of months it would not start. Isolated problem to no fuel to the cylinders. I rebuilt the carb and replaced and gapped the spark plugs. The motor cranked right up and ran through all rpms. I took it out to the lake and as soon as I engage the prop it barely lugs around. I recleaned the carb including blowing it with compressed air. Same result-runs good until you put it in the lake in gear. I have a firm fuel bulb. I was suspect of the bottom cylinder gettin good spark but works fine in the water barrel. I wonder if the coil might be weak though when it is under load. This carb does not have a high speed needle, just an orifice. Any ideas? Thanks=Wayne

 

[wrechin2]

That is what I am talking about. The high speed jet and the passage may be PARTIALLY clogged up. MAKE SURE you have no water in the fuel, water will get around a jet and lean it out. Easier for fuel to pass through a jet than water, especially a small HP engine may only have a .050 main jetI just looked yours up and it has a .035 jet. In order to test a coil it must be able to jump a large gap. I have a tester with 6 leads to test 6 coils at one for weak spark. You have a ADI Igniton that uses a powerpack, could run into alot with it. Can test if dropping spark under a load by instaling a inductive timing light on each cylinder and load it up on the water and see if it quits flashing, that will tell you if it is dropping out when trasition from low to high voltage on the stator but not the strenth of the spark. But change the plugs if you already haven't. Could be as simple as that. I rebuilt a 50 horse OMC that came to me in boxes. I put the plugs back in it that came in the head they looked new. It wouln't idle had to mess with the sync to get it to run. I noted when I pulled th plugs the #2 was COLD after being ran. Replaced the plugs and had to resync it because it was idleing really high. I repaired alot of boats that overnight developed a "bogg" under load with spark plugs, have had 1 turn out to be a mechanical issue. Hope this helps.