58' johnson hp

[2bolts]

looking for some help with my old johnson 3hp twin. My father had it since i was a kid and although I started it 3 or 4 years ago it has not run since. It wont fire, although I have lots of spark no fuel is getting to the cylinders as plugs remain dry. I've removed, soaked, cleaned and blown out the carb. The float and needle seem to be working and fuel bowl is full but I do not know how fuel is pumped or drawn through carb so I do not know what to look at next. Can anyone enlighten me.

thanks

 

[F_R]

Re: 58' johnson hp

looking for some help with my old johnson 3hp twin. My father had it since i was a kid and although I started it 3 or 4 years ago it has not run since. It wont fire, although I have lots of spark no fuel is getting to the cylinders as plugs remain dry. I've removed, soaked, cleaned and blown out the carb. The float and needle seem to be working and fuel bowl is full but I do not know how fuel is pumped or drawn through carb so I do not know what to look at next. Can anyone enlighten me.

thanks

If the carburetor is filling up with fuel the problem is elsewhere. But if it is NOT filling up, the sintered fuel filter in the gas tank is probably plugged with old gas gum. They are virtually impossible to clean--replace it. After cleaning the tank that is.

OOPS!!!, you said the bowl is full. If that is true and you have the lower knob open about a turn and the upper one about 1-1/2 turns, and are choking it, and it won't fire, it isn't a fuel problem.

Define "lots of spark". Will it reliably jump a 1/4" gap? Those motors are notorious for developing cracked coils with age. They have fooled the best of us, thinking it has "good" spark. I believe you can remove the recoil starter and the thin plate off the flywheel and look in and see the coils. If they are cracked, you are wasting your time till you replace them.

The plugs SHOULD be dry. If they were wet, the engine would be flooded.

BTW, Check your compression. Should be around 80psi.

 

[2bolts]

Re: 58' johnson hp

Thanks F R. I did not know what the settings on the jets were supposed to be and I will definately put my compression tester on it. The coils were replaced already a while back but were from from a doner unit which does not guarantee they have not cracked since. I believe the spark is good and my assumption was that if you have spark and fuel it should fire, however if the spark is not sufficient those plugs would be soaked. neither condition is true.

I will try some of those things this weekend and see what happens. Thanks again for your help.

 

[kbait]

Re: 58' johnson hp

When you're done w/compression check, squirt a bit of mixed fuel in the plug holes and try to start. If it fires briefly you have a fuel delivery issue from main jet to engine. Clogged high speed jet, Bad packing around high/low speed needles, stuck open reed (leaf) valve(s) behind carb are a few possible culprits.

 

[JB]

Re: 58' johnson hp

Go to the Top Secret file at the top of this forum. Do "Outboard won't start".

Let us know how you do.

 

[samo_ott]

Re: 58' johnson hp

When you're done w/compression check, squirt a bit of mixed fuel in the plug holes and try to start. If it fires briefly you have a fuel delivery issue from main jet to engine. Clogged high speed jet, Bad packing around high/low speed needles, stuck open reed (leaf) valve(s) behind carb are a few possible culprits.

I concur. Squirt premix in the carb. If it sputters or runs at all, its a carb issue. Could be gummed up slow speed circuits. Sometimes squirting premix and getting it running that way will help it clean up and run.