Logo
FULL SITE MENU

6HP Johnson Won’t Start

M

Mikeandike757

New member
I have a late 70s 6 HP Johnson (6R78B), that will not start no matter what I try.

When I first brought it home I was able to get it running but would only stay running WOT. I took the carb off to clean out, blow out, and replace any worn or damaged components, and after I put it together it wouldn’t fire at all. I am able to get it to start for a second with starting fluid, but no luck otherwise. I have ensured the spark plugs have spark, the fuel pump is pushing fuel (50:1) all the way to the port on the side of the carb, and the motor has compression (I have not measured it yet, getting a gauge today). Im almost certain the carb was put together correctly and have watched a million videos to double check everything is there, but there’s always a chance I messed that up considering nothing happens now.

Any help is greatly appreciated, Thank you.
 
Mikeandike757 said:
I have a late 70s 6 HP Johnson (6R78B), that will not start no matter what I try.

When I first brought it home I was able to get it running but would only stay running WOT. I took the carb off to clean out, blow out, and replace any worn or damaged components, and after I put it together it wouldn’t fire at all. I am able to get it to start for a second with starting fluid, but no luck otherwise. I have ensured the spark plugs have spark, the fuel pump is pushing fuel (50:1) all the way to the port on the side of the carb, and the motor has compression (I have not measured it yet, getting a gauge today). Im almost certain the carb was put together correctly and have watched a million videos to double check everything is there, but there’s always a chance I messed that up considering nothing happens now.

Any help is greatly appreciated, Thank you.
Click to expand...
Both Cylinders read 75psi on the Compression Test.
 
Put 6 drops of fuel in each sparkplug hole.-----Install plugs.----Try and start motor.-----Report exactly what happens.
 
Still waiting lol... I've got a 1976 Johnson 6 horse seahorse and it was running fine last year and I stored it on its back laying down in the garage... I go to put it on the boat and crank it up and the flywheel was stuck so I was able to break it free by turning it by hand not very hard and now trying to get it to start. I have verified spark at the spark plugs and squirted starting fluid in the carburetor and it will not hit. Any quick tips before I check compression on the cylinders?
 
See post #3 and report.----And does spark jump a gap of 1/4", yes or no ?-----The original head gaskets did not have a metal ring.-----They often leak between cylinders.------Note -----I own more than a dozen of these wonderful , simple reliable motors!
 
I've got a bad coil pack on the bottom cylinder, and a blown head gasket.... I turned it over to the boat repair man now. $500 to get it going again I think is well worth it versus the price I would pay for a new one
 
Back
Top