79 johnson 15hp need help

[imported_doc]

79 johnson 15hp will hit and run a few seconds if sprayed in bottom cylinder with ether. this won't
work on the top cylinder. it has good fire although
i have trouble telling the difference in fire and hot fire.
compression and fuel system seem ok. flywheel key ok
plugs new. apparently timing is ok at least on the bottom
cylinder. any suggestions welcome.

 

[Xcusme]

Re: 79 johnson 15hp need help

Doc, Welcome to iboats.

Stop using ether, you're killing your motor, There's no lubrication in the ether. Use a spray bottle with fuel mix and spray into carb throat. Do a spark test on each plug wire and get compression readings. Guessing about the compression and fuel system won't get you running. Your motors timming is preset by the flywheel on the crankshaft with the woodruf key. If you pull the flywheel with a harmonic balancer type puller, inspect the flywheel key. If it's intact, you're timming is ok. If it's sheared or partially sheared, it must be replaced.

 

[DJ]

Re: 79 johnson 15hp need help

Xcuse me is dead on in his comments.

Don't make this motor into a monster, that it isn't.

You need things:

1. Compression on both cyl's. As long as they are close to each other-you're OK.

2. Spark-I think you have that.

3. Fuel- I doubt you have that as it was inended to be delivered. It's high time for a carb rebuild. Not to mention the water pump.

STOP the either/starting fluid!!!! You're KILLING it.

 

[tashasdaddy]

Re: 79 johnson 15hp need help

agree with their suggestions and ether is the quickest way to burn a hole in a piston, no lubrications and burns way to hot. takes little spark to set it off.

 

[imported_doc]

Re: 79 johnson 15hp need help

Xcuse me is dead on in his comments.

Don't make this motor into a monster, that it isn't.

You need things:

1. Compression on both cyl's. As long as they are close to each other-you're OK.

2. Spark-I think you have that.

3. Fuel- I doubt you have that as it was inended to be delivered. It's high time for a carb rebuild. Not to mention the water pump.

STOP the either/starting fluid!!!! You're KILLING it.

 

[imported_doc]

Re: 79 johnson 15hp need help

thanks for replys the compression is 110 on both cylinders. both plugs fire consistently. again the bottom
cylinder will hit the top will not. the carburetor is clean
and appears to be working . can you comment where
to look next. what about fuel intake reeds. the water pump has been replaced

 

[Xcusme]

Re: 79 johnson 15hp need help

Doc, try unbolting the fuel pump from the power head( 2 bolts only!). Work fuel bulb and see if fuel leaks out the rear of the pump. If it leaks, you have a broken fuel pump diaphram dumping fuel into the top cylinder flooding it out.