25hp Johnson won't start

[bwatson64]

hi everyone,

This is my first post although I have searched for solutions to my outboard problems for years and until now I have always found a solution.

Here is my problem I have a 1980 Johnson 20hp manual start. It has 125 compression in both cylinders, a spark that will jump a half inch. Timing looks OK. I cleaned the carb and it looking like its getting gas at choke. It won't start. Last year it did start but backfired badly. I had a bent reed and I fixed it. This year it won't start after 10 strong pulls all I get is a backfire.

Any suggestions?

Thanks

 

[Joe Reeves]

Re: 25hp Johnson won't start

Did you manually clean the brass high speed jet that is located horizontally in the bottom center portion of the float chamber?, if not, do so as fuel must flow thru that jet before it can gain access to any other fuel passageway. They do become clogged due to sitting.

 

[gm280]

Re: 25hp Johnson won't start

First welcome to iboats :welcome: ...

How do you know the timing LOOKS okay? There are four things any engine needs to run. Fuel, air, compression and timing. If anyone is missing nothing happens. So verify you do have all four of those things for certain. Is your keyway in good condition in the flywheel? If it is even a little sheared, that could be your problem... Also make sure your carb is clean and working properly too... And is this a 20HP or a 25HP? Your title says 25HP but you talk about a 20HP...not that it truly matter at this point but it can with deeper info needed...

 

[bwatson64]

Re: 25hp Johnson won't start

thanks for your prompt replys.


I checked out the high speed jet, it had some crud in it but it is now clean. I pulled the rope no go only backfired. Today a went to the store to get a socket to get the flywheel nut off 1 1/16". I used my puller to get the flywheel off. The key was sheared. Pulled a key out of another outboard installed and torqued to 105 ft lbs. Pulled the rope and it went!! I am going to fine tune the carb after it stops pouring rain.

The local evinrude dealer tells me they don't have a listing for a 1980 20hp so I call it a 25hp sometimes. Sorry for the confusion.

Thanks for all your help.