1975 jonhnson 135 4th cylinder dead ????

[envader]

I have 120 compression, good spark, fuel shooting out of jet, and reeds look in good shape. New intake gasket. Have been through carbs twice. Not sure of the problem.

 

[chbailey]

Re: 1975 jonhnson 135 4th cylinder dead ????

Is that 120 measurement across all cylinders? Also, is your plug wet on the "dead" cylinder?

 

[Gary H NC]

Re: 1975 jonhnson 135 4th cylinder dead ????

If it has good compression and getting fuel you need to get a spark tester.It should jump a 7/16th gap on the tester with a bright blue spark.
Here is a link to a picture of the tester..
http://www.sjdiscounttools.com/the404.html

 

[envader]

Re: 1975 jonhnson 135 4th cylinder dead ????

yes my cylinders are all about 120 +. no the plug is not wet. yes i have use a 4 way spark tester spark is good 7/16 and blue.

 

[chbailey]

Re: 1975 jonhnson 135 4th cylinder dead ????

If the plug is not wet then your most likely not getting fuel to that cylinder. Which means I wouldn't run it until you can get fuel there cause your not getting lube either. Almost sound like you have a blockage on the engine side of the carb of that lower cylinder. Do you have something you can spray a shot of 50:1 fuel into the throat to see if it picks up the dead cylinder? This way you get some fuel in there to at least lube it.

 

[F_R]

Re: 1975 jonhnson 135 4th cylinder dead ????

Fuel shooting out of jet??? Does that mean fuel is spraying into the carb throat? Maybe, but is it the right AMOUNT of fuel. It has to be the proper mixture to burn in the cylinder.

Remove and inspect the high speed orfice plug for that carb side. It probably has something in it causing a restriction to fuel flow, making it too lean to burn.