Miss fire on bottom 2 cylinders, 71 Johnson 100 HP

[Carlos1787]

It's a 100ESL71A and I am stumped with this motor. I don't know any history on the motor other than it has been sitting for a number of years. I can get this motor to run, but only the top 2 cylinders will fire (one on each bank).
Here's what I have done to try and solve the problem:

Compression test 130 on all 4 cylinders
I cleaned the carbs, they were pretty clean to begin with.
installed new plugs.
cleaned all electrical connections

I have good spark at all 4 cylinders, tested using a timing light, and a visual spark tester. The bottom 2 cylinders (one on each bank)are full of fuel and have wet plugs after I run the engine.

What do these two cylinders have in common that can cause this problem?

 

[Carlos1787]

Re: Miss fire on bottom 2 cylinders, 71 Johnson 100 HP

Just thought that I would post an update. I think I found the problem after some head scratching and more investigation. I took the vacuum line off the fuel pump and noticed that it's wet. That line connects to the bottom of the crankcase that feeds the 2 bottom cylinders. I'll have to wait till tomorrow to get a new diaphragm. Just thought I would post what I found so that maybe somebody else can save some time.

 

[Carlos1787]

Re: Miss fire on bottom 2 cylinders, 71 Johnson 100 HP

Well I didn't want to wait till tomorrow, so I bypassed the fuel pump and pinched off the vacuum line to the motor.... I still have the same problem. the bottom 2 won't fire.
there has to be something I am missing.

All Ideas are appreciated.

 

[emdsapmgr]

Re: Miss fire on bottom 2 cylinders, 71 Johnson 100 HP

That engine has two set of breaker points for the 4 cylinders. Any chance one of them is not working properly?

 

[Carlos1787]

Re: Miss fire on bottom 2 cylinders, 71 Johnson 100 HP

That engine has two set of breaker points for the 4 cylinders. Any chance one of them is not working properly?

That is the only thing I had not checked thoroughly. I did a quick visual on the points, and they look to be in great condition, so I put the flywheel back on. Last night I took the flywheel back off and adjusted them properly. I won't get a chance to start it again for a couple hours, to see if that took care of the problem. While I was there I cleaned up the timing advance, I was a bit sticky. What type of lube should I use under the breaker point plate?

 

[Carlos1787]

Re: Miss fire on bottom 2 cylinders, 71 Johnson 100 HP

Well I still have the same problem... off to the dealer to chat with one of the tech's there. If it's too expensive I am picturing a disassembled outboard to be parted out on an auction web site.