'67 Johnson 100 hp

[Fisherman '78]

I have a '67 Johnson 100 hp outboard that isn't getting fuel into one cylinder. As a result the engine runs on three cylinders. The three cylinders that are running are functioning properly. I have checked the wires and plugs repeatedly and they are in good working condition. I ran a compression check and that was alright as well. I adjusted the carb with no results, then I sprayed cleaner into the adjustment hole on the carb. The results were the same, no fuel in that one cylinder. Any ideas?

 

[F_R]

Re: '67 Johnson 100 hp

Stuck float valve on the missing cylinder. Or clogged high speed jet orfice plug on same cylinder. That is actually 4 carburetors combined in a single casting.

 

[Fisherman '78]

Re: '67 Johnson 100 hp

Thanks for the quick response. Both the float valve and the high speed jet orfice are located within the front casting, correct? Someone recommended that I try spraying wd-40 into the carb adjustment while the engine is running. Perhaps to dislodge the float valve? Is that worth (or safe) to try, or should I simply pull the casting? I do not have a layout of this engine, so if anyone knows where I could find one please let me know. Thanks

 

[R.Johnson]

Re: '67 Johnson 100 hp

Finding gaskets' to put that carb back together, may be a problem, needle, and seats' may also be hard to find.

 

[Fisherman '78]

Re: '67 Johnson 100 hp

I think I have figured this one out. The casing next to the floats had some debris inside it clogging the bottom port. Thanks

 

[Fisherman '78]

Re: '67 Johnson 100 hp

In search of additional advice since my original diagnosis was incorrect. I cleaned some debris out of the carbs and thought I had remedied the problem. Originally I thought the engine was running on 3 cylinders, with the fourth not receiving fuel. This was incorrect, as the engine is actually only running on the top 2 cylinders. The lower 2 cylinders are not functioning. The wiring, plugs, and compression all check out. If anyone might know what is causing this problem your assistance would be greatly appreciated. Thanks again

 

[reload]

Re: '67 Johnson 100 hp

Does it fire if you spray mixture in the intake? How do you know it is not getting fuel? Is the spark plug dry or wet?

 

[Fisherman '78]

Re: '67 Johnson 100 hp

I am now running on three cylinders, with the fourth apparantly not getting gas. I am back where I started. I have already taken the front casing which holds the carb off and completely disassembled it. I found and cleaned some debris from the compartment by the floats. The floats are in good condition and free of debris. The pins and springs for the floats are in good condition as well. The reeds are in good condition. I checked the diaphram below the gas filter and it appeared to be in good condition. Wires good, plugs good. imported_F_R mentioned it could possibly be a clogged high speed jet orfice plug, however I am unsure where this is located. I appreciate the advice thus far, hopefully I can remedy this problem soon.