‘77 70hp Johnson Repair and Carburetor Rebuild

[JBQIII]

hey there,

Im doing my first carb rebuild of an engine I just bought that worked when I bought it a week ago and then died a few minutes into running at the dock on its first trip. I found a small crack in the small hoses that connect all three carbs together. Does anyone know what spec works for replacing these hoses? Picture attached for clarity:

Also, any suggestions for any thing to look out for on a troubleshoot would be great as well. Won’t start but will crank. Compression (110,108,109) and 7/16” spark check went well so that’s good. Replaced fuel, spark plugs, and fuel hose as well. Hoping carb rebuild does it!

 

[racerone]

Compression should be around 140 PSI -----Perhaps test with a gauge or pull cylinder head for inspection.----You did already install a new water pump impeller I hope.

 

[RBoyd1971]

I've worked on lots of these old 3 cylinder motors with compression around 110 lbs and they ran great, so I would run it after cleaning the carbs myself. If it still runs bad start looking elsewhere.

 

[RBoyd1971]

As far as the fuel lines, I just use whatever fuel line is available at the parts store. If I remember right, that's 3/16" or so. Just take a piece with you when you get some. Stay away from ethanol gas and you will be good.