Runs poorly, cuts in and out when warmed up

[Rickjhmn]

I am the semi proud owner of a new to me 1971 Johnson 60hp, 60ESL. It starts and runs fine for about 15 mins then starts to sputter and cut in and out. The carbs were rebuilt with no effect. Has new plugs and wires with no effect. I am still thinking ignition problems. Any common faults/problems that cause these issues? Are there old threads that address this? Thinks in advance for the help!

 

[racerone]

Remove flywheel.----Remove stator and distributor cap.----Inspect anti-reversing spring.----Adjust breaker points.-----Clean all parts under there.------Where are the slow speed carburetor needles set at ?------Thermostat in good shape ?-----Fuel pump diaphragm replaced ?----Post results of a compression test.

 

[Boobie]

Do a cylinder drop test on it when it's acting up !!

 

[faztbullet]

Check battery voltage as if it drops below 10VDC or is overcharging it can effect amp.

 

[racerone]

the 1970 models used an overheat light and 1971 was first year for warning horn.

 

[racerone]

Replace water pump impeller.------Or at least test the warning horn.

 

[fdrgator]

OP says it has new plugs. What kind of plugs? Those motor did not run well on the original surface gap plugs. Should be running Champion QL77JC4