dieseling

[fowbish]

I have a 502 that will not turn off. It will diesel for 30+ seconds. I know that not everyone is not having this problem, or they would sink their boat. It is uicker to turn the fuel pump off and wait 45 seconds BUT that is not always the case. What can be done?

 

[Croc1]

fowbish you can install an electric fuel cut off at the carb or do what I do is let the engine idle for 30-60 second after you run the boat hard this will let it cool down so the heat in the chambers will not ignite the fuel

 

[Rich Andrews]

have you tried sticking your foot to the floor to flood it out?

 

[Waterthunder]

Just install an idle solenoid their $80 from Jegs. What causes your engine run on is the throttle blades in your carb are opened up so much to allow the motor to idle that when you kill the ignition fuel and air continues flowing thru your carb and the hot spots in your combustion chambers are igniting the fuel and air. An idle solenoid keeps your butter flies at idle but when the ignition is shut off the throttle blades completely close this completely blocks any air or fuel from entering the motor and shuts it off immediately.

 

[Davie GSO480]

Try a colder spark plug....the A/C mr43, or 42 might help.....lower the idle to 600 or so,,,,,,the MR are marine plugs. made for constant load
The cumbustion chambers are hot......or hot spots are ignighting the fuel....
Run a 160 deg thurm stat

 

[fowbish]

I have replaced the solenoid twice, and it is set at around 600rpm idle speed. I am bowfishing out of the boat and ths is when I am having the problems. When running or pulling up somewhere I just turn the fuel pump off and wait about 45 seconds and it will shut down. I am using the boat for bowfishing and am at idle 98% of the time and when it is happening is when I am in a situation that calls for a quick shut down.

 

[Waterthunder]

You could do it manually say by using a Morse cable use a button cable like the aircraft guy's do for a choke then always run with it in this will set your idle stop but when you want to shut off pull it and the throttle will completely close and shut off the motor.

 

[fowbish]

That is what I have been doing, except I hae been reaching back with my hand and pulling it closed. I am going to try and see what happens if I shut it down and squirt several pulls of water into the carb and cool it off. I am fabing a front steering set up that will have throttle, steering and key on the front deck.

 

[fowbish]

took the boat to work and got my service manager, who turns 65 Sat and worked for us for 45 years to take the holley off and get the darn thing fixed, guess what, it Worked and he cussed the holley the whole time telling me how they have not changed since the first was he touched. Thanks for the info.