1993 J50TLETF won't stay running

[Throbbin Rods]

Good morning,
I have owned this motor for 5 or 6 years and it has been flawless. Last fall it died coming back from a duck hunt and wouldn't start. Rowed the boat the 1/2 mile to the launch and parked it until warm weather. I pulled the input fuel lines from the carbs and there was no fuel pumping at all. Replaced the fuel pump and the pulse limiter, cleaned the carbs and the fuel pump was pumping like it should. Motor will start but needs the primer pushed in to keep it running. It always ran on an onboard tank so I tried a remote tank, no difference. I changed all of the fuel lines when I replaced the fuel pump. I have strong spark, new plugs.
I have installed a new fuel line and bulb. There are no air leaks that I can find.
I clean 10 - 15 sets of carbs a year to help friends out so I believe the carbs are all set. New gas, treated.
I would appreciate any input anyone might have.
Thanks,
Bill

 

[James R]

These motors are very reliable but like all they need regular servicing, especially the fuel side.
However they do wear out.
Starting from the beginning we need to do a compression test and a spark test. With those done and satisfactory we can take the next step. These motors will run on one cylinder so it is unlikely that both carbs have the idle jets or portings blocked, not impossible, but unlikely. It is possible that the idle jet settings are both wrong.
We may have more than one fault here. Could be the spark on one cylinder has failed but it is getting fuel. The other cylinder may have a spark but no fuel. To help in proving this you might try using a spray bottle with fuel mix, remove the air box and spray fuel into the carb throats separately and see what happens.

 

[oldboat1]

Carbs -- could depend on when you cleaned the carbs. If fuel in the onboard tank was contaminated, carbs would need to have been cleaned after use of that tank.