motor dies after 20 seconds

[Buffalo79]

I have a 1978 Evinrude 85 hp. It has been a good motor, never any problems until last weekend. Went to start it it ran for about 20 seconds and died. Went through the same process of starting and running smooth for 20 sec then dying over and over again for 2 hours. I could pull the fuel line, and pump the primer bulb and it pushes fuel out so I know its not clogged line. I replaced the fuel pum today and it is still having the same problem. its getting fire on all cylinders. I am not sure what to check next. Really want to get it runnin before the weekend so any ideas are appreciated

 

[jbjennings]

Re: motor dies after 20 seconds

Your float may be sticking in your carbs. When you pump the bulb it forces some gas past the needle valve --just an idea. Did you rebuild your fuel pump or buy a new one? If you rebuilt it, you could have reversed a check valve and it won't work. I'd say it'd have to be one of the two.
JBJ

 

[Buffalo79]

Re: motor dies after 20 seconds

It is a new pump not rebuilt. Thats kinda what I thought, I am gonna pull the carbs and clean everything tommarow, just thought i would see if there were any other options I should try first

 

[oldpop43]

Re: motor dies after 20 seconds

have you checked the fuel filter? sounds like it might be about stopped up..using fuel faster than the filter will allow . if you changed the filter,be sure you have the arrow fuel flow in the right direction..good luck!!

 

[oldpop43]

Re: motor dies after 20 seconds

one other thing you might want to check is the fuel line connectors..does the bulb stay pumped-up tight when the engine stops? you have four carbs.if the float sticks on one, the motor should not die,but keep running on the three remaining...running rough...pop