Losing Prime?

[MrGiggles]

I've got an 81 Mercury 9.8 that seems to lose prime now and then. You'll be going along and the motor will starve for fuel. If you let off the throttle it will usually pick up again. Once it picks up a steady stream of fuel it runs like a champ.

Sometimes the primer just feels spongy, other times it pumps normal and firms up when the carb fills like it should.

I've replaced the fuel line, it had the silver line on it and the plastic inner lining had come apart. Things have improved since, but it still acts up now and then.

I've also noticed that if you let it sit for more than 30 minutes, fuel will siphon back to the tank and you have to prime it again.

I've been through the fuel pump and replaced all the diaphragms. I have the line connected directly to the tank with a hose barb, so there is no air leak there. The quick connect on the motor is in good shape.

Kind of sounds to me like I should replace the primer? It's dated 2009, so probably due.

 

[Johnny]

if you had the silver fuel line and experienced the delamination issues
that it is known for, it is very possible there may be some trash inside
the fuel primer bulb..... it doesn't take much trash to interrupt the siphon
ability of the system. If the bulb is still soft (although the age indicates
that replacement is due), I would remove the bulb and inspect the insides
for any foreign matter. The little plastic balls and hose ends must go back
the way they came off.... new stainless hose clamps and try that.
if you still experience fuel delivery issues - it is time to replace the squeeze bulb.

maybe this article will help:

https://www.tinboats.net/primer-bulb-primer/


.

 

[overboard]

Two things to also look at, check if the primer bulb is somewhat vertical, and the fuel pickup in the tank if you have a portable tank.
If you replaced the fuel lines that were bad, and not the primer bulb, I would also say the problem is with the old primer bulb, I would look at or replace that first and go from there.