Primer bulb going soft

[mwm1179]

I have a older merc 115 hp ELPTO around 1988. Just had carbs rebuilt. Starts and runs fine at WOT. Engine stalls at idle and low speeds. When it does this it seems to be due to the primer bulb going soft. If I pump up the bulb the motor usually starts and runs fine again for awhile. Fule pump rebuilt last year. Any ideas?

 

[Vlad D Impeller]

Re: Primer bulb going soft

Check that the vent on the fuel tank is clear, make sure that all of the fuel line connections are tight with no air leaks.
If the problem still persists, it could still well be the fuel pump that is the culprit, if the pump is fine then your problem may be of an electrical nature.

 

[Nitro_boy]

Re: Primer bulb going soft

Check the check valve. could be restricting flow I'm going through something similar. Had pump checked and everything else was fine.

 

[Barnacle_Bill]

Re: Primer bulb going soft

When the motor is running its normal for the bulb to be soft as there is fuel flowing thru it. But it should not be collapsed.

 

[Chris1956]

Re: Primer bulb going soft

Normally a clooapsed fuel primer bulb is caused by a fuel restriction between the bulb and the fuel tank. Check the antisiphon valve in the fuel tank pickup fitting. They are a prime cause of this.

 

[AndyL]

Re: Primer bulb going soft

Have you tried borrowing a fuel line and portable tank from somewhere and run the engine on that. If that is OK then your problem is with your fuel system. Its then just a matter of checking each component. I had a similar problem which turned out to be a clogged filter on the tank pick up. Bit of a nightmare as the tank was moulded into the boat and there was no access to get to the pick up. Hope yours is easier!!

 

[Tech]

Re: Primer bulb going soft

Ask your local Mercury dealer about a service bulletin regarding this issue. There is a check valve kit that can be installed in the fuel pump that will help if there are no restrictions in the fuel line between the tank and bulb.