Prime bulb not pumping up hard

videorov

Cadet
Joined
Aug 31, 2003
Messages
14
When I pump the prime bulb going to the Yamaha<br />150 OX66 Saltwater series it never get firm.<br />My other motor is the same and the prime bulb<br />pumps like it should.<br />I took the drain plug out of the vapor separator tank and pump the bulb and fuel comes out like the book says it should.<br />I just don't get the prime bulb pumping right.<br />Looks like Im not getting fuel into the fuel filter bowl.<br />Oh I just put the new prime bulbs on both motors.
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: Prime bulb not pumping up hard

make sure the arrow is pointing skyward. the filter bowl may or may not fill up. also eliminate the check valve between the filter and the low pressure pumps. but always remember that the primer bulb is just that. once the VST is full you can toss it in the trash and hook the lines together and it will run perfect. all it does is insure the VST is full after sitting. is there any idle or running problems ?
 

videorov

Cadet
Joined
Aug 31, 2003
Messages
14
Re: Prime bulb not pumping up hard

No problems idle or while running once it gets<br />the fuel in. You say to take the check valve<br />out between the filter and the low pressure pumps? What is it there for?<br />Im not sure if I had the arrow pointing up to<br />the sky. I will try that too.<br />I start the motors once a week and run them for 5<br />minutes or more. Im going to put some fresh gas in the tanks in a few days. Its about 2 months old but has worked fine in the past.<br />Is there any good things to do to the fuel system<br />if the boat is going to be sitting for a few<br />months beside just starting and running the engines? I know there are additive but is there other things I should be doing?<br /><br />Thanks for your reply and help I can use it.<br /><br />Jack
 

reelly1

Seaman Apprentice
Joined
Apr 28, 2005
Messages
35
Re: Prime bulb not pumping up hard

Someone correct me if I am wrong but I think the check valave is there so that all the fuel does not back out of the line?
 

Ray Neudecker

Lieutenant Commander
Joined
May 25, 2004
Messages
1,656
Re: Prime bulb not pumping up hard

That is the purpose of the valve. Keeps you from having to pump as much to fill the chambers.
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: Prime bulb not pumping up hard

but why they used it on the EFI motors is beyond me. the VST cant siphon anyway so its rather useless. but if the arrow is not skywards on some bulbs the check valves in the primer bulb may not work correctly. but if the check valves in the primer are ok and it still wont get hard in can be an indication of a bad low pressure diaphram or a leaking needle in the VST. both will also cause idle and wot problems. thats why I asked. it is amazzing how well an EFI motor will idle with a blown low pressure pump. but it will idle a bit funny and leave a lot of fuel rainbows on the water when idling.
 
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