fuel pump or primer bulb?

[mrprior]

i have a 1990 9.9 mercury and it wont start unless im pumping the primer and pulling the string at the same time. i have to do the same thing when i put it in gear but as soon as i get it in gear i can go WOT with no problem but when i bring it back down to an idle it will stall unless i pump the primer bulb. my primer bulb does stay hard. im leaning toward a fuel pump diaphram but i wanted to get some advice from the experts before i buy one.

 

[fasassvalk]

Re: fuel pump or primer bulb?

Has it sat for a while? or has it been being run and just started doing this?
Sounds kinda like a low speed jet plugged up.
I would think if the pump would not supply it at idle it would be even less likely to supply it under load.

 

[mrprior]

Re: fuel pump or primer bulb?

i just bought it so i dont know if it has been sitting for a while or the previous owner ran up until i bought it. if it is the jet can i run seafoam through it to clean it out?

 

[verado7]

Re: fuel pump or primer bulb?

nows the time to rebuild the carbs / fuel pump and change the primer bulb but keep the old primer for a spare - they do fail eventually . i say do that because the motor has been around and you dont know when it was done - not hard to do with some mechanical ability .

 

[fasassvalk]

Re: fuel pump or primer bulb?

It sounds like the symptoms of a motor that has been sitting for a while.
Fuel will turn to gum and crud. Alot of times the low speed sits lower in the bowl and when the bowls gums up so does the low speed.
I would go ahead and look at the carbs and see what they look like.
It is hard to buy a boat and know what it is going to run like under a load, people will sell it to you after you listen to it on a garden hose, and trust me what it runs like on a hose and what it will run like in the water under load can be two different things.