Fuel delivery issue

[fishinAK1]

I have a 1999 Mercury Bigfoot 9.9 outboard that I use primarily as my trolling kicker motor. Last year it ran great. This year it seems like it is having issues getting fuel. after running approx 20 minutes it starts coughing and dies. However, if every 15 minutes I go squeeze the primer bulb a dozen times then the ob runs fine.
I already replaced the gas hose and gas connector...no difference. Is this a bad fuel pump? If so is replacing the fuel pump a DIY job of a moderately mechanically inclined guy? Thanks for any and all help!

 

[Maxz695]

Re: Fuel delivery issue

If you pump the bulb a dosen time and the ball does not get hard you may have a carb issue. Rebuild may be recommended. When sqeezing the bulb is gas comming out of the carb? Can you feel the gas flowing through the bulb? Is the vent on the tank open or clear? A bad check valve in the bulb itself could be to blame try checking a few of the easier suggestions before moving on to the carbs

 

[fishinAK1]

Re: Fuel delivery issue

After 20 minutes and 12 squeezes the primer bulb DOES get hard and the motor WILL run fine for another 20 min or so.

 

[j_martin]

Re: Fuel delivery issue

It is obviously a fuel delivery issue. It could be either the fuel pump or a small leak anywhere in the line from the tank to the fuel pump, including the primer bulb and the pickup tube inside the tank.

It could also be a plugged vent on the fuel tank, however that will usually cause the primer bulb to suck flat.

If you temporarily splice in a piece of clear hose between the primer and the motor, you will see air bubbles if there's a problem. If that's clear, the next item would be to check the fuel lines inside the cowl for leaking. (just squeeze and hold the primer bulb while looking) If that's good, then you're at a real high probability that the fuel pump needs a kit.

hope it helps
john

 

[fishinAK1]

Re: Fuel delivery issue

ya, my main engine runs off the same pick up and no issues with it running...so I am pretty sure the lines are all fine.
So how difficult is it to rebuild the fuel pump? DIY? Can you buy a whole new pump, or is it way cheaper/easier to rebuilt the old one?
Thanks for the help!

 

[Mi duckdown]

Re: Fuel delivery issue

It is way cheaper to rebuild the pump. 20 bucks

 

[j_martin]

Re: Fuel delivery issue

Kit will come with destructions. Not hard at all.

 

[fishinAK1]

Re: Fuel delivery issue

Awesome thanks guys. Im gonna look for a kit tonite. I sure hope its the pump and not the carbs!

 

[Mi duckdown]

Re: Fuel delivery issue

J martin Kit will come with (destructions.) Not hard at all.
What?

 

[j_martin]

Re: Fuel delivery issue

kidding, just kidding.

 

[Mi duckdown]

Re: Fuel delivery issue

Buy my kits from local GOOD Merc dealer, Never got instructions.
I thought that was what the Merc manual was for.??
J martin( crusty) quit messing with my head.

 

[fishinAK1]

Re: Fuel delivery issue

Am i missing the joke here? are you saying it really IS a pain to rebuild the pump? Anyways the dealer didnt have the merc fuel pump in stock but he sold me a Yammi pump and said "yamaha used to make alot of parts for merc. this should be the same one. No we dont sell rebuild kits cause them are more than half the price of the whole pump and usally still have issues". So I reluctanly shelled out $90 for the yamaha pump, go home and of corse it looks nothing like the current fuel pump! Guess I have to run backinto to tonite to take that back.

If it is a pain in the A to rebuild a fuel pump, I may just replace the gas hose between the fuel seperator (this is where bot ob draw from a common) b4 ordering a rebuild kit. However, if there was a small leak in the hose wouldnt I see or smell gas leaking when it is all primed up?

thanks for all the HONEST help guys I apprecaite it!