not enough fuel

[mybadford]

I know this is a common problem of engines surging. But my problem still seems to not be getting enough fuel. I have a 04 Mercury 60hp 2 stroke. I took it out for the first time this year and at high rpms the engine started surging. Of course the more I ran it the worse it got. Eventually the fuel pump went out. I replaced the fuel lines from the pick up tube all the way up to the first carburator. I've replaced the fuel filters and bulb. I rebuilt the fuel pump. It runs a lot better but still surges at high rpms.( between 5400 and 5600rpms depending on the load.) If I start pumping the bulb it runs good. If I back it down to 4600 it runs steady. It does have moments it runs good at around 5200 to 5300rpms. Anybody have any ideas how to get it to run good at W.O.T.?

 

[CharlieB]

Re: not enough fuel

Temporarily install a clear hose between the fuel pump and carbs, look for air bubble indicating the pump sucking air into the system somewhere.

 

[mybadford]

Re: not enough fuel

I will have try it out and see. I'm fairly confident that I have all the fuel lines tight, but that's not say that there isn't air getting into it from somewhere.

 

[ENSIGN]

Re: not enough fuel

Remove the pickup tube from the tank.there's a screen on the bottom of it that will get stopped up.

 

[mybadford]

Re: not enough fuel

I hooked the fuel from the tank and stuck it down deep in a can of gas. Still had the same issue. I haven't tried the clear tube yet. Could it be sucking in air where the fuel line hooks onto the engine? Don't know what that piece is called. The part that clips onto the engine.

 

[fastback4]

Re: not enough fuel

I'm wondering if that motor has a rev limiter because 5,400 -5,600 rpm's is a lot for a 60hp.
What prop size and pitch are you running? How big a boat you pushing?

 

[Jacket4life]

Re: not enough fuel

I'm with fastback---that sounds like awfully high RPM's assuming the gauge is reliable.

 

[mybadford]

Re: not enough fuel

It's a 17' Tracker Targa V17. I'm not sure of the prop pitch. Is there a number on it?It's what came on the boat and when it was bought new. What kind of rpms should it be turning?? As long as somebody is pumping the prime bulb it runs fine at those rpms with no surging, but that's not saying it's not over revving the engine. I think the tach is accurate.

 

[CharlieB]

Re: not enough fuel

When pumping the bulb cures the surging problem then the cause is either air leaking into the system between the primer and the fuel pump

OR still a problem within the fuel pump.

 

[fastback4]

Re: not enough fuel

I agree with CharlieB. Supplying fuel demand as needed by squeezing the bulb is an indicator of a system leaking pressure.....Tom

 

[fastback4]

Re: not enough fuel

I know this is a common problem of engines surging. But my problem still seems to not be getting enough fuel. I have a 04 Mercury 60hp 2 stroke. I took it out for the first time this year and at high rpms the engine started surging. Of course the more I ran it the worse it got. Eventually the fuel pump went out. I replaced the fuel lines from the pick up tube all the way up to the first carburator. I've replaced the fuel filters and bulb. I rebuilt the fuel pump. It runs a lot better but still surges at high rpms.( between 5400 and 5600rpms depending on the load.) If I start pumping the bulb it runs good. If I back it down to 4600 it runs steady. It does have moments it runs good at around 5200 to 5300rpms. Anybody have any ideas how to get it to run good at W.O.T.?

Perhaps the high speed jets in the carbs are clogged up........Tom

 

[CharlieB]

Re: not enough fuel

If ALL fuel lines are new then I would suspect the O-ring in the fuel line CONNECTOR. It seals when pressure is applied by the bulb yet allows the pump to suck air the rest of the time. You will never see the leak unless you test using the clear line AFTER the fuel pump to watch for the bubbles.