2002 EFI 60 hp. 4 stroke Mercury Bogging after 2 minutes running

[scubasteve49228]

I have changed the primary pump and fuel line from tank. The motor runs great except for 5000,-6000 RPMs then after 2 minutes the RPMs drop and fluctuate intil I bring the throttle to idle then after a minute it runs fine. Then again it does the same thing. I also pulled the check valve in the tank and it is fine. Also it gets worse as I keep repeating the above. I then return to the dock, let it idle then the same thing happens again. Thanks for any help.

 

[Silvertip]

Re: 2002 EFI 60 hp. 4 stroke Mercury Bogging after 2 minutes running

Sounds like fuel starvation due to a restriction somewhere. When the engine begins to die, squeeze the primer bulb quickly and firmly several times. If the engine picks up, you have a fuel delivery issue. Does the primer bulb get sucked flat by any chance which is also an indication of a restriction.

 

[daveswaves]

Re: 2002 EFI 60 hp. 4 stroke Mercury Bogging after 2 minutes running

I have changed out the fuel, primary pump and fuel line from tank. The motor runs great except for 5000,-6000 RPMs then after 2 minutes the RPMs drop and fluctuate intil I bring the throttle to idle then after a minute it runs fine. Then again it does the same thing. I also pulled the check valve in the tank and it is fine. Also it gets worse as I keep repeating the above. I then return to the dock, let it idle then the same thing happens again. Thanks for any help.

You are on the right track, it sure sounds like fuel. Bottom line the engine is consuming more fuel at that rpm than the delivery system can provide. If you have a water separator in the circuit that could be the problem. The filter swells and restricts flow. Try running a portable tank to isolate your boats supply system.

 

[scubasteve49228]

Re: 2002 EFI 60 hp. 4 stroke Mercury Bogging after 2 minutes running

I tried the squeeze thing, the primer ball is hard. It does not pick up RPMs until I back off the throttle for about 20 seconds. Then it goes back wide open then fluctuates back and forth until it almost dies. Almost seems like a electrical problem associated with the EFI? Also I do not have a water seperator.

 

[j_martin]

Re: 2002 EFI 60 hp. 4 stroke Mercury Bogging after 2 minutes running

I'd bet on a combination of dirt in the fuel and partially plugged injector screens.

Get the injectors serviced and flow tested (Brucato) and clean up the fuel system BEFORE you grenade the power head.

hope it helps
John

 

[scubasteve49228]

Re: 2002 EFI 60 hp. 4 stroke Mercury Bogging after 2 minutes running

I have to clarify my post. I Did Not change out the old fuel, I added SeaFoam and 5 gallons fresh fuel. Maybee there is moisture in the tank? Would this cause this type of problem?