4-strock loosing RPM's

[CNT]

I have an 04 115 hp. Mercury 4-stroke that starts and idals fine. It has good excelleration and gets up to full throttle fast (5000~5200 rpms's) but then it creeps back down to around 3800 rpm's after just a few seconds. I can back the throttle back just a hair and push it back to full and it will pick back up to 5000 rpm's but it will fall back again after just a few seconds.

Anyone know what is going on? This motor has injectors and is not carburated. Gas and plugs are new, I have also ran seafoam thru it and still no change.

[flabum1017]

sounds like a fuel restriction. check for clogged filters, kinked or pinched hoses or a clogged vent. Put a hacuum gauge on the fuel line and see how much vacuum it's drawing, it should not be more than 3 - 4 inches,

[CNT]

Fuel delivery checked out. Still it looses RPM's. I can move the controller back and forth and it will pick up rpm's then back off again. Would a bad throttle positioner cause timing and or injector duration problems?

[VectorPat]

I dont think its electrical. The filter in the vst could be plugged or possibly the injectors.

[flabum1017]

The filter in the vst could be plugged or possibly the injectors.


:iagree::iagree:

[CNT]

OK,

I cleaned out the high pressure pump and all the injectors,and screans, then replaced fuel line and bulb, removed the small ballbearing and spring from the pickup line. The boat ran fine for about an hour and a half then went back to doing the same thing. It seams that I can pull the trottle lever back just a little and it will pick back up rpm's. Could this be a bad throttle positioner? Or, is there a rubber type impeller in the high pressure pump that may be going bad and maybee even coming apart and small pieces of the impeller are stopping up the injectors? That would be the only thing that would make sence why it ran good for a couple of hours after I cleaned it out and then stoped up again.

[CNT]

OH, the motor is a 115 hp 06 forestroke, not an 04