My WOT RPM drops as I run for awhile????

[gary_tenison]

Need some ideas guys...My boat runs at about 4950 RPM wide open throttle after I warm up at the dock and take it for a run...then it starts to slowly drop...running at 4800, then 4750, then 4700... It seems to run very smoothly but I loose RPMs. What could be happening?

[99response]

You're fuel system may not be keeping up for those high flow rates, maybe change the filter and clean the screen at the bottom of the fuel pump.

-Chris

[gary_tenison]

You're fuel system may not be keeping up for those high flow rates, maybe change the filter and clean the screen at the bottom of the fuel pump.

-Chris

Its been a couple years since I did the low pressure filter inline above the fuel tank... However, I never cleaned a screen on the fuel pump. Does a 2001 5.7 Monsoon have a screen on fuel pump? How do I chk that? Is it hard to access?

[wienrdog]

Try the fuel filter itself first.

You 01 SSLXi w/Monsoon does have the screen on the fuel pump... Not sure about the carb version, but don't believe you'd put up those numbers with the LCR.

Edit - Fuel pump is near the oil filter.

Not hard to access - it's in the fuel pump itself, you just need to disconnect the inbound fuel line from the bottom of the pump after taking precautions to minimize the fuel spill that will happen. (Paper towel, catch cup, clamp on line).

Edited August 3, 2010 by wienrdog

[eyepeeler]

Its been a couple years since I did the low pressure filter inline above the fuel tank... However, I never cleaned a screen on the fuel pump. Does a 2001 5.7 Monsoon have a screen on fuel pump? How do I chk that? Is it hard to access?

Two years is too long between fuel filter changes. One bad tank of gas can clog a fuel filter. Change it every 50 hours.

[gary_tenison]

Two years is too long between fuel filter changes. One bad tank of gas can clog a fuel filter. Change it every 50 hours.

Changed filter, then used mirror to look into screen on inlet of pump. Screen ok. Dumped the gas out of the inlet hose and got little black chiplike pieces of grit. Enough that it may have made a diff. Ill let you know perf impact when I get it on the lake. Thanks

[wienrdog]

Those little chips likely moved up to the screen & their aggregate collection there likely caused the problem. Once you stopped for a bit, they settled back down into the inbound line & stayed there until you started using fuel fast enough to move them back to the screen. Nice job on thinking to dump the gas from the line.

[gary_tenison]

Ok - just back from Vacation...yes, the fuel filter change and pump inlet screen flush did the trick. I run steady at 5k rpm now. Even w 6 people in the boat I was making 42mph. It is running great.