Low RPM at WOT

[pete F]

Hi all, I put this in the wrong area before so here I go again. In one of my 2002 GTX 4-Tecs, I will go at lower RPM at WOT and then it will kick in and go at full RPM and speed. It almost feels like it does not get enough water to push through. The engine will run a bit loud when not running at lower rpm, then all of a sudden it will run perfect until the next time I turn it back on. Could anybody offer an idea as to what it might be?

pete F

 

[kustomkarl]

It sounds like it is cavitation. Check the wear ring around the impeller, at the nozzle end. You'll need a 12" long feeler gauge to measure it.The clearance should be measured at the blade center and be 1mm or .040" If the gap is wider the wear ring needs replacing.