RoyM wrote:Did you check valve clearances? Ground the spark plugs in turn, the rpm's should drop off equally. If nothing happens on one it is not producing power. If the engine quits the other one is the culprit.
KE4AVB wrote:What pump are you running and do you have the correct tip installed? The tip itself needs to rate for the maximum gpm of the pump or one size larger. Here one of my customers is running Cat 66DX40GI1 using the 390. If I install the 4.0 gpm tip it overloads the engine. If switch to 4.5 gpm tip then it run at full rpms and at nearly full 4000 psi.
Suggest backing off the pressure regulator to 50% and work from back to the pumps max rated pressure. You do need a pressure gauge for this. That way you can tell where the overloading starts at. Also the 620 did have two different carburetors (depends on serial) and the wrong one may have been installed. Plus there is three different main jet sizes that can be used. If it is over rich you may need to downsize the main jet.
RMR wrote:That is his department, and he's been doing this for 30yrs. We've been working together on this, so I'll say the pump side of all this is right.
KE4AVB wrote:Also the 620 did have two different carburetors (depends on serial) and the wrong one may have been installed. Plus there is three different main jet sizes that can be used. If it is over rich you may need to downsize the main jet.
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