M934A1 NHC 250 PT pump goes to full throttle

[Over]

NHC 250 PT pump goes to full throttle. I had just reinstalled the PT pump on my M934A1 (NHC250). Finally chased down the lines I needed. Went to start and it went into full throttle right to grenade mode! Had to jump out and kill it with the shut off lever. I got it to idle by backing down the shut off lever. Throttle linkage off or on has no effect. Have the throttle shaft all the way clockwise. I replaced the return line hose also. I had messed with the pump when it was on another M923A0 but never went beyond the screen replacement.

 

[Monkeyboyarmy]

Fuel return line plugged or blocked?

 

[Over]

Wess sugested it was a stuck piston in the pump. I diconected the return line before the pressure reg to verify it wasn't a plugged return line. Time to try my hand at rebuilding a P pump.

 

[simp5782]

It takes a special kind of tool to get the main drive out without breaking it. Main drives are cheap it you do break it.

 

[Over]

Everythings cheap till you break it for sure. I have a full machineshop so hopefully if I need a tool I can make it. Being a FFL/SOT I work on 6k-60k HK's and assorted firearms daily. Some are pretty rare and parts are not around so you have to machine them. The projects themselves are expensive, I'm the economical part of the picture but it beats a regular job for the last 40 years, lol. I get baggie's with busted burst groups in them on occasion to fix, hopefully I won't be sending Wess a box of P pump stuff that rattles when you shake it.