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kipps

Posted 4/4/2026 19:08 (#11607426 - in reply to #11556347)
Subject: RE: 'clogged' fuel injection pump?

Madison Co. Virginia

To update this post --

I pulled the pump, and disassembled it. I only briefly removed the distributor rotor from the head assembly, being careful not to touch those surfaces. That was mostly out of curiosity for what was in there, but I was also confirming that the various passages were not clogged. Everything else was torn down completely looking for problems. I also did not adjust the speed advance screw(green paint on #423), the leaf spring screws(barely visible in #387), or the pressure regulating screw in the input valve body(I likely should have tested that pressure and dialed it in, since I replaced the spring, but it ran fine as-is).

The 'no-start' issue was almost certainly a sticking metering valve(#381 and #416). It took a bit of playing with it to get it moving freely. The earlier poor idling characteristics were likely from the completely-disintegrated flex ring on the governor cage. Other issues I found were a broken delivery valve spring (#427, supposedly wouldn't prevent running; just would dribble fuel worse after the end of injection), a well-worn input bushing, a missing return check valve (not critical for operation but desirable), and somehow the charge pressure-regulating valve components had gotten lost during diagnostics.

I replaced the entire governor cage with a new single-piece cage; bought a gasket kit, input bushing, delivery valve spring, and charge pressure-regulating components. I worked with 'advance diesel systems' out of Alabama, dieselitems.com, and the guy who answered the phone was very knowledgeable and helpful.

Several things I wish I knew to start with -- use an impact driver on the lowest setting for disassembly, and only move up to an impact wrench if needed. Only sparingly use impact force for assembly if you're certain that part is strong enough to handle it. The cam timing screw needed the most force for both assembly and disassembly. An allen wrench fits the cam timing screw better than torx does, and plenty well enough that I didn't regret not buying the special spline tool.

The pump is assembled as either clockwise or counterclockwise, and that is ALWAYS while facing the drive end of the pump. The charge pump ring(#421) is stamped C and CC on each side, and needs to be flipped depending on pump rotation. For a clockwise pump, the C needs to face out where you can see it. I was confused, and thought the charge pump orientation was based on facing the rear end of the pump; that was incorrect, and required a bit of surgery in-situ to flip that ring around.

One video I saw too late to emulate, indicated that whole head assembly should be immersed in fuel before installing the plungers. That would have eliminated the air pocket that I most certainly had in there on first startup. As was, I had to start the tractor on starting fluid to build enough charge pressure to get rid of that air pocket. After the first start, the pump easily pumped fuel at starter speeds alone.

There's a washer in #421 that I couldn't immediately identify where it went. That actually belongs in the governor assembly, not in the charge pump assembly like shown in the photo.

Edited by kipps 4/4/2026 19:23