Diagnose my diesel problem

mikespence

New User
Long time lurker, first post. I kinda inherited an old JD 300b backhoe. I had problems with it not revving/stalling. I changed the fuel filter, but it was the same.

When I loosen the bleeder on the injection pump it starts up and runs good. When I tighten the bleeder it stalls or runs no faster than idle speed.

Does this indicate a clog somewhere?

Thanks in advance
 
300B has a 152 c.i. engine originally set up for a Stanadyne CBC pump but has been adapted for a JDB pump. Your pump has a plastic
(pellathane) shock-aborber ring on the governor weight cage inside the pump and it has fallen apart.
 
Like JDEM stated that is what is going on, and it has the return check valve plugged,, remove the return fitting out of the pump, and remove the check ball and spring from it,,blow through the return line and put the fitting back in,, it will run okay for a while, but plan on rebuilding the pump in the near future..
 
If you remove the return line check valve, be sure your fuel shut off cable is in good shape - the guy that did my pump told me that you
run the risk of a runaway
I had to do it on my Oliver 1755 - it got me through the haying season till I had time to get the pump rebuilt
Pete
 
My 1972 300B started doing the same as your's and I was around a 1/2 mile from home. As already mentioned, usually you can just remove the
check-ball from the fuel exit fitting as a temp fix. I did that to mine and I did not even make it that 1/2 mile. Big enough pieces of that
failed ring got stuck in my fuel return-line boots on top of the injectors. So I just left the return line unhooked, and drove it home with
fuel dribbling on the ground.

Note that when you fix it - you can put a new plastic ring in it for $20 in parts. Or - eliminate it forever with an upgrade for an extra
$50 in parts.

Several cars and trucks had that same problem in the 70s to mid 80s. In 1985, it was eliminated in new pumps for highway vehicles. If you
were to have a pre-85 Ford or Chevy pump fixed - that ring gets eliminated automatically.
 

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