DB1 injection pump help (tractor similer to Ford?)

[subway]

my buddy has a david brown tractor with a DB1 rotary pump, are they the same basic pump as a IDI?

well lately the tractor is just going wide open throttle when he starts it. he has checked the linkages and every thing externally is fine. just tries to go full tilt any time he starts it.

could a internal governer spring have let go? could this be repaired by a DIY guy. I assume it is the pump since there is not much else and he dousent have a propane bottle next to him leaking or anything

thanks for any help

 

[Agnem]

The govenor tries to shut the engine down, while the throttle tries to open it. In between, balance is achieved. If that David Brown is like ones I used to be familiar with, the shutdown is mechanical. Since you can shut it down, it's not running on something other than diesel. So yes, something could have cut loose in the govenor assembly. If the pump is externally the same as the DB2, you should be able to pull the top cover and see the same kinds of things. I'd check to see if the plastic sleeve on the input shaft that the govenor arm rides on is intact. If it disintegrated, you may see the behavor you describe.

 

[colotow]

old saying from my diesel tech school days:

springs give fuel, flyweights take it away.

as the rpm's increase, the flyweights exert more pressure against the springs, reducing the fuel rate. stepping on the throttle puts more pressuse on the spring, until rpm's rise and again overcome the spring.

i'm not familiar (by memory) with your pump, so i can't help with anything specific. i would agree that it is inside the pump. could possibly also be leaking around the throttle shaft inside, or the flyweight pins could be worn and jammed.