720d throttle/gov adjustments

JLG · May 28, 2017

I'm adjusting all the throttle linkages by
the book on my 720 diesel. Im wondering
about the spring that's inside the
cylindrical cover on the governor. This
tractor has the later style, and I've backed
the spring off to where I believe it's set
per the book. Seems ok there, might search a
very little.

Can someone explain the function of that
spring? If I tighten it a little more or
loosen it more, what will the effect be?
I've done it a little, but didn't notice
much difference. Thought if someone knew, it
would save a few hours of trial and error.

I'll tell you my trouble- it's pretty peppy
and is smoke free at lower rpm. At full
throttle with no load, it smokes. Seems like
with no load it shouldn't do that yet.
Pumps, injectors, cam, head, have all been
redone. Rack set per book.

Fine tuning for pulling. It's had some work
done but we have an identically set up
tractor that doesn't smoke until it's loaded
and has more rpm. Figure it's gotta be an
adjustment somewhere out of whack, but can't
pin it down.

Thanks for any help.

mkuhns · May 28, 2017

You have a fuel timing issue or poor spray injector spray pattern. Could also be lack of air. Governor will have no effect causing smoke at higher RPM's

JLG · May 28, 2017

I checked the timing, it's right on.

I thought about air. On the other tractor, we took out the oil bath and just made a pipe straight in. I haven't done that to this one yet because it requires making a new mount for the front of the fuel tank. So I just pulled off the rubber hose connecting the intake pipe to the oil bath housing for now. That's probably not as good.

I keep going back to injectors though. We flipped them around and spun the engine over to check. All the holes were functioning. Is it possible for them to look ok at low rpm but not be good at higher rpm?

The injectors have new tips and valves. I did however have trouble a while back. The tips kept getting clogged with something like steel wool. Cleaned the entire fuel system out then and took the tips to a pump shop where they were able to clean them. That had me baffled, but I was told there's steel wool inside the pump bridge as a filter. I replaced the pump bridge then too.

Because of all this, I first suspected the injectors, which is why we flipped them to check them. But maybe I need to pull them and get them looked at by a pro?

mkuhns · May 28, 2017

I'd at least pop them off with a tester. Pressure could be opening low, tip leakage, poor spray, etc. Could also have too much leakage which would spill too much excess fuel back into the intake from drain tube from the injector. The 730 gas we have, we gutted the air filter. Then found an air filter like a K&N to clamp to the original metal pipe in the center. It all looks original from the outside until you pull the lid off the bottom of the oil bath canister.

JLG · May 28, 2017

Thanks. I think I'll get them looked at.

720d throttle/gov adjustments

JLG

Member

mkuhns

Member

JLG

Member

mkuhns

Member

JLG

Member

Similar threads