4630 Engine lope/ broken IP govonor spring?

So since my recent overhaul on my 4630, things have been good, but have noticed that my tractor seems to be lacking power in comparison to a newly aquired 4630 I just bought.

After talking with a tech that went to JD school the other day he mentioned to me that the govonor spring could be broken in the bosh pump causing the constant engine lope and the lack of power. When I mentioned that I turned up the injection pump screw to help power but didn't do much, he said that would be consistant with the broken governor spring...

Wondering if anyone else has heard this same thing? if this is indeed the problem, can I break into this govonor and replace the spring? or do I have to pay someone $2000 to go though this pump?

Thanks

DF

How many hours does the pump have on it? There may be severely worn plunger control sleeves allowing equal delivery to change between cylinders. The main governor spring can break, but if it does it will not speed up at all. If the starting spring breaks it will start harder as the rack will not be pulled to 21MM as it should. Low power can be a leaking aneroid boost line, keeping the max fuel at a lower setting with low or no boost. The governor bumper spring capsule should take out the surge, but not if the sleeves are worn.

not sure exactly of the hours on the pump since I bought the tractor used. if it's never been serviced, it could have 12000-14000 hours on it.

The new (to me) 4630 I just bought has had the IP already overhauled recently. The cold startup is neither better or worse between the old tractor and new tractor (both engines are overhauled with high comp pistons).

But, when both tractors start, the one with the new IP settles out, and runs smooth while my older 4630 sits there and lopes(at idle) (850rpm). only way to get it to come out of it is to raise the rpms up around 1000. after it warms up, it's better, but still notice a slight lope.

I've adjusted the aneroid and it helped low end some, but even if I back it all the way off the power just isn't really there.

Can I check any of these springs you speak of though inspection holes without taking the governor all the way apart?

I realize I'm beating a dead horse trying to limp an old IP along, but I just stuck a couple thousand in the engine with the overhaul, really don't want to put another 2K in it at this moment.

any basics I can check before I deem this pump no good?


A diesel guy told me also that there's a check valve somewhere on these pumps that supposed to regulate the in pump fuel pressure? maybe it's stuck open?

I agree with dieselteck. These pumps need to be run every 3-4000 hours because fuel delivery will vary between cyls. due to worn control sleeves , and loping at idle is common when this happens .

(quoted from post at 11:31:05 12/13/14) I agree with dieselteck. These pumps need to be run every 3-4000 hours because fuel delivery will vary between cyls. due to worn control sleeves , and loping at idle is common when this happens .

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Man I guess the inj pump on my 4255 is long overdue for check on inj pump stand as it has nearly 11,000 hrs on it with no idle rpm issues and hasn't been off the engine.

There are check valves in the supply pump assembly, but they won't cause surging trouble. The return should have an orifice fitting, no pressure regulating valve is used as the supply pump design controls the fuel pressure with the plunger spring. I would at least try resetting the low idle and bumper spring. Remove or back out the large capsule with the engine warm, then adjust the top low idle stop screw to 700 and lock. Finish to 800 with the bumper spring. This may take care of it IF the control sleeves are not worn badly. Most Bosch pumps will run fine with 10,000 hours or more IF fuel is clean and engine oil is changed regularly. I've also seen the sleeves worn badly at 4,000 hours too on both Case and Deere A size pumps as the sleeves are the same.

I would bet that everything inside is junk when you do. Out of balance can cause engine to fry pistons .