Diesel Question

I have been trying to figure out whats going on with my 1550 Oliver diesel. Its running a bit odd, Has plenty of power but when under a load it will rev up suddenly about 250 to 300 rpms faster for a min then slows back down to ware it was before. Talked to the local Oliver/White dealer they said its the fuel filters or a clogged sediment bowl screen. Well today I drained the tank and took the bowl off and cleaned it good, Nothing really there so I put it back on and put fuel back in. I then changed both fuel filters and cleaned the housings still no real problem could be found. I checked all the fuel lines from the tank to the filters and even the rubber line to the injector pump bled it out good and started it up and ran good.
After an hour on disking it started doing the same thing again with the sudden rev up when slow down. I just cant figure out what's going on with it. Tractor has 3300 hours in it and has all ways had farm diesel in it and is maintained regularly but its making me scratch my head on this one. It is a Rosamaster injector pump and is gravity fed as there is no lift pump. Anyone ever had this problem or know what it could be? Bandit

I would bet that the governor dampening ring is falling apart inside the pump. If it has never been rebuilt then it is over do for this to happen. Pull the return fitting out of the top of the injection pump. It has a check ball in it. Look through it and see if there is any small junks of black stuff. This is the rubber/plastic off the dampening ring.

The ring is not too hard to replace if you have had a pump apart. About the only special tool you need is a Bristol wrench to remove the governor ring ball/bolt.

Ditto what JD Seller stated bad governor damper ring in inj pump.

Ditto X 3, your hours are about right for flex ring failure. Don't run it so long that the retainer pins get broken off or you won't have a pump worth repairing when head locks up and drive shaft breaks.

I agree with the rest. Checking the return line fitting for chunks of rubber. Is a very good check.Best to replace the ring now before any real damage is done.

I always had the pumps rebuilt. Because with hospital back up systems. I could not afford not to.

Thanks guys, I was afraid it was something in the pump but was hoping it was not. I was hoping it would be something simple, But now I know that's not the case. I cant complain about this tractor, This will be the first big thing I have had to do to it since I bought it in 1988. But it couldn't happen at a worse time than planting season. Oh well if I have to I guess I can use dads 1550 to plant with. Bandit

,,that's the symptom of Rooosa master pumps on my 4020 deer and case 430..not sure what is on your Ollie . could be the fuel return line is choked with crud ,, and or debris from that governor...if the fuel return line is plugged it runs as if it has choke out like a gasser...