Case 1845c question! Fuel Starvation?

[Flying_gage]

Hey all,

Frickin winter! Another 6 inches here in the mid west! Although it does give me a reason to get out and play on the skid steer.

Here is the problem that started about 10 hours ago. It started "surging" while at about 3/4 idle. I changed the fuel filter and all was well. Then it did it again on my next usage about a week later.

It was still single digits and I am pretty certain I had some summer fuel in the tank. So I filled her up with fuel and hit it pretty hard with a "heet" type product, (formulated for diesel of course). Ran good.

Tonight after about an hour of full throttle plowing it started again. It actually died this time whereas before it would surge for a bit and stop. She fired right back up, but was surging. I backed the throttle off to about 1/2 and left it there for about 5 mins and she ran fine.

So what the F@#$? Any thoughts? I guess I should mention it has a cummins 4b with about 4500 hrs. It seems as though it is a fueling problem, but I am kind of at a loss. I just don't want it to be a injection pump going bad......

Thanks in advance,
Pete