What's causing this?

Friend of mine had a slight surging issue and after throwing parts at it, finally found the Intake Manifold sucking air. Replaced the gasket and runs perfect now. Might be something for you to look at.

What's the best way to locate that? I know u can use starter fluid on gas engines. But I don't know if that would be safe on a diesel?

With a hand held propane torch, you can run an unlit propane torch(with the valve cracked open very slightly) near the suspected area while your engine idles. If you pass it near a vacuum leak, it will idles up. Take the torch away and it will idles down. The propane going in the system will correct the Air Fuel ratio causing it to idle up.

An air leak on a diesel intake is meaningless, as the engine is not throttled like a gas engine. You could remove the intake manifold and it would still run fine. It could have a fuel supply problem or a problem with the governor.

Curtis, where is the governor and how do I check it? Also I currently have a new fuel filter in my garage waiting to be installed.

The_Hun said:

What's the best way to locate that? I know u can use starter fluid on gas engines. But I don't know if that would be safe on a diesel?

Click to expand...

To answer the question ether starting fluid or water can be used. Ether will speed rev up and water will rev down.

But unless that fuel injection pump is controlled by vacuum readings I do not think that is your issue. And looking here in multiple places I do not see a vacuum read to adjust fuel metering. http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.HomePageServlet_Alt

I would one at a time loosen the injector line at the injector and listen for a change in rpm. Be careful as the fuel can come out in a high pressure stream that can cause personal harm. If you hear no difference on one from the others then that is the cylinder at issue. Be it a issue with injector pump, injector and engine internals.