4000 suddenly running rough and losing power after warmed up

Anthony_TN · Aug 9, 2017

I've got a '68 4000 diesel that just all of a sudden started running rough and loss of power after it warms up. It'll run good when first started for a while, then start running rough and losing power. It gets progressively worse, and would barely pull itself up a hill getting the tractor back to the house. Next day it will start up fine, and do the same thing after working it a while. I've cleaned the air cleaner, put new fuel filter on it. No changes from that.I haven't messed with the fuel tank yet, but it seems to have a good flow coming from it to the filter. The two flexible fuel lines from the fuel filter to the injector pump were cracked badly, so I changed them in case it was sucking air in from the hoses. It ran fine for about 30 minutes after that, but then started acting up just like before.

So what should I check next?

showcrop · Aug 9, 2017

Describe "seems to have good fuel flow"

Sean in PA · Aug 9, 2017

Try loosening the fuel tank fill cap when the problem is happening. If that helps then the vent in the cap is clogged.

Anthony_TN · Aug 9, 2017

(quoted from post at 01:33:28 08/10/17) Try loosening the fuel tank fill cap when the problem is happening. If that helps then the vent in the cap is clogged.

Tried taking cap off, didn't make any difference

Anthony_TN · Aug 9, 2017

I didn't measure the flow, but the line going into the filter had a steady stream, I drained out what was left in the tank and it stayed steady, and put in 5 gallons of fresh diesel just in case there was water in the old fuel.

MJ in the UK · Aug 10, 2017

Hi Anthony, on the UK built tractors there is a small filter in the head of the injection pump and
you have to remove the fuel pipe from the filter to acsess it. Hope that cures your problem. MJ

Tequila · Aug 10, 2017

I had a 68 Deisel with similar problems. Sounds like a fuel problem definitely. Mine turned out to be the stand pipe screen in the tank.
Connected to the shut off valves inside pick-up, it sets in a slight depression in the tank. As the tractor vibrated or bounced around, debri would
get sucked around the screen and starve the pump. I removed the valve, cleaned the screen and then using a stiff wire with about 11/2 inch
right angle bent in it and wrap a clean rag around it I coaxed most of that crap out, problem solved. Perhaps that could be your issue.

Fordfarmer · Aug 10, 2017

I agree. I've had that problem with a couple of tractors I've bought.

Anthony_TN · Aug 10, 2017

Thanks guys, I'll check both of those out and see if it helps

Anthony_TN · Aug 10, 2017

Stand pipe screen was clean, tank had very little sediment. Didn't have time to try to get to the filter on the injection pump before dark. Maybe can try that tomorrow or saturday.

4000 suddenly running rough and losing power after warmed up

Anthony_TN

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showcrop

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Sean in PA

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Anthony_TN

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