Ford 4000 diesel engine won't go above 1500 RPM

Tom in TN

Well-known Member
A little over a month ago, I bought an old style Ford 4000, 4 cylinder, diesel tractor. It's in the vintage of 1962 to 1964. I've done a bunch of minor repairs on it - replaced the fuel gauge, replaced the headlight switch, rewired the headlights, changed all of the fluids in the tractor, replaced the fuel filter, cleaned the air cleaner, cleaned the rocker arm breather, adjusted the friction washer on the throttle bell crank, etc.

I ran it hard for about two hours today bush hogging some tall weeds/grass in a moderately hilly area. It ran very well, except, in the last 1/2 hour or so, I had to keep opening the throttle a little at a time to maintain the engine speed at 1800 RPM. Finally, I had the throttle all the way open, and the engine wouldn't rev up beyond 1500 RPM.

I quit bush hogging and went home. Now, with the tractor parked, in neutral, with the PTO disengaged, the engine won't run above 1500 RPM. I checked the throttle linkage to insure that it was opening the actuator on the injector pump all the way, and it is.

Any ideas what I should check next?

Thanks for any advice.

Tom in TN
 
JF,

Good point. I can easily detach the fuel line from the filter and see if the fuel is flowing well out of the tank. Tomorrow.

What's the old saying that goes something like, "Use it in on Sunday, fix it on Monday". Something like that.

Tom in TN
 

I can think of a couple things.[list:be6f371d50]

Fuel Filter at end of useful life.

Injection pump governor ring disintegrated.[/list:u:be6f371d50]
 
Larry,

I only have about four or five hours on the filter since I replaced it last week. But then, who knows what kind of sludge might have been in the fuel tank when I got it.

I don't know anything about the governor ring. I've looked for an IT manual for this model, but TSC doesn't have one, at least not at a nearby store. I can probably get one at the dealer.

Thanks for the response.

Tom
 
David,

Thanks for your response. The engine puffs some whitish smoke when I go downhill and let the engine hold the ground speed back, but I haven't seen any black smoke yet.

I think I'll pursue the possibility of a lack of fuel first thing.

Tom
 
showcrop.

Thanks for the response. I've never owned a diesel engine before, so this is all new to me. I understand that diesel fuel can develop some kind of slime if it is stored for a long period of time. I don't know for sure how long the fuel has been in the tank. I topped it off with a couple of gallons of fresh fuel when I bought the tractor, but I don't know how long the rest of the fuel had been in the tank.

I plan to disconnect the fuel line from the fuel filter tomorrow (maybe) and see if the flow seems to be restricted. Maybe I'll find something then.

Tom
 
Diesel can keep a -long- time. It doesn't go bad like gas. The slime you've heard about is algae. That can grow if water is in your fuel. But having water in your fuel doesn't mean algae WILL be there. Try opening the drain on the bottom of the filter and see if water comes out.
 
I had the same type of issue with a 1965 4000 diesel. After rebuilding the fuel pump I adjusted the valves correctly and it runs great. May not be your issue as it started and ran correctly after working on it. There is good links on here that will help adjust the valves Good Luck

Wyman
 
Most likely cause is a restricted fuel supply. Could be the tank outlet strainer, crud in the fuel line to the filter, the filter itself, the line from the filter to the injector pump. Some pumps have a screen on the pump inlet. If you have a lift pump, it could have an internal screen or it coud be screwed up.
I had a case where water in the filter froze and I went from 1800 rpm to 800 without touching the throttle lever. It was cold so I put a heat gun on the filter housing and then opened the drain and the thawed ice ran out. I was able to get it back to the shop and replace the filter.

So my guess is that your fuel supply is restricted and that"s limiting your rpm and power. I wouldn"t hurt to check your air filter also. It takes fuel and air to make power.
 
Jerry,

Thanks for the response. This morning I disconnected the fuel line at the inlet to the filter housing and drained two quarts of fuel into a couple of clear glass canning jars.

The fuel flowed steadily and there isn't any noticable water or trash in the jars. Although I only have about 4 or 5 hours on the new filter, I removed it looked at the base of the filter housing. There was no noticable dirt or sludge in there, however, when I looked down into the filter itself, I could see some gray sludge on the lip of the filter.

So, out of an abundance of caution, I'm going to replace the filter tomorrow and see what happens.

Tom in TN
 
Wyman,

Thanks for the response. I bought this old tractor about a month or so ago from a used equipment dealer. I've fixed a bunch of little problems on it, and heaven only knows when the valves were adjusted last.

That sounds like a good thing to look into.

Tom in TN
 

Do check the throttle linkage to make sure its moving the injector pump fuel lever all the way... Have seen problems with the linkage being bent or wonky. Also make sure cutoff cable is letting the fuel cutoff turn all the way "on"... rare, but has happened. If its barely on, it will do weird things with fuel.
 
Check every fuel flow element from the tank to the injector pump one at a time. You have free flow from the tank but do you have free flow into the filter itself? Crud could be in the supply line or in the filter head itself.
 
(quoted from post at 12:42:56 11/17/15) Check every fuel flow element from the tank to the injector pump one at a time. You have free flow from the tank but do you have free flow into the filter itself? Crud could be in the supply line or in the filter head itself.

He's done this. This tractor only has one filter!
 

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