Ford 4000 Won't Rev Up

[BAG]

Hello All,

About a year ago I purchased a Ford 4000 3 cyl diesel tractor. Based on the serial number, I believe it is a 1969 model. When I bought it all was well except the fuel pump leaked like a sieve. I found a post with instructions on how to replace the o-rings and got it done. I left the pump on the tractor and simply removed the top. I also replaced the fuel filter. After reassembling the pump, bleeding the filter and pump and bleeding two of the three lines at the pump, I cranked it up and it started. It seemed to run fine (no more leaks either) but the engine top speed seemed a little lower than I remembered. I shut it down and didn't restart it for several days. The next time I started it, the engine wouldn't rev much above idle speed. I've tried several times since with the same result. I was careful to note which holes the spring ends were in when I removed the spring and believe I reassembled it correctly. Because I didn't remove the pump from the tractor, I had to scrape the gasket off of the lower surface and try to catch the chips. My best guess is that a small piece of gasket or dirt fell into the pump and plugged something up. Does this sound plausible or should I be looking for another reason? I haven't cleaned the tank but the pump seems to be getting plenty of fuel. I cracked the bleeder bolt with the tractor running and got lots of fuel out without affecting the engine speed.

Any help would be greatly appreciated!

 

[Jerry/MT]

Hello All,

About a year ago I purchased a Ford 4000 3 cyl diesel tractor. Based on the serial number, I believe it is a 1969 model. When I bought it all was well except the fuel pump leaked like a sieve. I found a post with instructions on how to replace the o-rings and got it done. I left the pump on the tractor and simply removed the top. I also replaced the fuel filter. After reassembling the pump, bleeding the filter and pump and bleeding two of the three lines at the pump, I cranked it up and it started. It seemed to run fine (no more leaks either) but the engine top speed seemed a little lower than I remembered. I shut it down and didn't restart it for several days. The next time I started it, the engine wouldn't rev much above idle speed. I've tried several times since with the same result. I was careful to note which holes the spring ends were in when I removed the spring and believe I reassembled it correctly. Because I didn't remove the pump from the tractor, I had to scrape the gasket off of the lower surface and try to catch the chips. My best guess is that a small piece of gasket or dirt fell into the pump and plugged something up. Does this sound plausible or should I be looking for another reason? I haven't cleaned the tank but the pump seems to be getting plenty of fuel. I cracked the bleeder bolt with the tractor running and got lots of fuel out without affecting the engine speed.

Any help would be greatly appreciated!

Before I did any more to the pump I'd make sure the filters and the tank screen were clear. These older machines often have sludge from algae and bacteria on the tank bottom that restrict the screen on the tank valve. They can restrict the fuel flow and limit your speed. Also make sure your air filter is not clogged. If it's restricted you could have some problems with running.

If they turn out to be clean , then I guess you'll have to determine if you did something wrong with the pump repair. Someone with more experience with the injector pump than I have might be able to help you.

 

[BAG]

All,

An update on my original post...

It took a while to find the time but I finally got back to the fuel pump. I removed the cover and found that when I installed the arm that operates the throttle rod I didn't have it aligned correctly. The oblong hole in the arm was not lined up with the matching shape on the top of the rod so, although the throttle was against the stop, the rod had not turned far enough. Lesson learned is that I should have installed the arm while the cover was off of the pump where I could see what I was doing. Once the cover is installed, it's impossible to see around the spring and verify the arm is aligned properly.

 

[Jerry/MT]

All,

An update on my original post...

It took a while to find the time but I finally got back to the fuel pump. I removed the cover and found that when I installed the arm that operates the throttle rod I didn't have it aligned correctly. The oblong hole in the arm was not lined up with the matching shape on the top of the rod so, although the throttle was against the stop, the rod had not turned far enough. Lesson learned is that I should have installed the arm while the cover was off of the pump where I could see what I was doing. Once the cover is installed, it's impossible to see around the spring and verify the arm is aligned properly.

Thanks for the follow up. It's always nice to find out what the final fix was.