Still can't get Ford 4000 above 1500 RPM

Tom in TN

Well-known Member
Thanks to all who responded to my earlier message. My old-style (1962 - 1964) Ford 4 cylinder diesel was running very well. Last Sunday afternoon I was bush hogging with it and I had to keep opening the throttle a little more to keep the engine speed at 1800 RPM. Finally, I had the throttle all of the way open and the engine would only run at 1500 RPM.

Today, I:

1. Removed the fuel line that goes from the fuel tank to the fuel filter (gravity feed - no fuel pump
2. Had a steady stream of fuel. I collected two quarts of fuel in two glass canning jars. The fuel was clean with no trace of water.
3. Although I had replaced the fuel filter about 5 hours earlier on the proof meter, I replaced it again just to be sure.
4. The throttle linkage does not appear to have changed from earlier use. It looks like the arm on the injector pump is fully operating.
5. I removed the bottom of the oil bath air filter and ran the engine without any filter to see if it made a difference. It didn't.
6. I have a fairly large amount of bluish-white smoke coming out of the exhaust pipe, but no black smoke.
7. I had added some injector cleaner to the fuel tank about a month ago when I bought the tractor. The fuel tank is still a little over half full.

The engine starts and idles very well, but it won't rev above 1500 RPM. I don't know JACK about a diesel engine.

Is it possible that one or more of the injectors is clogged or not opening properly? Would that result in lost power? Do you think it is reasonable for me to pull the injectors and take them to someone who can clean and test them?

Thanks again for the help you've already provided. Any further suggestions would be greatly appreciated.

Tom in TN
 
I might be out on a limb here but when I bought my 671D, it would only run just shy of 1800. The previous owner had adjusted the high speed stop for the linkage where it goes into the fuel pump so they would never run it that hard. Owners manual should show it. IF this is what happened to you the lock nut may have been loose and it tweaked itself during vibration but just a thought. This would look like it is hitting the top stop. Can't explain the bluish light smoke though. This adjustment wouldn't cause any smoke. If you do adjust it- keep track of how many turns so you can put it back if no change.
 
The first thing I would do is check the stops on the pump. If it looks like a duck and talks like a duck...
So... with the tractor running at idle, slowly increase the speed with the throttle while watching the linkage on the pump. When it reaches the point where it no longer responds to throttle lever movement, look at the linkage on the top of the pump and see if it's bottomed against the high idle screw. If it's not, move the linkage at the pump with your finger and see what happens... I would say if it isn't bottomed out on the stop and won't respond to throttle... you have governor problems. If it does respond... you have a tractor related linkage problem. That kind of stuff happens on 50 yr old tractors...

Rod
 

getting air in??... run it and see if it bleeds out the air and runs better, if not go check for air leaks, stoppages gunk etc.

Or runing and while running use a wrench and crack each injector loose to see if the engine slows down or not. DO NOT PUT YOUR HANDS NEAR A LEAKING INJECTOR as it will inject fuel into your skin and make you have to amputate that part of the body. always use a wrench and carefully open...listen, then close. If the injector is good the engine will slow down, if the engine does not slow down, that injector is bad or not firiing. you crack or loosen the nut on the injector line at the top of the injector. If it does not fire, either the pump is bad, injector line is bad, or the injector is bad or the cyl is low on compression.
 
(quoted from post at 16:55:31 11/17/15) The first thing I would do is check the stops on the pump. If it looks like a duck and talks like a duck...
So... with the tractor running at idle, slowly increase the speed with the throttle while watching the linkage on the pump. When it reaches the point where it no longer responds to throttle lever movement, look at the linkage on the top of the pump and see if it's bottomed against the high idle screw. If it's not, move the linkage at the pump with your finger and see what happens... I would say if it isn't bottomed out on the stop and won't respond to throttle... you have governor problems. If it does respond... you have a tractor related linkage problem. That kind of stuff happens on 50 yr old tractors...

Rod

What Rod said x2
 
Bluish-white smoke out of a diesel can be a sign of a injection pump timing issue, especially if it is noticeable at all rpms but a little more pronounced under load. I cannot offer any advice on how to go about checking injection timing on one of these though. If the timing has slipped some over the years it may be a simple adjustment to clear up the smoke.

If you are going to pull the injectors to get them pop tested use that opportunity to do a compression test on all cylinders for future reference. Make sure you use a diesel compression tester with the correct adapter (maybe whomever you take the injectors to will be so kind as to loan you the correct adapter and tester while they have your injectors). Only takes a few minutes and provides alot of good information. Plus you do not have to pull the lines and injectors out a second time to do it.
 


How long did it take to fill the jars? The fuel should have gushed out like a cow peein" on a flat rock!

So you checked the fuel delivery to the filter, and replaced the fuel filter. Did you check the fuel delivery TO the injector pump? Were the fuel line fittings tight? You received some good advice here on possible causes from some of the most experienced people on this forum so you"ll have to follow up and do a thorough job of checking things out. The devil is always in the details. Something is limiting fuel delivery so you"ll have to check out all parts of the fuel delivery system between the tank and the injectors. If the fuel delivery is good to the injector pump, then the pump and/or the injectors could be the problem. If you have adequate delivery to the pump, and the fittings were tight, I"d bet on the pump personally but that"s just a guess. Look at the injectors only when you have eliminated every other possibility.

p.s. bluish smoke is indicative of loss of oil control in the rings. White smoke could be water vapor so look for bubbles in the rad indicating a head gasket leak.
 


white smoke can also be air in fuel, low compression, incompletely burned fuel, dirty/bad injector, or failing pump.



Did you by chance suck in a slug of water? Is the injector pump failing?
 

after rereading your oringinal post... hills and bumps... you probably knocked loose some crud, black algie, or a water bubble.
 
Check the Valve adjustments. If your intakes are opening the same time as the exhaust you will run low RPMs it happened to me. I removed and had my pump rebuilt and still had the same issue until I adjusted the valves.
 
Bill,

Thanks for the response. I think that I have clean, water free fuel in the tank. I drained two quarts of fuel into some Mason canning jars, and can't see any trace of water or dirt. I can shine an LED flashlight down into the tank and look through the filler opening, and I can't see any trace of water or dirt in the tank. I've replaced the fuel filter twice, with no improvement.

This tractor uses gravity feed from the tank to the fuel filter. It's a steel fuel line. I don't see any traces of fuel leaking from the line, so I sort of ruled out air getting into the injector pump, but then, like I've said before, I don't really know anything about diesel engines.

I have a service manual on its way, so I hope to check the injector timing when I get it.

Tom in TN
 
Wyman,

Your suggestion seems like a good thing to do. The odd part is that the engine was running fine and slowly (over about a 1/2 hour time period) just lost power so I can't get the engine speed above 1500 RPM. The engine starts beautifully and runs with no missing or hesitation, it just tops out at 1500 RPM and blows what I believe to be an excessive amount of bluish/white smoke.

Thanks for your response.

Tom in TN
 

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