Hi Stephenk,
It does seem to be Governor related and there is possibly an air leak or air restriction and just to make sure you will need to check out the Governor as follows:-
To check the Injection Pump diaphragm for leaks without pulling it apart, first remove the side plate from the Injection Pump and also detach the vacuum pipe from the Diaphragm housing on the Injection Pump, pull back the Fuel cut-off (the engine stop) now put your finger over the vacuum pipe adapter into the Pump and release the Engine Stop control which should remain stationary, you can also check the Rack in the Fuel pump (just above the four springs you can see when you remove the side cover), any movement will indicate a leak at the Diaphragm or diaphragm housing. You can then test the vacuum pipe by having it connected at the Fuel Injection Pump end and disconnecting it at the Venturi which is at the inlet manifold end. Apply a finger to block the Venturi end of the pipe and release the Stop Control as before, if the Stop Control or the Rack in the fuel Pump moves then there is a leak in the pipe. When I say "release" the Stop Control I mean just lift it up off the catch position that holds it in the STOP position, do not push the Stop Control in as you need to be able to see it move in the test.
If there is no movement in either of these tests, just lift your finger off the pipe or the adaptor and it should then move if the vacuum is good. To reset the Rack in the Pump each time you want to carry out the test, simply pull out the engine stop control.
Any movement caused by wear at the cross-shaft through the Governor Housing on the Injector Pump can cause a loss of vacuum, usually there is enough Vacuum created to withstand a lot of wear at this point, but if the housing is visibly worn then it needs replacing, don’t attempt to run the engine in work until this is repaired because there will be no maximum engine speed governing and it may rev at a dangerous speed and if allowed to run unchecked it could explode as it will be running at far higher speeds than it was designed to do.
Before you re-attach the adjustable rod to the Fuel Pump Governor control lever, you need to adjust it to prevent any “surging” in the engine revs. Start the engine and set the throttle lever to idle, at this point the engine may be “surging” but take the lever on the pump lightly in your left hand and push it rearwards until the “surging” JUST stops, at this point you need to attach the adjustable rod to this lever, altering the length so that you can re-attach it without moving the lever from the point at which the “surging” JUST stops.
Before you refit the side cover to the Fuel Pump, with an oil can, squirt some clean Diesel engine oil onto the springs and rack, open the tap on the side at the bottom of the Pump and allow the fuel/oil mixture to drain until there is just clean oil running out, then close the tap and replace the side cover. This should be done every month.
If the Diaphragm does require changing then the vacuum chamber requires removal, this is held on by four small screws, one at each corner. Once the cover is removed you can easily get at the Diaphragm to detach it from the Injection Pump. When re-fitting the vacuum chamber, do be careful to get it sitting squarely onto the Injection Pump and tighten the screws slowly and evenly, failure to do this may allow an air leak.
The Diaphragm is CAV part number 7034-19A
**You can also check the Breather on top of the Diaphragm housing as this can block up over a period of time and we have had a couple of these recently, so maybe that is worth looking at as well. (this is the domed cup toward the rear of the Pump on the top) You may find that when you remove the Side Plate, the Governor will start to work, this confirms that it is the Breather that is blocked or restricted. You should also make sure that the throttle link is attached to the Pump as this controls the Governor too.
If you check this and then let me know if it is OK, there is usually very little goes wrong with these governors apart from air leaks, but the tests will show them up. You can email me direct on
fergusontractors@hotmail.com as a lot of information is too long to send on here and some of it has pictures as well to help describe it ....John
Hi John,
I read we could ask you when a problem seems "hard" to fix. So I would like to talk about mine and see if ever you had ideas about how to solve it?
I have a 1952 TEF tractor whose engine seems to work fine: good power, very little leaks, no overheating, great idling, fast engine speed response when I move the throttle lever. But apart from that, the engine speed drops under load (as any engine would do) but doesn't go back to it preset level automatically, which I guess should be the case under the governor action. The load doen't need to be heavy, if I drive in second or third gear, the engine speed drops compared to what it was set in neutral (1500 rpm for instance). Same thing when ploughing or whatever.
If I manually pull the throttle lever down, the engine revs up with no hesitation. And when I get to push the clutch pedal down, and as the load is taken of, the engine roars until I move the throttle lever up. It is not conveniant to use the tractor this way.
The governor membrane looks good, the vacuum pipe isn't blocked up (I guess the engine speed wouldn't vary well if not).
I don't know what else I could check (by the way, the "little stick" inside the governor, in the middle of the spring, moves towards the back of the tractor when the linkage moves to accelerate, is that the right way?)
Do you have any suggestion to help me?
!
