Tef20 air leak or fuel problem under load

[Ole7070]

Hi all,
I've a few problems with my TEF20. Previously it broke down and it turned out the tank tap was blocked. I cleaned tank and got a sealant kit, replaced fuel filters and put it back together. It starts no problem and idles but on full throttle the revs go up and down and it engine dwindles in hill outside my house. I've replaced the diaphragm but not helped. I did notice the housing to the right of the diaphragm with the throttle link is packed with grease, can this be problematic with air ingress? I've attached a short vid where you can hear what happens on full throttle.
Any wisdom greatly appreciated

[Sandy.]

Hi Ole
Are you meaning the new bit on the end of the pump is filled with grease, sometimes there is a small amount of grease or oil just to lubricate the linkage. The tractor in the video I would say has got an vacuum leak between the pump and the butterfly in the inlet manifold. I also notice your tractor is an early one without a lift pump, with the tractor stopped have got a good flow of diesel when you undo one of the bleed screws on the side of the pump. There are also 2 felt filters in the back of the pump the pump has to be removed to change these, have these ever been changed.

Sandy.

[Ole7070]

Hi Sandy,
Thanks for the reply. Yes it's the one without a lift pump - seems to be a good supply of fuel to the cav pump.
I read online somewhere that you can test the diaphragm and air seal by removing the the inspection plate on the front of the pump and put a finger over the suction port and knock off the engine stop to see if there is any movement/leak. Mine still seems to leak even after a new diaphragm. Can these leak through the plunger /pin that comes up against the diaphragm? Find attached a pic of the plunger.
Can you also advise about the 'more fuel button' on the side of the pump? Since I've had this tractor, it needs to be pushed in to start and pops back out when the engine stop is pulled. Since the fuel blockage it now pops out just after the engine starts - is this the normal way it works?
Again, any information greatly appreciated. I've this small matter to attend to before the bigger job of splitting the tractor to replace seal/evaluate clutch & bearings

[Sandy.]

Hi Ole.
To test the diaphragm for leaks, with the engine stopped remove the side plate from the pump and vacuum pipe from the top of the pump pull the stop lever out then cover the hole on top of the pump with your finger. Once the hole is covered move the stop lever to the run position and watch to see if the rack moves through the side plate hole, the rack should not move or just move slowly to the end of its travel. This looks like the way you are already testing it.
There should be no leakage through the diaphragm center pin and the outside should fit into the grove.
The excess fuel button is doing what is should, pop out after startup.
The little piston in your hand is not very good.
Sandy.