I also run on veggie oil but have switched to diesel trying to get it going again. My car stalled on a rather steep hill, diesel fuel filters were black and after changing and doing a few mile run around town were black again. Cleaned once more and seemed fine for a bit until that treacherous hill came back and the car died again. Car would start but die right away. Fuel tank screen seems to be fine and all the diesel has been filtered though now the car won't even start. New primer pump but can't seem to bleed all of the air out. Have done a few attempts at bump starting down hill but still won't turn over. Grumbles like it's about to but pressing the accelerator won't do a damn thing and the clutch just kills it again. Lift pump and the injectors will probably be the next thing to look at, though not simple. I've tried to be thorough in what has happened, please ask if you need more info and please help. This car never puts out smoke though has in the bump start attempts. Just checked the oil and it seems to be a little full, did I kill my car?

 

I am running on veg and have a similar sort of problem, although it runs OK on diesel. But it won't prime like it used to - when there is air, I push the hand pump and it is soft and just bounces back. Before, it used to expel the air, I'm thinking there is probably some sort of air by-pass mechanism and it is maybe gummed up.

Anyway if you have a similar thing, try this, it got me going on diesel again:

disconnect the return fuel hose which goes from the motor side of the fuel distributor to the top of the diesel main filter. then pump the primer, and hopefully after a while you will see fuel start to come out. IF that doesn't work, you can suck on that hose to create some back pressure, and maybe pump at the same time - diesel in the mouht is not pleasant but at least it's better than other fuels. Once you get it going, keep pumping until it feels like the air is gone.

It seemed that the distributor was getting full of air and the pump just couldn't pump it through without this procedure. I think my veg conversion is much more sensitive to air leaks than the standard set-up ,since it doesn't return the fuel to the tank but pushes it straight back to the intake - so if air is not expelled it just keeps going round and round.

I'm going to put a separate thread about my problem too.
________
FORD YAMAHA V8 ENGINE PICTURE