David Brown

I have a David Brown 990 Selectamatic tractor for more than 10 years.

This tractor has been very reliable and is very tough.

Most recently I have experienced problems with the fuel. It looked like it wasn"t taking its fuel properly (sounded like running out of fuel, irregular idling)

I decided to change the fuel filters (which I do every year), once the filters changed, I bled the hole system and restarted the engine. My surprise was that it was still hesitating !

I added conditioner in the fuel, but no change again, then I inspected the lines for a potential hole, but everything was fine.

I presumed that the pump was functioning properly since it was pissing strongly when unscrewing the bleeding screws on the put.

The only thing that I did not do was taking a part the injectors, but before I go there is their something else I should do or that I"m missing since the injectors must be done by the Dealership, this is a big job

Observations: Radiator is full and tested (not heating), Fuel line is not blocked since I hear the fuel return in the tank, The problem seems to be amplified when the tractor is hot.

Thanks for your support

Check any rubber hose, on the suction side of the pump. Not sure what pump you have on it, my experience is very limited on diesel pumps. If its a rotary roosa master, they have a lift pump, which transfers fuel, into the main pump, has carbon vanes, that when worn, exhibit the same symptoms you are describing. The test/temp fix, is to put a small electric fuel pump (45 psi, or so), on the input line, to the pump.

check your air filter and breather stack for obstructions...dirt daubers almost welded mine shut a couple times.

i had one years ago that did that, was ready to send it in for a pump rebuild. remembered that it started doing it after a tank of fuel from a different supplier, got a tank from the original supplier and the engine smoothed out. the 990 was the only tractor that did that, the others ran fine on the poorer fuel. -john-