I have a 1985 F250 with a 6.9 diesel. It will run but in not pumping fuel. I have changed the fuel pump. I still have the same problem. The truck has at least 186000 miles on it. The truck has two fuel tanks. When the fuel filter is full of fuel the truck will start and run for about 45 sec the die of lack of fuel. Any one have any ideas?? Thanks Eron

 

Try switching the tank switch and listen for the valve to click. It may simply be stuck in the half way position.

Another major problem which I don't want to scare you, is the cam lobe that works the fuel pump, is possibly worn down to the point that is will no longer provide a long enough stroke for the fuel pump.

 

Threr is 2 ways the lift pump will go on,make sure you have it on tke right side of the cam.Also check for fuel fron the lift pump to the filter housing.

 

My "86 will only run on the front tank. My valve switches fine so I am of the belief that my rear tank pick-up line is plugged. You should be able to break a line down stream of the filter to see if you are getting flow while cranking. Even if the cam lobe is wore down you should be able to fit in a electric pump for less than $100 bucks.

 

Pickup tubes in the fuel tank could be rotted.1/4 tank or less will cause problems.If you are 1/4 or lower add more fuel and try it again.