That will be the external pump that supplies fuel under (relatively) low pressure to the unit injectors, of course. The injection pressure inside the unit injectors is much higher.
It would help if the original poster specified which pressure, and the reason they need to know it.
Thanks, Reason I was asking it was running and it quit like it run out off fuel I changed all the filters and tried to start it and it would not start took line off the fuel pump and it had little fuel coming out of it like no pressure, Do you think it is the fuel pump?. Thanks again
I think typically Diesel fuel systems need priming whenever they are disturbed.
There is a plugged port on the fuel pump to help accomplish priming, and some kind of special tool to prime the system, according to page 10 here -
It appears the fuel pump is a positive displacement gear type directly driven by the engine.
Thus >>IF<< is getting fuel at the pump inlet, the discharge will be practically an irresistible force.
Some Detroit Diesel fuel system pressure and volume specs are on page 47 here -
With unit injectors all air needs to be purged from the fuel manifold feeding the injectors. If there is even a small amount of air present in the fuel volume inside the injector, the air just gets compressed and will not produce enough pressure rise to unseat the pintle valve and inject fuel into the cylinder.
