D330C CAT Fuel PSI

Can anyone tell me what fuel pressure this power unit should operate at? It has 2 fuel filters. The secondary has a bleeder and a fuel gauge, as well as what I think they call a tank assembly valve ( part # 8L8612 ). As soon as the unit starts to run I get a lot of fuel through that valve and the engine will not rev up. The engine has set for approximately 12 years. It came to me with 3 cut lines. One was a fuel supply line to the primary filter. A small return line and then this line that comes off the tank valve. Does this line simply run back to the tank as well? The fuel pressure gauge has not moved; It may be stuck. Will put test gauge on tomorrow and would like to know what pressure I should see? Thanks for the help.

Hi Ms0115,
I do not have a Parts Book to check but, from memory Industrial engines usually had fuel return lines. The line came from an adaptor bolted to the top of the fuel filter housing, on another type the line came from a big plug/bolt head type adaptor screwed into the filter top housing.

The fuel pressure is controlled by a valve and spring inside the bolt on adaptor or behind the screw in plug.
The standard fuel transfer pump pressure range would be from 25 to 32 PSI.
Cheers,
Eddie B.

The valve in question is the fuel bypass valve which should limit the pressure to the fuel filter to approximately 15 psi. This value is from a D330 manual, not the D330c, so there may be some difference there.

There should be a hose connected to the bypass valve that returns to the tank. The supply line to the primary fuel strainer is the only other normal connection to the tank. The small bleed line from the upper filter bleed valve usually just dumps on the ground, though it could certainly be routed back to the tank if desired for a stationary application such as a generator.

If your bypass valve is stuck or has trash in it, it will not maintain the correct fuel pressure, but it must be in place to limit fuel pressure developed by the gear type transfer pump. I am not sure having the fuel pressure being low would prevent an engine from revving up with no load, but I would start there and if it still won't speed up properly, then consider the governor and injection pump rack might be stuck or the governor severely out of adjustment.