331G Low Fuel Pressure

[mg2361]

That fuel pump should put out 0.25 gal/min of flow. Fuel pressure should always be positive when the machine is running, no load and loaded.

If the flow is that bad when connected to the fuel system, but OK when on a separate supply, then I would still suspect a suction side issue.

 

[MarkCanCTL]

We will test the system before ordering a new pump by running a new fuel line from the tank to the pump. Cheap way to check since I cannot see the entire length of the stock fuel line. We blew air through it without trouble. But just checking to be sure/redundant. We will also vacuum test the stock fuel line. It seems to be tight, but it’s another cheap test before ordering that pump.

 

[mg2361]

Has the water separator filter head been thoroughly checked for any debris or air leaks? Is the fuel shutoff valve on that filter head fully open? Loose and sucking air there?

 

[MarkCanCTL]

Yes. There was no water. The filter is clean. We even took that entire filter housing out of the circuit to see if that was a source of excessive resistance to flow of diesel to the lift pump. It made no difference. The problem persists.