Primer pump running before startup.

[1629dill]

I have a 1999 Suburban with a 6,5 TD that I am starting wander if I have some type of fuel system leek. When I turn the key on the morning it sounds like a pump is running. It is the same sound I get when I have run out of fuel or changed the fuel filter. Do you think I am losing fuel pressure and the primer pump is kicking on.

I do not see fuel on the ground.

What could be going on?

[suburbanK-2500HD]

dont worry, all ok.

Its building up pressure before and after start.

:)

[DmaxMaverick]

Agreed. The lift pump will run a pre-run prime cycle, then continue to run all the time the engine is running (or is supposed to, anyway).

If this is a "different" sound than what you've heard before, you may have an issue needing addressed. Often, it's a simple thing like a failed fuel filler cap vent (allows too much vacuum to develop in the tank, especially after a cool overnight off period). They're inexpensive, so don't bother testing. Just replace the cap every couple/few years (make sure it's a "Diesel only" cap).

Or, you could have a suction leak, allowing air in while it sits. These rarely show a detectable external fuel leak. Often, as simple as a poor seal at the fuel filter cap, a cracked fuel filter assy, or a line/connector leak.