View Full Version : How Long should the lift pump run?

03-24-2007, 03:52 PM
How long should the lift pump run after the truck is shut off?

03-24-2007, 08:35 PM
Until the oil pressure drops below the minimum. Usually just a few seconds. The fuel pump power is relayed through the oil pressure sending unit.

03-24-2007, 08:55 PM
Thanks for the information!

03-24-2007, 09:31 PM
The control circuit for for the lift pump relay is through the ignition switch via the oil pressure switch. So when you turn the ing. switch off, power to the coil in the relay drops out before the oil pressure switch and the relay should open regardless of the oil pressure. I would say if the lift pump continues to run after the key is turned off the the relay is on it's way out. Ether the spring is getting tired or the points are getting pitted and sticking or both. Sometimes the points will weld themselves together and the lift pump will continue to run all the time because the load side of the relay is hot all the time. Hope this helps.

03-24-2007, 09:49 PM
Sixnickel, I always look forward to reading your post. Thanks for chiming in on this one. The pump runs about 8 to 10 sec. after the ing switch is turned off. (Thats probably more than a few sec.right hraney) I guess I'll have to go down and get a new relay for the truck. Do you think I would be safe going down to the parts store (Napa) or should I go to the dealer for something like this?

03-24-2007, 10:00 PM
Relays are pretty much universal. I'd have no problem with a Echlin relay from NAPA. My guess is it's re boxed from the same manufacture that makes the AC Delco.

03-24-2007, 10:05 PM
Thats good news. Napa is a good bit closer:D

03-26-2007, 06:51 PM
Yeah, I guess I should have narrowed that time frame a bit. 8 to 10 seconds is a bit long.
But hey, I do a lot of network consulting so I guess I am trained to give "grayer" answers than a lot of folks.:D
I second Sixnickel, pretty much relays are relays.

03-29-2007, 12:22 AM
Big thanks to you both! I installed the relay and things are as they should be again.

03-29-2007, 09:54 PM
would that be the fuel pump relay? My truck does the same thing...but only once in a while and I might as well fix it now if it's not too bad.

03-29-2007, 10:32 PM
That would be the fuel pump relay.