Every once in a while I will go to start my truck and the the lift pump only runs for just a split second and shuts off, it normally runs for a couple seconds. Then when I go to start the truck my fuel pressure wont come up and the truck dies after running for 4 or 5 seconds. I turn the key off then try to start it again and it cranks for 5-10 seconds then the fuel pressure comes up and the truck starts. My question is there a relay or something that I could check the connection on? I looked in the relay box under the hood and couldnt find anything. Once the truck is running everything is fine and it only happens every once in a while. Any ideas?

 

I dont know about the FASS, but my Holleys only run for a split second with the initial key bump. And they'll run again if its left in the ON position for a certain amount of time without being cranked. But then when i crank it comes right on up - maybe that'll help?

 

I hope someone can answer this because I'm having the same problem, first on one pump and then on the new one I just installed, thinking the other one went bad! I only get a couple of clicks, not even a second or two of the pump running, and 0 pressure.

Help!

 

I could be wrong but I was always under the impression that the LP runs for that second or two just to pressurize the line to the IP and if the line still has the required pressure you won't here it run for that few seconds.

I know mine doesn't always run for a couple of seconds just a little push.

 

The ECM controls the pulse of the lift pumps. I believe the lift pumps used to cycle for around 10 seconds, but that has changed over the years, now it's only a second or so. I didn't notice the change until I started to use a Smarty which has all the updated DC software.

 

I may have been unclear in my description of the problem. Normally my pump runs for about 2 or 3 seconds and turns off. The pressure goes up to about 15 psi during that time then drops to zero untill I start the engine. When I have this occasional problem the pump runs just for a split second, the pressure only has a chance to come up to about 5 psi before the pump shuts off and the pressure drops to zero. When I try to start the engine my pressure doesnt come up so the engine starts and dies in about 5 seconds. When I crank the engine the LP starts pumping fuel after about 5 seconds or so and the engine starts and runs normally. My question is what would cause the lift pump to short cycle like this?

 

That's a sign of a failing lift pump. I've had a couple go out that way.

 

I don't think there is a relay for a stock set up. I believe the power for the LP comes out of the ECM.

What should happen is this.

Turn key on: The LP should run for about .5 seconds then shut off (I ussually see a pressure spike of about 5 psi)
Turn key to start and start engine then turn key back to on: The LP should run continuesly (Pressure should be stable at 14-15 psi)
Bump key to start and don't start engine then turn key back to on: The LP should run for about 20 seconds then shut off (Pressure should be stable at 14-15 psi)

I aggree with Mike, sounds like your LP is going south. I had a LP that did stuff like that before it was replaced.

Jim

 

Right now it happens pretty rarely so Im going to keep an eye on it. If it turns out to be the lift pump Ill be bummed, it a FASS with about 10000 miles on it.

 

The ‘98.5 and ‘99 ECMs will cycle the lift pump for about 2 seconds before a start. I have found if I let the 2-second cycle happen and do not start the engine, but turn the ignition off, it will not repeat the 2-second cycle. If your ECM has been updated with a new flash you will lose the 2 second lift pump cycle and get the 0.1 second cycle. The short time was done to help starting and I believe it was when the HO engines were introduced. Since I have been running the Smarty in my truck I have the short cycle time now.

If you are wondering about the health of your lift pump try this test:
*Turn ignition key on and wait for the lift pump to cycle.
*Start truck and then turn the ignition all the way off.
*Turn ignition key on and see if you get the long cycle.

Now if you don’t start the engine the lift pump may not give the long cycle.

 

I didn't realize you had a FASS, I read lift pump and thought stock pump.

Contact a vendor that will be able to help you troubleshoot.