Lift pump ? or relay? or??
 

I have a 98 Silverado with a 6.5 that runs good until a hill comes up. Then is just doesn't pull. My 97 6.5 GM pulls like a bear on hills. This one downshifts on slight inclines and usualy continues to loose speed like it is starving.
I have been chasing this problem for a long time, PMD's, Grounds, filters, and a host of other things to no avail. last weekend I wanted some fire starter, so I put a bottle on the bleed line, and it pumps for about 2 seconds , 2 ounces and the lift pump shuts off. I have a new pump on order,it should be here in a couple days, but why does it stop pumping so fast? Is there a relay or switch that could also be part of the problem? and where is it ?
Thanks
Pete

a quick update : New lift pump and it is cranking out lots of fuel, and the cycle stays on . New Fuel filter installed with the pump. Now I go for a drive and take a run up a steep hill . It is still a dog, no noticeable improvement.
Any sugestions on where to look for a bit of power?

Do you have a lot of suction when you remove the fuel fill cap? Could have bad cap.

Install a fuel pressure gauge before the injection pump. Somebody has the parts posted someplace needed for a sending unit and gauge to leave on the truck full time.

Could be the sock in your tank. Sometimes they get crudded up and then the stuff falls away when you shut the truck off. Then eventually the stuff gets sucked back onto the sock.

When were your injectors last swapped. They say they should be checked or changed every 100,000 miles

Do the Feed the beast mod. It's not expensive and a good mod, no matter what

What is the "Feed the Beast mod?"

If you do not ave a fuel pressure gauge installed. Doing the feed the beast mod at the same time, would be good timing. You can install a 1/8" nipple into the FFM / Fuel Filter Manager then a T with a riser to the top of the FFM where you can get at it to install a fuel pressure sending unit.

I am just in the process of getting ready to do this myself.

Then go with the Feed the beast fittings and line.

This is a gauge that was recommended to me. https://bigbay4bestbuys.com/fuel_multi_gauge

Feed the beast search below:

https://www.google.com/search?q=Feed...+the+Beast+6.5

97 suburban
 

I am having the same problem with a 97 suburban all stock, but when mine goes into this no power mode, the fuel gauge also jumps around and it will pull hard for a brief second and then back to no power...have you made any progress on yours?

I finaly found and fixed the problem. The turbo sensor on the intake manifold and the solenoid . I just changed both and now I have decent power from stop to highway speed and good pulling power on hills.
I am not sure which one was the bad one or if both were , but I changed both anyway. Instant improvement and a cheap fix , that only took 5 minutes.