Hi everyone, i've got an 02 8.1 that recently has started occasionally sptuddering at idle and acts like its cutting out while cruising. The truck has a new fuel filter but power seems to have been going down since I got the truck 14000 miles ago and now acting funny. Thinking its a fuel pump but checker has several different pumps, Could this be a pump issue if so which part number do I need thanks guys.

check fuel rail pressure(idle and underload-driving), some fuel regulators have adjusting screws to raise pressure. read blog by gm techs, had similar problem and pressure dropped driving, mpg was down also. could not get pressure up, trick that got told and tried was to take 1/4in socket to fit over nipple and tapped down to apply more tension on regulating spring, symptoms went away and mpg's came up.

Check fuel pressure as noted above with a gauge sticking out of hood while driving. Had a clogged cat do this to me before on a 4.3L

Usually when the fuel pump starts getting weak you'll lose power at WOT, not usually just cruising down the road. Your symptoms sound more like a bad spark plug or wire. There are a few threads talking about plugs and gaps so check those out before buying your parts.

I had this problem a year ago. although my gas gauge was acting up too. bouncing around...saying full when it was empty. ended up having it towed, mechanic said i only had 8psi at the fuel rail and that he was surprised my truck even ran. well couple hundred later ended up being the fuel pump, sending unit. fuel filter. being an 2002, the guy said all the parts were original. and it had 125k on it.(90k hard miles since i have had it :) )

check fuel rail pressure(idle and underload-driving), some fuel regulators have adjusting screws to raise pressure. read blog by gm techs, had similar problem and pressure dropped driving, mpg was down also. could not get pressure up, trick that got told and tried was to take 1/4in socket to fit over nipple and tapped down to apply more tension on regulating spring, symptoms went away and mpg's came up.

Hey that's cool, as far as I know I came up with that socket trick and spread it around starting many years ago talking about this very subject.

As for the pump if they can't tell you find a Delco parts house and run the VIN. The pump numbers are on a label on top of the pump. Sometimes a flashlight and mirror under the truck can get them. You'll have to wipe the dirt off. It will be three digits, like GR8 or similar.

Vernon