Use a mirror on a stick, flash light and rag to see the pump if able. If it's metal, it is a pump-on-a-stick. Look for tag code and practice your'e reading backward. If plastic, it is a bottom-referencing type, that is an entire assembly. This is a tricky point for trucks, regarding mis-fire counting. As Manufactures where able to get CARB to roll back the mis-fire counter to keep CEL from being on everyday, they moved to the plastic bucket type that held fuel around pump during long turns with low fuel levels or acceleration when low. 1997 was a key year for changes but using the tag code and don't forget production date in door jamb. Regardless, over many moons of re-fueling events, dust gets into the tank and builds up. If the "Sock" of bottom filter on pump is really dis-colored and appears to have plugged pours on bottom, the tank should be removed and clean. Cleaning is done with empty tank, the hottest water you can get, agitate tank back & forth, then empty and dry by hand and evaporation in low humidity area. This procedure is in the service information for GM. Plastic bucket types, have two filters inside the tank. One on the bottom of the canister and one inside the bucket on the bottom of the pump. A pocket screwdriver will let you push-in 3 tabs on the bucket and slide off with fuel sender disconnected, then inspect the bottom and inside sock on pump. This will give you additional information as to the condition of dust, dirt or debris in tank. It does not happen over night. The ACDelco pump, installed at the time of build lasted 150k, why does a replacement fail after a few months? I just answered the elusive question. All of the pump manufactures, have people in the field who look at "Defects" in the pile at the warehouse distributor for date code, brand and reject payment on dirty ones. I have dozens of shops all over the mid-west follow this practice and reported back on what they found and how many pumps quit failing after seminar training discussions during the presentation. No one want to replace pumps and eat the labor and part. This is why.