I just replaced my fuel pump on my 1995 C1500 this weekend (Bosch fuel pump and spectra premium sender unit). The old fuel pump/sender was original and giving out. Since replacing the new one, my truck’s fuel gauge will fluctuate with the amount of gas given. Sometimes when I accelerate hard, the engine seems like it’s not getting enough fuel and greatly lower my acceleration rate (versus the original unit). When I let off, the gauge will drop 1/4 of a tank. It’s also starting to idle rough. It idled fine when I first installed it, but has gotten progressively worse. It seems like it doesn’t have pressure, but I replaced the seal when I replaced the pump/sender. It also will run rough when I’m maintaining a certain speed and then slightly give more gas like to speed up a couple MPH or when maintaining my speed going up a slight hill. I have no idea why it’s doing this. It’s my daily driver, so I need it to be reliable.

Thanks for the input! I have done Injector cleaner, but I have not checked the pressure yet. I pulled/tore a muscle finishing up the truck, so I’ll have to wait till this weekend or next week to check the fuel pressure.

I’ve been confused becuase it didn’t have this problem until I replace the pump and sender. I wasn’t getting enough fuel with the old one and my gauge was jumping, but nothing like what it’s doing now (it would just increase when accelerating, start to die if cruising past a certain speed, and gas gauge would show more than full). Could the tube from the pump to the send come lose? Or the ground not be connected properly? I’m trying to see if I messed up installing it, but not entirely sure what I would have done wrong

Another thing I’ve noticed is that I’m burning gas at a ridiculous rate...like been through 1/4 of a tank in 30 miles. I normally get about 10 miles per gallon, but now it’s ridiculously poor

I can hear the pump running when I turn the key partially. The exhaust tip isn’t black or smoking, but there is a more than normal fuel smell in the exhaust. The truck side connection seemed fine, but I will raise the bed again when I heal up (tore an intercostal muscle) to check the ground wire. I haven’t been able to check the injectors yet, but they seemed fine before replacing the pump and sender. I’m trying to upload a video of it running

Here is the link for the video