Dan12valve
Newbie
So I've been lurking for a while, but that's for an intro later.
I have a 94 c1500 5.7 auto 2wd 4.10 gears and a g80. My commute is roughly 75 miles one way through the highways and hills of Tennessee, thus my problem.
Recently a series of things have started acting weird. It started loosing power when climbing and would all of a sudden gain power like a switch was flipped without changing gear. So traced that to being caused be the egr system. The valve functions correctly so unhooked and blocked the vac line to it. It ran much better for several weeks.
Then it started loosing power again but only above 3000. All the sensors check out. Check engine light would come on when it would periodically have the chance enter it's self check on account of the egr. Light on or off performance is the same. At one point running non ethanol helped minutely but the lack of power was still there.
Tonight I finally ran fuel pressure test. Was ~10psi wot and traced to the fuel pump. So when ahead and rebuild tbi and replaced fuel pump. Took it for a test drive and the first accel test it was much improved in 1st gear, normally it would only rev to about 3200 wot and bog out. This time it went to 4 without much issue and hung for a moment then shifted. The second run it was back to its old 3200 at wot and started bogging.
Short of the computer, injectors, or mechanical issue, I can't figure it out. Replaced coil, fuel pump, plugs wires and cap have 3000 miles on em, map, o2 about 5000 miles ago. Checked iac, tps, map, and egr sol. Truck gets about 14.9 mpg. I remember it used to be closer to 17 or so. Injectors appear to have good spray pattern and cycle very strongly. Idle has always been a tiny bit rough but only just enough to feel.
Either it's running out or fuel or spark. Not sure which or why. Sry for long windedness.
I have a 94 c1500 5.7 auto 2wd 4.10 gears and a g80. My commute is roughly 75 miles one way through the highways and hills of Tennessee, thus my problem.
Recently a series of things have started acting weird. It started loosing power when climbing and would all of a sudden gain power like a switch was flipped without changing gear. So traced that to being caused be the egr system. The valve functions correctly so unhooked and blocked the vac line to it. It ran much better for several weeks.
Then it started loosing power again but only above 3000. All the sensors check out. Check engine light would come on when it would periodically have the chance enter it's self check on account of the egr. Light on or off performance is the same. At one point running non ethanol helped minutely but the lack of power was still there.
Tonight I finally ran fuel pressure test. Was ~10psi wot and traced to the fuel pump. So when ahead and rebuild tbi and replaced fuel pump. Took it for a test drive and the first accel test it was much improved in 1st gear, normally it would only rev to about 3200 wot and bog out. This time it went to 4 without much issue and hung for a moment then shifted. The second run it was back to its old 3200 at wot and started bogging.
Short of the computer, injectors, or mechanical issue, I can't figure it out. Replaced coil, fuel pump, plugs wires and cap have 3000 miles on em, map, o2 about 5000 miles ago. Checked iac, tps, map, and egr sol. Truck gets about 14.9 mpg. I remember it used to be closer to 17 or so. Injectors appear to have good spray pattern and cycle very strongly. Idle has always been a tiny bit rough but only just enough to feel.
Either it's running out or fuel or spark. Not sure which or why. Sry for long windedness.
