Marcos Beltran
OBS Enthusiast
Alright yall i have a weird on here. First let me start with a little history of the truck. Bought a 1996 GMC Sierra V6 Vortec 4.3 liter stepside as a father/son project about a week ago. When i first purchased the truck, threw a battery in and the truck fired right on up after 2 years of sitting. Took it home, changed the oil, did a coolant flush, topped off other fluids, and checked the brakes. All were fine. Drove it around the block( country block) for 2 days and had no issues. Ran fine and was just shaking down the vehicle. So on the 2nd day went to try and put it reverse while the truck was running and could not take it out of park. After messing with it for a few seconds i just turned the truck off and was able to shift the gears again, put in park and tried to turn the truck on but it wouldnt start. Its like it would turn over but wouldnt start. Felt like it wasnt getting fuel. So i go to the fuel filter along the frame rail and disconnect the line and fuel was passing through. Then go to the intake manifold, find the fuel inlet tube, put a rubber hose to it, and put to a jar to catch any fuel that will come out when cranking the engine. So i tell my son to crank the engine and a stream of gas came out. Pump seems to be strong but then the weirdest damn thing happened. The damn engine turned on. Ran perfectly fine. Reconnected the gas line, put the breather back on and it ran fine. No issues at all. After turning if off and on a few times no problem, but on the 5th try if wouldnt start again. Went through this 4 different times and each time it was the same exact thing. It would start after disconnecting the fuel inlet tube, letting a little gas run out, put back together, and crank it up. Then would not start again after five starts. So rented a fuel pressure tester and at first was getting 60 psi but then the truck started acting erratic during idle which made the fuel pressure rise and lower so i figured well damn the pump must be going bad. So replaced the pump, worked really well for like 15 minutes and the problem came back. Now i know it can also be the fuel pressure regulator or injectors causing this issue if there is a leak in the manifold but i cant tell from the fuel pressure test cause of all the fuel psi fluctuating. I have a scanner that i purchased and i should get it today, dont feel like throwing money at it just replacing stuff. Also check engine light wasnt on before i put the new pump in but now it is. The gas doesnt look bad at all and has pit a new fuel filter and fuel strainer at the pump. Also looked down into the tank and there was no debris in it. Was really surprised abiut that. I just find it really strange that truck starts when you disconnect the fuel line and runs fine for a little while but wont start up after turning off the truck a few times. But now its also having acceleration issues like it bogs down sometimes and will barely make it down the block and then 3 minutes later it idles perfectly fine and runs great. Really confused here. Anyones help or suggestions is greatly appreciated.
