I have changed the fuel pump, carburetor, EGR valve, pcv valve, cap, rotor, spark plugs, plug wires, checked the catalytic converter (OK) Set ignition timing, tried using a fuel pressure regulator, (no change) replaced all vacuum lines, checked heat riser (OK) and replaced coil. No change.
Here's the story, I purchased this truck from a guy who says the original engine (86 4.9L) gave up so he bought a used 1996 4.9L and replaced it. Since the 1996 was fuel injected he changed out the intake and exhaust manifolds to keep the carb so all connections, including the ECU would all work properly and have no issues with the emissions check. He put an in line electric fuel pump mounted on the frame rail because the 1996 engine has no place for a manual pump. I took the truck for a test drive and it ran fine. I made the purchase and before I got it home (about 15 miles) the truck began to sputter and belch out black smoke. I replaced the carburetor and the truck ran great, better than it did on the test drive, but only for two days and then I had the same problem. My first suspicion was too much fuel pressure so I tried an in line fuel pressure regulator installed between the fuel pump and the carb. No change, still running rich. So I purchased a Mr Gasket in line electric fuel pump, made for carburetors with only 4-7 lbs of pressure. Still no change. I then replaced all the parts and made adjustments as listed above but have had no success with the fuel delivery problem. I am 53 years old and have alwys done my own mechanic work. I have built high performance carbureted and fuel injected engines and have owned hot rods most of my life. I am stumped. I have even contacted local repair shops with the problem and they have said they would have done everything I have done and have no ideas where to go next.
I am hoping someone out there has had the same problem and has a fix for me. HELP!!!!!
Here's the story, I purchased this truck from a guy who says the original engine (86 4.9L) gave up so he bought a used 1996 4.9L and replaced it. Since the 1996 was fuel injected he changed out the intake and exhaust manifolds to keep the carb so all connections, including the ECU would all work properly and have no issues with the emissions check. He put an in line electric fuel pump mounted on the frame rail because the 1996 engine has no place for a manual pump. I took the truck for a test drive and it ran fine. I made the purchase and before I got it home (about 15 miles) the truck began to sputter and belch out black smoke. I replaced the carburetor and the truck ran great, better than it did on the test drive, but only for two days and then I had the same problem. My first suspicion was too much fuel pressure so I tried an in line fuel pressure regulator installed between the fuel pump and the carb. No change, still running rich. So I purchased a Mr Gasket in line electric fuel pump, made for carburetors with only 4-7 lbs of pressure. Still no change. I then replaced all the parts and made adjustments as listed above but have had no success with the fuel delivery problem. I am 53 years old and have alwys done my own mechanic work. I have built high performance carbureted and fuel injected engines and have owned hot rods most of my life. I am stumped. I have even contacted local repair shops with the problem and they have said they would have done everything I have done and have no ideas where to go next.
I am hoping someone out there has had the same problem and has a fix for me. HELP!!!!!