Hi all. I need some help before I go crazy- er!
Have a 1993 572A engine (GM 350 Cu in. with a 2 bbl carb. The engine runs great. But after getting it up on plane and going WOT for 3 minutes it starts to backfire violently. It also surges about 200 rpm at 4000 rpm setting. I have replaced all plugs, ignition coil, ignition module, plug wires, anti siphon valve, and fuel water separator. I checked the timing (8 deg BTC), fuel pick up screen, carb fuel filters (screens) and lines. There are no leaks. It purrs at idle and any setting below 3500 rpm. Any clues before I replace the fuel pump and then the carb?
Have a 1993 572A engine (GM 350 Cu in. with a 2 bbl carb. The engine runs great. But after getting it up on plane and going WOT for 3 minutes it starts to backfire violently. It also surges about 200 rpm at 4000 rpm setting. I have replaced all plugs, ignition coil, ignition module, plug wires, anti siphon valve, and fuel water separator. I checked the timing (8 deg BTC), fuel pick up screen, carb fuel filters (screens) and lines. There are no leaks. It purrs at idle and any setting below 3500 rpm. Any clues before I replace the fuel pump and then the carb?