Hi, I am new to the site but was referred here by a friend. I am not a mechanic but I think I can do better than the last mechanic that worked on my truck..... I have a 1986 Ford F250, Automatic,460 motor 159000mi, Brand new Edlebrock 1406 series 4 brl carb, New rear fuel pump, all smog stuff removed. This truck runs great while warming up, then when I have driven it for a bit ( 20 min) it starts to idle rough, stumbles, sputters, have to pump it a little to pull off the line, but raise the rpms and it seems fine until you let off the gas again. It seems to run fine on the freeway at 70 but the let off the gas to stop and it will stumble, sputter and sometimes die. I just spent $1600 at a mechanic but it came back more damaged than it went in. It has one of those fuel pressure regulators in a metal line and the line has been cut because they thought it was a fuel filter. They took the tubes off the sides of the motor as it was part of the smog equipment and just crimped the tubes. How can I start tracking this running/stumbling problem and fix it. I have been told timing but wouldn't it cause a consistent problem? I have been told EGR valve??? Any other ideas? Thanks

 

If you are using the stock electric fuel pump, it may have too much pressure for the edelbrock carb, especially if you are not using the return fuel system they used on the stock carb. How hard would it be for you to check the fuel pressure? Can you tee a guage into a rubber line somewhere? You should have 4 to 5 pounds of pressure. You can run a higher pressure, but you may need to reset the float level inside the carb.