Rough Idle

Posted by steve828 On 2011/5/5 15:33:18

I installed a rebuilt AC fuel pump with new material (neoprene) diaphragms in my 1954 Packard Super Clipper 327ci L-head 165hp 8cyl. The old rubber diaphragms in the original fuel pump were deteriorated. The engine idled roughly with the old fuel pump and it still idles roughly and occasionally stalls in traffic when I release the accelerator pedal and use brakes to stop. I have played with the idle adjustment screw and that does not seem to help much. I have noticed that the flexible fuel input line to the pump seems slightly worn and brittle with age. Might this be the culprit or is there something else in play, perhaps involving the carburetor? Thanks for your thoughts.