In the last 1000 miles I have gone thru 2 mechanical fuel pumps. I'm using the Airtex 4149. What seems to be happening is for some reason the pump arm that rides on the lobe seems to get stuck in and only returns out a fraction of the way. When the pumps were new the arm would fully extend allowing a full compression stroke and full return stroke to properly pump. If I let it sit for a while the arm seems to pop back out to its full outward position. even with all the lines disconnected and pumping it by hand it will still not fully return outward all the time. Was I lucky enough to get 2 bad pumps?
Fuel Pump Failures No ; This usually indicates you're using the wrong pump . Match the arm's bend and length against a known proper pump for your engine . I went through this crossing America in an old IHC School Bus towing a two axle trailer with an MG TD on it ~ IIRC I went through two or three pumps because the Partshaus' along the way didn't ever have a proper IHC 345 V-8 pump and it'd last a day or two then break again in another state . Some of the trip was made using gallon jugs of gasoline lashed to the top of the West Coaster mirrors...... I wasn't pleased to say the least . As long as the flange and operating arm are identical the exterior form isn't important as long as nothing touches (frame , headers etc.) . Keep us posted , consider an electric pump as they're cheap and reliable *if* you choose the correct 2 ~ 4 PSI one instead of getting sduckerd into using a higher pressure one with a pressure regulator . If you're in Farm Country , look at old threshers, tractors , gen sets and so on , they often have good if filthy 12 volt American made E - Pumps that simply never quit .
