fuel pump eccentric

My D-100 had a similar problem, plus after sitting for a few days it did not want to pull fuel up to the carb while cranking (had to manually prime the carb. Turned out to be a very small leak in the fuel line. Would not leak fuel, but would suck air, and the pump would not pull enough fuel. Did not locate the leak. I just replaced the complete fuel line from the tank to the fuel pump.

My 88 diplomat with a 318 had a problem after I replaced a oem pump (broken arm) with a replacement. Car would run ok, untill trying to pass someone on the highway. Then it would run out of fuel just as I got along side of them. Turned out the replacement pump had too much free play in the arm before it would operate the diaphragm. Would not pump enough volume. Every pump I got, even from different stores was the same. I wound up heating the arm and bending it slightly, to take up some of the free movement. That worked good enough. About 2 years later, I got another parts store pump, and it did not have the excessive free play. So installed that pump, and car has been fine, since.