The standard test of a mechanical pump is 1 pint of fuel pumped into a catch can in 30 seconds at idle speed. If the engine won't idle for half a minute from the fuel in the float bowl, you've got other problems. If the pump fails the volume test, you're not done- - - -check for 3-5 PSI of output pressure with at least a few seconds of pressure on the line after shutdown, and 10-15 inches of vacuum on the suction side, also with a few seconds of vacuum held after the engine stops. If the pump passes both pressure and vacuum tests, find the restriction in the line from the pump to the tank, a clogged tank pickup line, or look for an air leak somewhere. The flex line from the frame to the pump can suck air without leaking gas.
Jerry
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