mulitple things to consider. fuelline rusting (growing shut) , something
foregin in the tank be it dirt or something amazing like a cloth of some
type(over and over this has been found!) fouling the pick up tube.
hopefully you installed a filter either between tank and pump or at least
before the carb. if there is dirt(and unfortunately there usually is after
all this time!) you do not want it finding the carb! it would be nice if
it did not find the pump either! also depending upon the type of pump,
there may be a screen on the inlet side before the valve in the pump. all
of the copies of the old AC "tick-tick" type pumps (fawcet, AC, stewart
warner, and a bunch of others make or made copies of this pump!) have a
strainer inside the top plate of the pump held in place with 4 screws.
what you are describing sounds like a fuel delivery problem related to
improper flow to the pump of from it. most pumps either work, or they do
not. the old AC types have an acordian diaphram in them wich when torn
still work a tiny-tiny bit but are rather useless at that stage.
i have had this happen over and over with old cars that seem to be ready to
roll! dirt sucks up over a short time and cloggs the strainer or filter.
you shut it off and the fuel draining back to the tank carries away some
dirt away from the filtration device revealing "some" available area in the
filter again. you start it up, and over a short time the pump sucks back
up enough dirt to once again clog the filter. but running sitting still
there is little load for the pump to do idling away. out on the road the
pump will work very hard playing "keep up" with the used fuel at speed(when
demand increases the restriction usually becomes a real problem!
(fuel-us...lackus results in funky-us runus!) look for the source of
restriction (crimped line from running something over or a careless mechanic
nicking it with an engine or trans installation) , a dirty filter or
restricted pick up tube first! do not assume it's the pump right away.
trouble shoot the problem before you spend any money. it may be the pump
but be certain of that first.
chuck.
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