If the engine runs smoothly during the few seconds it runs then you have
a fuel problem. It could be a stuck choke as Richard suggests. It could be
a clogged fuel filter (where the fuel line enters the carburetor). It could be
a bad or marginal fuel pump. It could be a partially stuck float valve
(inside the carb - requires rebuild). It could even be clogged fuel lines
back to the gas tank or a clogged pick-up inside the tank. If the engine
does NOT run smoothly then it is most likely an ignition problem. This
could be a bad HEI module (inside the distributor), bad spark advance
system (comes in two flavors - vacuum advance control or a very simple
"computer" control.) If it sputters, luggs, and backfires it is really out of
whack timing.
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