Check valves on mechanical fuel pump // anti siphon ???

[wellcraft-classic210]

Anyone know the details on the mechanical fuel pump check valve design on a 1983 5.7 Mercruiser / Alpha

as in ---Metal to metal or metal on rubber etc

Just wondering -- Should they be able prevent fuel from siphoning back to the tank over an extended period such as a few weeks ?

 

[Bondo]

Ayuh,...... There's 2 check valves in the pump, 'n 1 at the tank,......

fuel can't drain back into the tank,....

 

[wellcraft-classic210]

OK mine must be worn out as that's whats happening /// Thanks!!!

 

[Scott Danforth]

or your welsh plugs in the carb are leaking

 

[wellcraft-classic210]

I Just sealed the plugs and noticing the line still empties out as it has for the past 3 years // Also had a recent low pressure at start incident after a few weeks with no usage. That cleared with some fuel poured into the intake

-- Might have been backwash & debris from the filter getting into the fuel pump check valves // It ran fine afterwards for 2 days with many restarts & over 4 hours run time

I did empty and replace the fuel filter during the incident & saw a fair amount of small particles in the fuel from the old filter.

-- So I am trying to figure out if the check valves in the fuel pump are leaking and allowing back flow & occasionally pull a piece of dirt in the check valve and cause low pressure that can clear with a fuel dump into the carb.

Trying to use logic but also thinking at around $75 it might be good preventive maintenance for what appears to be the original 1983 pump.