The HP pump you're working with and the later LCS (square body) pump
have just one valve. The two HP pumps I have (points and electronic)
both have two valve discs (p/n 29 on the parts diagram on the SU carb
site that Alan sent). One is in the top of the valve body (p/n 33) held
in with a bent wire spring (p/n 32) - delivery valve. The other sits
below the valve body - suction valve. I don't understand why your pump
only has one disc.
The period workshop manual I have states that the pump should go at
least 15 seconds between pumps when dead headed.
See the fault diagnostics on page 78 of the SU Carb Manual on John Sim's
site for some additional info:
How it works (I had a pump apart): When the coil is energized, the
diaphragm (p/n 1) moves away from the pump body - the suction stroke.
The top valve disc gets sucked down and that blocks the line to the
carbs. Fuel gets sucked from the fuel tank, through the filter and the
valve body, and into the chamber formed by the diaphragm and the round
aluminum body piece (p/n 39). When the rocker/points assembly throws
over, the coil is de-energized. The spring (p/n 3) pushes the diaphragm
back pushing the fuel back into the valve body. The pressure forces the
lower valve disc to seal against its seat and the upper disc to move
away from its seat, pushing the fuel towards the carbs.
3000 MkI Registrar
Bob Spidell wrote:
> Yep, except we have electronics instead of points. Note only one valve.
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