Fuel pump question

[John Straub]

Any idea, why a Bendix pump on my '67 would run full on at idle and not slow down. The floats seem OK.

Thanks,
John

[304065]

You know how when you turn the pump on it goes thumpthumpthump thumpthump thump thump thump thump thump etc

So the solenoid wants to slide back and forth at a fixed rate which is a function of the metal slug, magnet and the breaker.

When there is LOW pressure on the outlet side the pump moves quickly to pressurize the system. When the pressure builds the pump slows down.

So there is either an internal leak in the pump causing pressure to bypass (torn diaphragm), a leaking float (as you identify above) or a leaking fuel filter or line. There are no other explanations.

Check everything! Is it a real Bendix or the Facet replacement?

[John Straub]

It's a Facet replacement, John. The car also floods at idle and the engine wants to bog down when this happens, but the floats seem ok... And it doesn't happen every time....Sometimes it slows down.

Thanks,
John

[chris_seven]

If the needle valve is worn then you can have a condition which allows fuel to enter the reservoir even if the float is operating correctly.

Bendix pumps always give maximum delivery at zero pressure and zero delivery at their maximum pressure so, as has been said, the faster the pump operates the lower the line pressure and if the float is working correctly the needle valve would be a good suspect in light of the other symptoms.