[TR] Leaking fuel pump or not?

[Geo Hahn]

Not raining here, if fact it's a beautiful day with our first annual
'100 miles/100 degrees' event taking off at 1:00.

I'll offer some comment based on my experience with the TR3/4 pump --
physically different but functionally similar I think.

On 8/16/09, Ron L'Herault <lherault at bu.edu> wrote:
> Maybe its raining somewhere...
>
> 1. If the diaphragm were leaking, one should smell gas on the engine side of
> the pump, right?

I would suppose so though the smell of petrol is so pervasive that I
am not sure that is a useful test.

> 2.  If the diaphragm were bad, and you apply lung pressure to the inlet
> side, would you hear or feel a pressure drop/leak?

Yes I believe you would, provided you have blocked the outlet and
provided that the leak is large enough.

FWIW - on a pump with a good diaphragm & check valves you should be
able to blow on the outlet and the inlet check valve will close and
hold the pressure.  You should also be able to suck on the inlet and
the outlet check valve will close and hold the vacuum.

> 3.  If you applied lung pressure to the outlet side and the diaphragm were
> bad, would one be able to get the cam to move?

No.  For one thing, the check valve will stop the air flow before
anything happens.  In theory blowing on the inlet (with the outlet
blocked) might be the set-up for this but the amount of air pressure
needed to move operating lever (if that is what you mean by cam) would
seem to me to be a LOT more than lungs could provide.

Geo