<VV> Fuel Pump

[Jim Burkhard]

The car "still running" doesn't mean it's not time to S&#%-can the pump.

When the starts to die, you can wind up with:
1. A leaky diaphragm causing fuel leaking EXTERNALLY from the pump 
(fire hazard) onto the engine. thi smight start out as a very slight 
weepage around the edge of the pump of screw holes, so be sure to keep 
your eyes peeled for such telltales.
2. A leaky diaphragm causing fuel to leak INTERNALLY into the 
crankcase, diluting the oil.  This *might* (depending on whether fuel 
leakage or oil consumption is higher) manifest itself as the dipstick 
level getting higher the more the vehicle is driven drive it.  Or, you 
might not notice an increase in level, but the oil might smell really 
fuel-ish.  Either way, it's bad for the engine because your oil isn't 
lubricating nearly as well as it should be.
3. It's probably also possible that you could have NO leaks, but the 
checkvalving in the pump cease to work well. This would result in 
normal engine operation under low load, but an inability of the pump 
to "keep up" with demand under high fuel flow conditions. I'm not sure 
if this is a common failure mode for Vairs (the other 2 are), but by 
nature of the design mechanization, it should be possible.

Jim Burkhard

Chris C wrote:
> I know stupid question.
> 
> What are the signs of a failing manual pump?  The car runs so it has not 
> failed.