Another Fuel Pump Humming

[Kneale Brownson]

  I believe the check valve mounted to the top of the fuel pump serves to 
regulate the fuel line pressure.  I'd think its failure would result in 
fuel pressure-related engine operation problems rather than increased 
buzzing from the pump.  There is a history of pump buzzing related to a 
partially plugged screen in the bottom of the pump, often plugged from an 
anticorrosion lining in the fuel tank that possibly gets attacked/detached 
by changes in gasoline formulations.  The fix for that has been to pull the 
pump and remove the screen.  The filters between the tank and the fuel 
distribution system supposedly take care of anything the pump screen would 
have filtered out.


At 11:06 AM 04/13/2001 -0400, Michael A. Carr wrote:

>Hey People,
>
>My Fuel pump has been hummin for quite a while, ( 85 5000cs stick, non 
>Turbo non Quattro ) I just checked with the local Audi dealer, as an 
>excuse really to see the girl at the parts desk ( she's got
>a boy friend tho :-(, but she is really engaging none the less, so it's 
>nice to see her now & then ).........ANYway they wanted $$$360 sumthin, 
>BUT they said something VERY interesting that made me
>wonder what our bunch knows about this aspect (if it is a viable aspect)
>
>Wut they said is you can buy the check vavle for the pump seperately; but 
>you can't buy the pump w/o the check valve, reason "by the time the pump 
>goes, it's definately time to change the check
>valve"
>
>You can tell where I'm going with this right?
>
>Does anyone KNOW whether the dreaded humm is caused by the pump, or is 
>there a misers chance that the check valve might be the cause, at least in 
>some instances? And ofcourse how to go about
>verifying .....Any BTDT's on this would be appreciated.
>
>Michael
>
>