<VV> Fuel Pumps????

[Tony Underwood]

At 12:57 hours 04/26/2005, billpat at telusplanet.net wrote:

>Hey Guys,
>Lots of great discussion on 'good fuel pumps',  and 'bad fuel pumps',
>but I can't recall seeing a description of how you tell them apart. Are we
>looking for a serial number? a style? a color? a manufactuerers name? Might
>need one on my '63 or '66 some day.
>Bill



I posted a way to check these pumps a while back.


The problems with the bogus pumps was that they were manufactured with a 
diaphragm material which not only was not fiber reinforced, it tended to 
deteriorate when exposed to some additives in gasoline, causing it to 
split/tear, which depending on which diaphragm  actually failed could cause 
fuel to spurt out of the vent hole on the pump or drain into the crankcase.

At least two different manufacturers bought into this diaphragm material 
routine, from a gasket material source which assured their customers that 
this material was strong and would hold up and did not require fiber 
reinforcement.   They were wrong.

Not only did this material end up in Corvair fuel pumps, but a variety of 
other pumps as well, causing a lot of trouble in the parts industry and of 
course a lot of failed pumps and crankcases filled with gasoline.   Even 
Cadillac pumps got this material for a short while, know somebody who had 
one fail.   Likewise, Fiat pumps reman'ed here stateside got the bogus 
material and *they* failed as well.    And of course, some replacement 
Corvair pumps also got this bogus material and they would fail after a 
short time.

The reputable vendors have by now likely weeded out most off the bogus 
pumps.    However, some FLAPS have not, and a few stores still have some 
bogus pumps on the warehouse shelves.   Check the pump before you buy it!


The good pumps will have fiber reinforced diaphragm material.   The bogus 
pumps will have what appears to be pure rubber material with NO fiber 
reinforcement.  If the pump has this diaphragm material, do NOT buy 
it.   It *will* leak sooner or later.


To identify the good from the bad, look closely at the sides of the 
pump.   A magnifier will help if there's any question.   A good pump will 
show fibers in the edges of the three diaphragms in the pump 
assembly.   The bogus pumps will show no such fiber reinforcement in the 
edges of the diaphragms.

Look closely.   I've seen some pumps with reinforced diaphragms in one or 
two spots, only to have the third diaphragm made of the bogus 
material.   Make SURE that ALL diaphragms are fiber reinforced.

Also remember that the top screws should be snugged up when the pump is 
installed.   They will also need another snug-up after a couple or three 
days of running time since the diaphragm material will "settle in" and the 
screws will likely need a touch-up after a while.    Then after about a 
couple of weeks, check them again.


I have close-up comparison photos of a good pump and a bogus pump side by 
side somewhere on the other computer... if anyone wants the image I'll go 
dig it up.    Or, maybe someone in here still has it handy; I sent it to a 
few people before.

Knowing the difference between a good pump and a bogus pump can save you a 
LOT of trouble.



tony..