<VV> Fuel Pump failures

[Tony Underwood]

At 02:29 hours 09/11/2005, Brown, David wrote:
>Steven,
>I can almost guarantee that the pump surfaces are warped.


This *can* happen now and again, depending on who actually made the 
pump.   Seems a number of people along the way were contracting pumps 
and the castings varied to a rather wide degree.   I spent some 
considerable time just last weekend talking to John Moody about 
rebuilding pumps and we discussed the variations in housing castings 
along with the *bogus diaphragm material* that was what started all 
this "mechanical pump = bad" hype that still persists to this day.


>I started
>about a year ago rebuilding my fuel pumps (plus several for others in
>our club) just because I like to run original stuff.  I have done 6 & no
>problems so far.  Interestingly, in EVERY case the diaphragms were FINE,
>but the surfaces were warped.


I do have a collection of diaphragms which were obviously cracked 
through to the fiber reinforcement, no doubt the 40 + years of 
service will do this sort of thing to any pump.   I don't know how 
many fuel pumps I do have (a lot) but I intend to either part them 
out and/or rebuild the ones I have because I also agree that the 
original AC/Delco pumps were a good design which will last as long as 
the engine itself in many cases and are likely candidates to rebuild.


Now, whether or not you can get kits to do this is one thing; 
"rolling your own" rebuild kits is another.   I have diaphragm 
material available which works out well for fuel pumps (kevlar fiber 
reinforced viton sheet) which was originally intended to be used in 
chemical pumps, so I don't have much fear of its working out in fuel 
pumps (and to date no problems).   This stuff is expensive and I 
don't have much left so I'm hoarding it now... ;)   But personally 
*I* would like to know where to find rebuild kits for existing 
pumps.   I presently have ONE, and that's it.   The other rebuilds I 
fool with have to be done with cobbled homebrew diaphragms, not an 
easy trick.

NOW:   There is a method to this madness.

The original style pumps GM put on the engines were made from good 
castings.    You seldom see one of these types of pumps ever 
warping... they're identified by weight since those good castings are 
heavy.   It's my opinion that a later vintage lighter casting New 
pump is not necessarily superior to an original casting which has 
been correctly rebuilt.   So, the logic of rebuilding an original vs 
buying new does have merit... IF you can find the parts to rebuild 
the pump and know how to do so.


Again:  There ARE still some bogus pumps in the system, fitted with 
those non-reinforced diaphragms which WILL fail in relatively short 
order, warps notwithstanding.

IF you buy a new pump from anyone outside of the reputable vendors, 
CHECK IT!    Look at the diaphragm material  along the sides of the 
pump.   Make SURE it's fiber reinforced.   You CAN see the fibers in 
the good pumps by careful examination.   Take a pocket magnifier with 
you if there's any doubt.   Before you go pump shopping, take a close 
look (if practical) at a known "good" (not necessarily operational) 
design pump and note the fiber reinforced diaphragms with their plies 
of cloth, visible on the  edges of the diaphragms sticking outside 
the outer radius of the pump body.

If the pump you want to  buy doesn't have this fiber reinforcement, 
DO NOT BUY IT.  It's as simple as that.  Just don't buy the damned 
thing because it's gonna fail regardless of how pretty it looks.

Nearly EVERY pump I've seen that failed quickly for the last 5-6 
years has been built with this bogus diaphragm  material.    This 
doesn't include pumps with top cover screws that were never 
re-tightened as per recommendations or pumps which had valves stick 
open because of fuel tank debris in the pump etc.   I'm talking about 
catastrophic failure where fuel exists the side of the pump onto the 
ground or gets dumped into the crankcase.

On the other hand, NONE of the pumps I've bought or used etc that had 
the fiber reinforcement have shown ANY problems at all outside the 
standard "tighten the screws after a couple days or so" routine, 
except for ONE which had a valve come loose because it hadn't been 
staked into place properly, restaked it and it's still running today 
after 5 years (in the red ragtop).   And that one was a fluke, not 
likely to be a common problem.

Again, I have absolutely NO fear of the mechanical pumps nor do I 
have any issues with driving a Vair anywhere with such a pump IF it's 
the RIGHT pump.


SO, folks, when you go shopping for a fuel pump, make sure the one 
you buy IS the RIGHT pump.   CHECK IT.   Good grief, it's not 
hard.   These correct original pumps lasted for 30-40 years in some 
instances...  so don't anybody tell me they're a bad design.   ;)

This doesn't mean that every mechanical fuel pump is gonna last 4 
decades, but it does show that they sometimes can.    Again, I'm not 
afraid of mechanical pumps.

>As instructed by the folks I get the kits
>from, I file the surfaces flat using a large file.  The worst one to
>date was the "newest" one.  It was brand new, but the original vendor
>box had been lost, so I don't know where it came from.  It was my only
>spare at the time & I had been carrying it since I bought my car (6
>years ago).


Bad omen.     That was about the time all those problem pumps were 
flooding the market.

Whoever was manufacturing (or remanufacturing) these pumps wasn't 
doing it as well as they should.   I'd not be surprised to see warped 
castings, too.


[mailto:virtualvairs-bounces at corvair.org] On Behalf Of Steven J.
>Serenska
>Sent: Sunday, September 11, 2005 3:46 PM
>Subject: <VV> But Seriously Folks, Here's a Post About Fuel Pumps
>
>VVers:
>
>I replaced the fuel pump on my '65 less than 2K miles ago (i..e, last
>summer).  This morning, while warming it up, I noticed a small puddle
>forming under the engine.  When I opened the hood, fuel was leaking
>quite rapidly from the side of the pump.  I tried tightening all the
>bolts on top of the unit, but the leak continued.


CLASSIC failed diaphragm.   Now, sometimes this can also be caused by 
the wrong pump (60-61 series pumps have different length pump rods) 
on the wrong engine.   If you put an early-early pump on a later 
series engine without also changing the pump rod, it's possible to 
overstretch the diaphragms and tear them or stretch them to the point 
that they leak around the area where the diaphragms are secured to 
the pump pushrod.   This usually results in the pump spilling fuel 
down the housing into the crankcase although later pumps included an 
upgrade with an internal collar or "dam" to help prevent this should 
the pump suffer internal leaks, thus spilling fuel out the vent hole 
in the side of the pump instead of its spilling down the inside of 
the casting to wash the crankshaft eccentric.

The modern day trick is to replace the pump rod on early earlies with 
the late pump rod and the late fuel pump and make it "universal" but 
many folks want their originality to remain, thus there still being 
two different pumps etc.   (my '60 has not only its original pump 
rod, but it still has its ORIGINAL pump, or at least the original 
style pump that was on it when I got the car decades ago which even 
then looked like it had never been off the engine)


>I don't mean to re-start the debate about mechanical vs. electric pumps.
>I just want to replace my mechanical unit and get driving again.
>
>I have read here on VV about how there used to be a problem with the
>fuel pumps, but now the problem's gone,


NO it is NOT.  Not yet, anyway.   Those bogus pumps remain sitting on 
FLAPS shelves as we speak.   Not long ago, a pump purchased from 
NAPA, gold and black box, was brought to me by a fellow to check out, 
was gonna keep it on hand as a spare etc and it was the bogus 
pump.   I told him to take it back; he did, then bought a pump from a 
vendor which was fine.    Another fellow had a pump fail a few years 
ago on the way back from a show... I gave him my spare to get him 
home.   He replaced it with a new pump purchased locally and even 
delivered it to my door...   you guessed it, the pump was one of the 
bogus items.   I kept it anyway, use it to show locals the 
differences between good pumps and bogus pumps.   Hell, it might 
still be good as an emergency pump to carry around etc, likely would 
last long enough to get somebody home but I'd not trust it any 
farther than that.     It remains on a shelf.

For what it's worth, all the pumps I've checked out at the major 
vendors for the last few years have all been the good pumps.   This 
doesn't mean that a pump might not sneak by with a problem etc but 
the ones I've seen have looked good.


>and to look for the diaphragm
>with the cloth fibers, and etc., etc., etc.  Unfortunately, I bought the
>pump I did with an assurance from the vendor that it wasn't from the old
>stock and that the problem has been taken care of, and that the
>diaphragms had the right reinforcing materials, etc., etc.
>
>Despite such assurances from the vendor, I couldn't take my car on a
>long-planned trip on this crystal clear late-Summer day today.  So, yes,
>I'm disappointed, and kind of annoyed.


Check the pump.   Pull the top off and check the diaphragms for tears 
or splits.   If it's a bogus pump that slipped by the vendor I'll bet 
they're gonna be quick to make it good.


>Clarks currently lists pumps from two vendors, one from a vendor Clark's
>believes has fixed the problem


I spoke to them at a show a few years ago and pointed out the problem 
area with a pump they had on hand at the time which *Was* one of the 
bogus pumps.   They seem to have been quick about weeding these pumps 
out and the ones I've seen lately have looked good.   Likewise the 
ones from Underground.   The Source pumps have been fine as well.

It may well have been the luck of the draw, and you managed to get 
one that slipped through the cracks.   So far, this seems to be less 
and less of a problem as the bad pumps get weeded out of the system.


>and another from a vendor with whom they
>have had less experience.  (The full discussion is at
>http://www.corvair.com/user-cgi/catalog.cgi?function=goto&catalog=MAIN&s
>ection=MAIN&page=65).

This demonstrated that they were aware of the bogus pump issues and 
were taking steps.


>Corvair Underground indicates that the pumps they carry have had the
>problem fixed.  The Source indicates their pumps are guaranteed.


Both these vendors guarantee their pumps.   They both sell good 
stuff.    In fact, it's my understanding that all the major vendors 
guarantee their fuel pumps.


>Can anyone tell me (online, or offline if you want to trash someone)
>which pumps they have had *success* with?

Perhaps the vendors in question might wanna address your concerns and 
assure you as to the quality of their products.


>BTW, if this has been discussed to death over the past few months,
>please forgive me as I have been offline.  If that's the case, let me
>know and I'll go read it in the archives.




Others' opinions may vary, but if it involves something we all might 
learn something from, I don't think that it's something which has 
been "discussed to death" yet.


Meanwhile, pop the top off that pump and find out just what did fail, 
and post what you find.   I'm curious to see what went wrong myself.


tony..




PS:     For some interesting insights on Corvair fuel pumps, read the 
articles written by John Moody in the Corvair Tech 
Guide.    Interesting stuff.