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Re: [GMCnet] Fuel Pump Poll [message #239419 is a reply to message #239417] Mon, 10 February 2014 13:44 Go to previous messageGo to previous message
James Hupy is currently offline  James Hupy   United States
Messages: 6806
Registered: May 2010
Karma:
Senior Member
When we crossed Canada on the GMC Cascaders Rolling Rally, we had failures
on three different coaches with three mechanical fuel pumps, Two were 455s,
and one was 403. Two quit pumping, and one broke the third fuel fitting or
return line fitting where it exits the pump body. Fuel leaks quite badly
when that happens. We quickly exhausted our onboard supply of spare pumps,
and were forced to purchase new ones in Jasper, Canada. We bought 2
mechanical and two Carter 4070 electric pumps. Rang up over $600.00 US
Dollars when all was paid for. But, we fixed all three and continued our
journey without towing bills. NAPA is alive and well in Canada. The
mechanical pumps are a wrestling match in the motor home. Try it in
Pocahontus Campground in the pouring rain with roving bears. Gives a whole
new meaning to the term emergency roadside repair. (Grin) Would not trade
the memories for anything. Part of owning a 40 year old vehicle that gets
used hard and put away wet.
Jim Hupy
Salem, OR
78 GMC Royale 403


On Mon, Feb 10, 2014 at 11:16 AM, Johnny Bridges <jhbridges@ymail.com>wrote:

> I'll sit on the other side. I've not had a problem with the fitted pump.
> I note that mine, like most of the others I've ever seen, has a weep hole
> which will drain fuel in the event of a diaphragm failure. I find that
> feeding the thing the fuel it was designed for keeps it going without lot
> of histrionics, and keeps me - so far - from fixing symptoms. My only
> concern is a fairly regular trip to San Antonio, on which no decent gas is
> available. For thatr one, I drive out on good gas, load it with junk, and
> come home early in the day. This in August, I've had no problems. Comes
> the day no decent gas can be had, I will rethink my position and (probably)
> stick somebody's TBI system on it. Having had good luck with Holley
> elsewhere, it would currently be the weapon of choice, but I'll ask around
> when I get to that point.
>
> --johnny
>
> From: Ken Henderson <hend4800@bellsouth.net>
> To: gmclist <gmclist@temp.gmcnet.org>
> Sent: Monday, February 10, 2014 8:00 AM
> Subject: Re: [GMCnet] Fuel Pump Poll
>
>
> Rob,
>
> Fear of a ruptured mechanical diaphragm is only part of my refusal to pump
> through one.
>
> More important is the question of "why bother?". The benefits from the
> rear-mounted electric pump argue in favor of it alone vs a mechanical pump
> pump alone; it then follows that in case of a failure, I'd rather have
> electrical redundancy than the mechanical pump.
>
> Then there's the question of "why through?". It's trivially more difficult
> to run the electrical pump in parallel with the mechanical pump (using
> check valves), thus completely avoiding questions of pressure drop across
> either of them as well as eliminating the diaphragm rupture question.
>
> The real reason I originally installed the second pump, after deciding that
> I would always have redundancy, was the abominable access to the Olds'
> mechanical pump. It was a real PITA to get to the darned thing. The ease
> of installation and maintenance of the electrical pump was child's play by
> comparison, so when it came time to replace the mechanical, I resolved to
> never fool with one again.
>
> Finally, the elimination of the selector valve eliminated one more recently
> failure-prone item, though mine went on to serve a new owner well.
>
> So, while I was never paranoid about the hazard of diaphragm failure, I
> just find it illogical to retain one.
>
> JMHO,
>
> Ken H.
>
>
>
> On Mon, Feb 10, 2014 at 12:22 AM, Robert Mueller wrote:
>
> > Ken,
> >
> > Naturally I respect your point of view, however, I'll bet JimB has
> > installed lots of these little pumps which put out 1 to 4.75 psi
> > and to date I haven't heard anyone noting their crankcase got pumped full
> > of gas. GeneF noted that he was aware of two engines that
> > got trashed when the owner moved the mechanical fuel pump with a leaking
> > diaphragm from a failed engine to the new engine.
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