| Install fuel pump [message #180826] |
Sun, 19 August 2012 15:36  |
Nanuck
Messages: 3
Registered: August 2012
Karma: 0
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Good afternoon! Just found the forum and looking for advice. Newer gmc'r since 2011 with a 1978 Royale (love it). Had some power loss on last trip and had to replace my inline electric fuel pump (455 and mechanical pump removed prior owner). Club members told me they are using carter 4070 so I got one and thought I should pull the smaller napa pump I just purchased (both are rated 5). My current pump has two wires, no ground. The carter is dc pump with one hot and one ground. Have others made this conversion? Thanks for any help!
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| Re: Install fuel pump [message #180846 is a reply to message #180842] |
Sun, 19 August 2012 18:16  |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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I would connect the ground wire that came with the 4070, directly to the frame.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Install fuel pump [message #180857 is a reply to message #180826] |
Sun, 19 August 2012 19:24 |
zhagrieb
Messages: 676
Registered: August 2009
Location: Portland Oregon
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A couple of thoughts on your new Carter.
Don't know where the present one is located but I'd put the new one as close to the tanks as possible. Less chance of vapor lock that way.
In home wiring the black wire is "hot". In automotive black is USUALLY ground. Be sure which is which in your install.
I take exception to wiring the fuel pump through an oil pressure switch. Do that and a drop in oil pressure will kill the engine. Good for the engine but bad for you if you're in traffic in the third lane doing 65. If you're concerned, better to wire a pressure switch to a loud horn and keep the engine running long enough to get out of harms way.
Glenn
Glenn Giere, Portland OR, K7GAG
'73 "Moby the Motorhome" 26'
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| Re: [GMCnet] Install fuel pump [message #180862 is a reply to message #180857] |
Sun, 19 August 2012 19:36 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Glenn,
The purpose of the oil pressure switch is not to protect the engine. It's
to ensure that fuel flow stops when the engine stops -- especially in case
of a fire. There are other ways to achieve that objective, of course.
Some power the fuel pump from the alternator output (the center terminal
on the isolator) since the alternator quits producing when the engine quits
rotating. But with a combiner, that doesn't work because the alternator is
connected directly to a battery.
It seems to me very unlikely that an oil pressure switch will spontaneously
open while in operation. My experience has repeatedly been that they will
fail to close at start-up.
I do know specifically of one freshly rebuilt Cad500 engine which was saved
from destruction by the oil pressure switch opening when the oil pump
failed. Not in bumper-to-bumper high speed traffic though.
My answer to your scenario is to stay out of that kind of traffic. :-)
Ken H.
On Sun, Aug 19, 2012 at 8:24 PM, Glenn Giere wrote:
> ...
> I take exception to wiring the fuel pump through an oil pressure switch.
> Do that and a drop in oil pressure will kill the engine. Good for the
> engine but bad for you if you're in traffic in the third lane doing 65. If
> you're concerned, better to wire a pressure switch to a loud horn and keep
> the engine running long enough to get out of harms way.
>
>
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Ken Henderson
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www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Install fuel pump [message #180872 is a reply to message #180866] |
Sun, 19 August 2012 20:33 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Chuck,
Some of us have found it useful to install a prime push button to allow the
fuel pump to run before starting. That's especially handy if your intake
manifold exhaust crossover has not been sealed -- after shutdown the hot
manifold will cause the fuel to evaporate from the fuel bowl, slowing the
next start.
Then there are those who prefer to crank for a while so the engine's well
lubricated before it starts.
Ken H.
On Sun, Aug 19, 2012 at 9:18 PM, Chuck Holden
<chuck.holden@anoka.k12.mn.us>wrote:
>
>
> Thanks guys. My pump is located close to tanks, with filters prior,
> selector switch still intact. I think location is good and I will trace
> wiring this week. Might already be an alternator or some shut off, as it
> seems to take a bit to get fuel to carb (still caburated) even when key is
> on prior to start. From all the responses it's obvious I need to verify
> that power to pump shuts off...big help!
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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