Home » Public Forums » GMCnet » [GMCnet] Good idea to remove a working mecanical fuel pump.
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| Re: [GMCnet] Good idea to remove a working mecanical fuel pump. [message #316080 is a reply to message #316077] |
Sat, 15 April 2017 19:26   |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Bob,
For my part, the only configuration I'd even consider is two electric pumps
(preferably Carter 4070's) with one connected to each tank and NO selector
valve.
Because of the possibility of having to replace a pump with something
unknown on the road, I'd tie the two outputs in the line forward with two
check valves into a tee.
A pump power selector relay powered by the tank selector switch can be used
to power either pump from that switch.
Definitely bypass and remove the mechanical pump.
It's not an expensive upgrade yet gives redundancy, eliminates the
hard-to-change mechanical pump, eliminates the possibly troublesome old
ethanol-susceptible selector switch, and helps minimize vapor lock.
JWID,
Ken H.
On Sat, Apr 15, 2017 at 8:05 PM, Bob Dunahugh wrote:
> On Barb's 73 GMC. The pump is working fine. But if it quits on the road.
> Not simple for her to change. I can make an electric simple to change. I
> think it's a good idea for her. Any thoughts out there? Bob Dunahugh
>
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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] Good idea to remove a working mecanical fuel pump. [message #316093 is a reply to message #316077] |
Sun, 16 April 2017 00:17 |
BobDunahugh
Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA
Karma: 11
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Thanks for the input. Makes me feel better to recommend it. This working on her GMC is working out great. She's paying me $90 an hour to fix her GMC. And I'm paying her $90 an hour for help Linda. So we're both making good money. RIGHT? This is a fantastic situation for all of us. As we're getting some great things done for all. As to Barb's GMC. I'm finding it to be in good condition over all. PO did a good job of timely grease jobs, and oil changes. Plus many parts have been serviced. So now I'm looking to head off problems as best as I can for see. New starter, ignition switch, and some battery cables. Change engine oil, and FD gear lube. Fan, fan clutch, shroud, and new belts. Check front wheel bearings along with all steering components, and adjust steering gear box. Check rear pins for tightness, clean out grease, and lube. Raise up, and power wash undercarriage, and front suspension. Next replace trans, check gas lines, brake lines, install electric fuel pump, and get the generator running. Paint window frames satin black, then buff, and wax body. This GMC is her full time, and only home. North in the Summer, and the South in the Winter. So this GMC Glacier is everything for her. My hats off to her for living her dreams. Not everyone has the guts to do that. Bob Dunahugh
________________________________
On Barb's 73 GMC. The pump is working fine. But if it quits on the road. Not simple for her to change. I can make an electric simple to change. I think it's a good idea for her. Any thoughts out there? Bob Dunahugh
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| Re: [GMCnet] Good idea to remove a working mecanical fuel pump. [message #316095 is a reply to message #316077] |
Sun, 16 April 2017 03:36 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Reliability on most electric pumps is not as good as mechanical ones. I have several examples of that.
1. I have replaced one electric fuel pump on a GMC and no mechanical ones.
2. On low wing airplanes they will not fly with a bad pump. So we have 2 pumps in series just like most people do on an GMC. On aircraft I have replaced at least 10 electric fuel pumps and 0 mechanical ones.
3. In my life, I have replaced exactly one mechanical pump. That was on a 1954 Ford in about 1964. I have replaced 15 or 20 electrical pumps on various vehicles.
So by going to electric only, I suggest that you have increased your chances of an on the road failure. If I were to go to electric only pump solution on a GMC I would definitely go with TWO PUMPS plumbed in a way that the engine will run on either one by itself.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Good idea to remove a working mecanical fuel pump. [message #316096 is a reply to message #316077] |
Sun, 16 April 2017 04:49 |
davidlive
Messages: 143
Registered: November 2011
Location: Simi valley, Southern Cal...
Karma: -1
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I've only had a mechanical fail once in a 1973 Chevy suburban with a 454 , somehow it was leaking gas into the oil and the engine suffered a crankcase explosion, blowing out all the gaskets, at least once those were replaced the engine ran fine for years, but with that in mind I plan on putting my pumps in the tanks and if I keep the mechanical I'll put a surge tank in as well
David
78 Royal #749
74 #136
Oversteer is when you hit the wall with the rear of the car, understeer is when you hit the wall with the front of the car. Hp is how fast you hit the wall, and torque is how far you take the wall with you when you hit it.
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| Re: [GMCnet] Good idea to remove a working mecanical fuel pump. [message #316102 is a reply to message #316077] |
Sun, 16 April 2017 07:58 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Electric fuel pumps fail all the time. If they dont faill, the wiring/filters, relays do. I am surprised Bob, that you would suggest going away from a mechanical pump for her after your experience with your coach out to shawnee. Electrical pumps are good for efi, vapor lock, but i would not ever believe them to be more reliable. As far as gas in crankcase, a good new pump should not cause that worry. Electric pumps are also one of thise PO things that if you are. Ot the one to install them, having someone else work on them can be a pain to get it right the second time.
With that said, the gmc does need some sort of electic pump for vapor lock backup. But i put my reliability in a mechanical pump. I put on a new one on my coach because it was 40 years old, not because it did not work.
Like ken stated above, use two so you have a backup is the only way i would send someone else out on the road without the mechanical pump.
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: [GMCnet] Good idea to remove a working mecanical fuel pump. [message #316110 is a reply to message #316077] |
Sun, 16 April 2017 11:53 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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I would go with Ken Hendersons suggestion of the 2 P70 pumps and no mechanical pump. True mechanical pumps are more reliable but they tend to vapor lock real bad in many warm parts of the country with our cramp gas these days. With the 2 P70 pumps all you need to do is switch tanks with a failure and replace the bad pump when you get a chance with the spare that you carry. I have used the P70's in my GMC and hot rods for manny years with out a failure but you never know. As far as I know most vehicles use electric these days rather then mechanical ? Vapor lock will leave Barb on the side of the road in a bad location.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Good idea to remove a working mecanical fuel pump. [message #316112 is a reply to message #316110] |
Sun, 16 April 2017 12:08 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Need to know that until few years ago, mechanical pumps had the old
standard rubber diaphragm and not the newer ones that can tolerate ethanol.
Also the age of the pump.
Also your tank selector switch has the old rubber and need to be replaced.
Best to address it before it happens on the road.
On Sun, Apr 16, 2017 at 9:53 AM, roy keen wrote:
> I would go with Ken Hendersons suggestion of the 2 P70 pumps and no
> mechanical pump. True mechanical pumps are more reliable but they tend to
> vapor
> lock real bad in many warm parts of the country with our cramp gas these
> days. With the 2 P70 pumps all you need to do is switch tanks with a failure
> and replace the bad pump when you get a chance with the spare that you
> carry. I have used the P70's in my GMC and hot rods for manny years with
> out a
> failure but you never know. As far as I know most vehicles use electric
> these days rather then mechanical ? Vapor lock will leave Barb on the side
> of
> the road in a bad location.
> --
> Roy Keen
> Minden,NV
> 76 X Glenbrook
>
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Good idea to remove a working mecanical fuel pump. [message #316116 is a reply to message #316115] |
Sun, 16 April 2017 15:45 |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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Jp Benson wrote on Sun, 16 April 2017 15:12
I removed the mech. pump in the GMC and replaced with two Facet 40104s So far so good but they are a bit noisy.
JP
So is my P7040.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: [GMCnet] Good idea to remove a working mecanical fuel pump. [message #316137 is a reply to message #316096] |
Sun, 16 April 2017 22:56 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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On these old coaches your going to see more failed as they are old and the diaphragm cannot handle Ethanal.
Don't believe me, keep on running those old pumps
Get Outlook for iOS
________________________________
From: Gmclist on behalf of David Morrison
Sent: Sunday, April 16, 2017 2:49:05 AM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Good idea to remove a working mecanical fuel pump.
I've only had a mechanical fail once in a 1973 Chevy suburban with a 454 , somehow it was leaking gas into the oil and the engine suffered a crankcase
explosion, blowing out all the gaskets, at least once those were replaced the engine ran fine for years, but with that in mind I plan on putting my
pumps in the tanks and if I keep the mechanical I'll put a surge tank in as well
David
--
78 Royal #749
74 #136
Oversteer is when you hit the wall with the rear of the car, understeer is when you hit the wall with the front of the car. Hp is how fast you hit the
wall, and torque is how far you take the wall with you when you hit it.
_______________________________________________
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Unsubscribe or Change List Options:
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_______________________________________________
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Good idea to remove a working mecanical fuel pump. [message #316138 is a reply to message #316093] |
Sun, 16 April 2017 23:13 |
BobDunahugh
Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA
Karma: 11
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Senior Member |
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Alex I, and Ken H came to my rescue 2 miles from the Shawnee site. Alex found a Mr Gasket 5 to 7 PSI rotary pump. ( GM spec is 5.5 to 6.5 PSI.) Perfect. Got us home. I'm shying away from mechanicals. As I've had three of them leak lots of gas into the engine oil in the last 2 years. Then a new one fail last Sept coming back from Ohio. Then an electric fail going to Shawnee. So I'm gun shy. I'm putting EFI in our GMC soon with an external pump for each tank. That pump system seems safest to me. And Barb's likes the sound of that approach too. So now I need to get 2 external pumps to feed the carb for her. The pump that Alex got for me was a rotary. And I've never had problems with rotary pumps. I think the Carter 4070 is. Who makes the P30, and is it rotary? Barb live off the grid with her solar panels out in the desert with her dog during the Winter. Her GMC has to be the best it can. Bob Dunahugh
p70 4070
Thanks for the input. Makes me feel better to recommend it. This working on her GMC is working out great. She's paying me $90 an hour to fix her GMC. And I'm paying her $90 an hour for help Linda. So we're both making good money. RIGHT? This is a fantastic situation for all of us. As we're getting some great things done for all. As to Barb's GMC. I'm finding it to be in good condition over all. PO did a good job of timely grease jobs, and oil changes. Plus many parts have been serviced. So now I'm looking to head off problems as best as I can for see. New starter, ignition switch, and some battery cables. Change engine oil, and FD gear lube. Fan, fan clutch, shroud, and new belts. Check front wheel bearings along with all steering components, and adjust steering gear box. Check rear pins for tightness, clean out grease, and lube. Raise up, and power wash undercarriage, and front suspension. Next replace trans, check gas lines, brake lines, install electric fuel pump, and get the generator running. Paint window frames satin black, then buff, and wax body. This GMC is her full time, and only home. North in the Summer, and the South in the Winter. So this GMC Glacier is everything for her. My hats off to her for living her dreams. Not everyone has the guts to do that. Bob Dunahugh
________________________________
On Barb's 73 GMC. The pump is working fine. But if it quits on the road. Not simple for her to change. I can make an electric simple to change. I think it's a good idea for her. Any thoughts out there? Bob Dunahugh
_______________________________________________
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| Re: [GMCnet] Good idea to remove a working mecanical fuel pump. [message #316142 is a reply to message #316141] |
Mon, 17 April 2017 01:55 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Out of all of the stuff I use to carry, I only used 1 ignition module and 1 fan belt. I also did a precautionary change to my spare tire once.
A few years back I unloaded most of the spare stuff based on non-usage and weight. The heaviest stuff went first. I need to do the same with most of the tools that I carry.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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