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| [GMCnet] Fuel Gauge reading? [message #236540] |
Sat, 18 January 2014 16:41  |
John Olson
Messages: 96
Registered: August 2013
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New owner question here.
For the below: Assume gauges/senders are functioning correctly. Driving on
level ground.
If fuel switch is set to MAIN, and fuel gauge reads as 1/2 full.
1. Does that mean the MAIN tank contains about 12 to 13 gallons (1/2 of 25
gal)? Or BOTH MAIN and AUX tanks have 12 to 13 gal remaining?
2. If Main tank reads as 'empty', Aux tank has about 7-9 gal remaining?
25 gal MAIN tank is rear, 25 gal AUX tank is front. Both are interconnected
via tube.
I've read the manuals and searched the forums first. Still confused here,
so any help is appreciated!
John Olson
76 Edgemont
Chicago, IL (currently nomadic around Phoenix - Lake Pleasant)
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76 Edgemonte
Fulltime traveler
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| Re: [GMCnet] Fuel Gauge reading? [message #236542 is a reply to message #236540] |
Sat, 18 January 2014 16:55  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| John Olson wrote on Sat, 18 January 2014 17:41 |
New owner question here.
For the below: Assume gauges/senders are functioning correctly. Driving on level ground.
If fuel switch is set to MAIN, and fuel gauge reads as 1/2 full.
1. Does that mean the MAIN tank contains about 12 to 13 gallons (1/2 of 25 gal)? Or BOTH MAIN and AUX tanks have 12 to 13 gal remaining?
2. If Main tank reads as 'empty', Aux tank has about 7-9 gal remaining?
25 gal MAIN tank is rear, 25 gal AUX tank is front. Both are interconnected
via tube.
I've read the manuals and searched the forums first. Still confused here,
so any help is appreciated!
John Olson
76 Edgemont
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John,
You are substantially correct, but I have found that if one runs the main tank to stumble there is more like 11~12 gallons in the Auxiliary tank. But, don't push your luck until you learn your coach and your gauges.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Fuel Gauge reading? [message #236544 is a reply to message #236540] |
Sat, 18 January 2014 17:14 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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depends if you run flat or up and down
read here
http://gmcmotorhome.info/tank.html
On Sat, Jan 18, 2014 at 2:41 PM, John Olson <johnolsondesign@gmail.com>wrote:
> New owner question here.
>
> For the below: Assume gauges/senders are functioning correctly. Driving on
> level ground.
>
>
> If fuel switch is set to MAIN, and fuel gauge reads as 1/2 full.
>
> 1. Does that mean the MAIN tank contains about 12 to 13 gallons (1/2 of 25
> gal)? Or BOTH MAIN and AUX tanks have 12 to 13 gal remaining?
>
> 2. If Main tank reads as 'empty', Aux tank has about 7-9 gal remaining?
>
>
> 25 gal MAIN tank is rear, 25 gal AUX tank is front. Both are interconnected
> via tube.
>
> I've read the manuals and searched the forums first. Still confused here,
> so any help is appreciated!
>
>
> John Olson
> 76 Edgemont
> Chicago, IL (currently nomadic around Phoenix - Lake Pleasant)
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] Fuel Gauge reading? [message #236547 is a reply to message #236540] |
Sat, 18 January 2014 17:31 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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John,
With the switch in MAIN you're reading the output of the MAIN tank sender. With the switch in AUX you're reading the AUX sender.
You can't accurately extrapolate how much is in the AUX tank when the switch is in MAIN and vice versa.
Just switch back and forth and you'll see what's in both tanks.
Regards,
Rob M.
-----Original Message-----
From: John Olson
New owner question here.
For the below: Assume gauges/senders are functioning correctly. Driving on level ground.
If fuel switch is set to MAIN, and fuel gauge reads as 1/2 full.
1. Does that mean the MAIN tank contains about 12 to 13 gallons (1/2 of 25 gal)? Or BOTH MAIN and AUX tanks have 12 to 13 gal
remaining?
2. If Main tank reads as 'empty', Aux tank has about 7-9 gal remaining?
25 gal MAIN tank is rear, 25 gal AUX tank is front. Both are interconnected via tube.
I've read the manuals and searched the forums first. Still confused here, so any help is appreciated!
John
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Fuel Gauge reading? [message #236562 is a reply to message #236548] |
Sat, 18 January 2014 21:02 |
John Olson
Messages: 96
Registered: August 2013
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Perfect! Thanks gents.
I see, a sender in each tank. I remember perusing photos of that but I
dimly didn't make that connection. All understood now.
Great idea to switch between tanks en-route to exercise the mechs.
I hear ya about not pushing it. Going south past Albuquerque, gauge read
near half, but hit a longish stretch of hwy without filling stations. Not
knowing exactly how much fuel remained was nerve wracking. Now I do thanks
to you folks.
As always, the help is appreciated!
John Olson
76 Edgemont (slowly morphing into boondock rig)
On Saturday, January 18, 2014, Dan Gregg <gregg_dan@hotmail.com> wrote:
>
>
> John, since you stated level ground, then what Matt said. You better know
> your coach and how the gauges work before really trying to let the tanks
> run low. I got caught out in rural North Dakota coasting into a fuel
> station. I flip my tank switch several times each day of travel to keep
> everything working. When mine says half tank on both I have used
> approximately 30 gallons and will fill the thing back up.
> Dan
>
> --
> Dan & Teri Gregg
> Dexter, Mo.
>
> http://danandteri.blogspot.com/
>
>
>
>
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John Olson
Cell | 773.315.9220
Skype | johnolsondesign
http://www.linkedin.com/in/johnolsondesign
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John Olson
76 Edgemonte
Fulltime traveler
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| Re: [GMCnet] Fuel Gauge reading? [message #236568 is a reply to message #236562] |
Sat, 18 January 2014 21:28 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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John,
A GMC will get 8-10 MPG (if you're lucky and keep your foot out of it!) That means you'll be able to go 400-500 miles between fill
ups (in theory).
Four hundred miles would be about 6.6 hours at 60 mph.
I drive about 200-300 miles then stop and refuel which gives me a break and fills the tanks with cool fuel reducing vapor lock
problems.
Regards,
Rob M.
-----Original Message-----
From: John Olson
Perfect! Thanks gents.
I see, a sender in each tank. I remember perusing photos of that but I
dimly didn't make that connection. All understood now.
Great idea to switch between tanks en-route to exercise the mechs.
I hear ya about not pushing it. Going south past Albuquerque, gauge read
near half, but hit a longish stretch of hwy without filling stations. Not
knowing exactly how much fuel remained was nerve wracking. Now I do thanks
to you folks.
As always, the help is appreciated!
John
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GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Fuel Gauge reading? [message #236578 is a reply to message #236540] |
Sat, 18 January 2014 21:54 |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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| John Olson wrote on Sat, 18 January 2014 16:41 |
...If fuel switch is set to MAIN, and fuel gauge reads as 1/2 full.
1. Does that mean the MAIN tank contains about 12 to 13 gallons (1/2 of 25 gal)? Or BOTH MAIN and AUX tanks have 12 to 13 gal remaining?
|
Because of the way they are plumbed together, they both have 1/2 a tank.| Quote: |
2. If Main tank reads as 'empty', Aux tank has about 7-9 gal remaining?
|
Most references say 6 gallons.| Quote: |
25 gal MAIN tank is rear, 25 gal AUX tank is front. Both are interconnected via tube.
|
Yes. And the interconnect tube (fill plumbing) is about a quarter of the way up from the bottom of the tanks. That's why both tanks are the same level until they drop to 1/4, after which the one that is selected continues to drop.
In hills, fuel moves from one tank to the other, aux to main and vice versa, depending on whether you are going up hill or down.
Pictures are here: http://gmcmotorhome.info/tank.html
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| Re: [GMCnet] Fuel Gauge reading? [message #236586 is a reply to message #236578] |
Sun, 19 January 2014 00:25 |
John Olson
Messages: 96
Registered: August 2013
Karma: 0
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Member |
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@ Gene and A -- Very cool. The illustration shows where the inputs and
outgoes are and what happens behind the scenes on hills, even with the Onan
uptake. No downward pointing steep hill parking if you want to fire up the
Onan. Good to know.
@ Robert -- good calculations and I'm glad you posted them. My natural math
skills resulted in Art School ;).
@ Dan -- Your initial help and tour of your rig at Branson has given a
jump start to our boondock mods. Now have 4 6v batts up front w linkpro
monitor. Spec-ing LP-fired flash water heater. I'm currently looking over
your pics of the greywater mods. Our beloved Edgemont has no grey tank
currently. Looking into that one. Well, this is a whole other topic for
another day...
Maybe this as a grey water solution? Portable is relative...
http://www.interstateproducts.com/images/75k_water_bladder_-_large.jpg
John Olson
76 Edgemont
Chicago, IL (Nomadic in AZ...wanting to rip apart a perfectly good GMC only
to reconfigure the water lines and ducts.)
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John Olson
76 Edgemonte
Fulltime traveler
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| Re: [GMCnet] Fuel Gauge reading? [message #236638 is a reply to message #236595] |
Sun, 19 January 2014 12:53 |
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Richard RV
Messages: 631
Registered: July 2012
Location: Full-timer for 12 years, ...
Karma: -17
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Senior Member |
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Hey John. I'm currently in Phoenix getting my coach roadworthy after having done a bunch of work. I'm planning on heading to Quartzsite for the big RV show either tomorrow or the next day.
I tried to send you a private message but it seems you're not set up to accept them. Send me a PM with your number and I'll call and we can introduce ourselves.
Richard
'77 Birchaven TZE...777;
'76 Palm Beach under construction;
‘76 Edgemont waiting its turn
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| Re: [GMCnet] Fuel Gauge reading? [message #236644 is a reply to message #236586] |
Sun, 19 January 2014 14:02 |
Adrien G.
Messages: 474
Registered: May 2008
Location: Burns Flat, OK 73624
Karma: 1
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John, ( Our beloved Edgemont has no grey tank currently. Looking into that one.)
Well, their is a way to put a grey water tank under the frame. And I would like to have thought of it when my frame was down, because it would be easier to do.
The idea is to put the grey tank (20 to 25 gal) where the main fuel tank is located now, vent and drain in through the floor, and tank drain on the left/right side depending how the black tank is situated and space available. It would requires relocating the #2(the one right behind the TB mount) xross frame members forward (to open that space for the Aux fuel tank) move the 2 fuel tank forward, modifying the fuel & vent lines and exhaust pipe after the Y area.
I think it's doable without dropping the frame. And I may yet do it myself.
FWIW just my thinkng.
Adrien & Jenny Genesoto
75 Glenbrook (26-3) Mods LS3.70 FD / Reaction Sys / 80mm Front&Intermidiate / Hydroboost / 16" Tires / Frame Rebuild / Interior Rebuild
Yuba City,Ca. Text 530-nine-3-three-3-nine-nine-6
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| Re: [GMCnet] Fuel Gauge reading? [message #236658 is a reply to message #236644] |
Sun, 19 January 2014 15:45 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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We have been experiencing on our customers coach along with mine, that the
selector switch is being eaten by the ethonal and end up pulling fuel from
both tank.
It is not common for the aux tank to show 1/2 and afte the main runs down,
thee is only 3-4 gallon left.
I will replace before next trip.
On Sun, Jan 19, 2014 at 12:02 PM, Adrien Genesoto <fixman54@syix.com> wrote:
>
>
> John, ( Our beloved Edgemont has no grey tank currently. Looking into
> that one.)
>
>
> Well, their is a way to put a grey water tank under the frame. And I would
> like to have thought of it when my frame was down, because it would be
> easier to do.
>
> The idea is to put the grey tank (20 to 25 gal) where the main fuel tank
> is located now, vent and drain in through the floor, and tank drain on the
> left/right side depending how the black tank is situated and space
> available. It would requires relocating the #2(the one right behind the TB
> mount) xross frame members forward (to open that space for the Aux fuel
> tank) move the 2 fuel tank forward, modifying the fuel & vent lines and
> exhaust pipe after the Y area.
>
> I think it's doable without dropping the frame. And I may yet do it myself.
>
> FWIW just my thinkng.
>
>
>
>
> --
> ”When we avoid the mistakes we might have made, we sometimes make
> the mistakes that we might have avoided.”
>
>
>
> Adrien & Jenny
> 75 Glenbrook
> Yuba City,Ca.
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> GMCnet mailing list
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> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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