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[GMCnet] More Fuel Seperator Info [message #107587] Sun, 05 December 2010 12:20 Go to next message
paul h cashman is currently offline  paul h cashman   United States
Messages: 176
Registered: May 2005
Karma: 0
Senior Member
Jack
I plugged my Vent Line at the Tanks ,several Years ago.
I did ,dill a small Hole in the old Cap ,I later replaced it with a Lockable
Gas Cap, that was vented.
I have had no problems ,no Gas Fumes in the Cab.
Paul Cashman
Riverdale GA
78 Transmode


I'm puzzled by all the comments about collapsing the tanks, fuel pump not
pumping because of vacuum, etc.. I just rechecked my gas cap which appears
to be original. It is designed to vent the tank to prevent a vacuum from
occurring. Is this a unique cap?? If not, the dire consequences outlined
above aren't valid.


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Paul H Cashman Riverdale Ga 1978 Transmode 1975 Corvette 1978 Beetle Convertible 1989 Harley Davidson Sportster
Re: [GMCnet] More Fuel Seperator Info [message #107596 is a reply to message #107587] Sun, 05 December 2010 14:55 Go to previous messageGo to next message
captjack is currently offline  captjack   United States
Messages: 271
Registered: February 2010
Location: Sebastopol, California
Karma: 1
Senior Member
Paul,
I'm pretty sure that your locking, vented, gas cap will only allow air to flow into the tank to prevent the tanks from being collapsed and will not allow fumes to flow out through it, to reduce pollution. This is exactly what my (thought to be OEM) gas cap does.

Plugging the vent lines, as you've done, would allow pressure to build up in the tanks, and not be released by the gas cap. This pressure would normally be relieved through the venting system to the canister. With the vent lines plugged, pressure would not be relieved and the pressure buildup would be higher on hot days when vapor lock is most prevalent. My theory has higher pressure increasing the temperature where vaporization occurs which would reduce the possibility of vapor lock. Have you ever had vapor lock problems such that you could detect they were less after you plugged the lines?

Thanks,


Jack Christensen - K6ROW, '76 Glenbrook/Clasco - "The Silver Bullet", Sebastopol, CA
Re: [GMCnet] More Fuel Seperator Info [message #107615 is a reply to message #107596] Sun, 05 December 2010 18:55 Go to previous messageGo to next message
John Sharpe is currently offline  John Sharpe   United States
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
Senior Member
Quote:

......I'm pretty sure that your locking, vented, gas cap will only allow air to flow into the tank to prevent the tanks from being collapsed and will not allow fumes to flow out through it, to reduce pollution. This is exactly what my (thought to be OEM) gas cap does......


This describes a non-vented fuel cap. A vented cap does allow fumes to escape to the atmosphere while venting the tank.


John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
Re: [GMCnet] More Fuel Seperator Info [message #107686 is a reply to message #107587] Mon, 06 December 2010 12:57 Go to previous messageGo to next message
Ray Erspamer is currently offline  Ray Erspamer   United States
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
Senior Member
The reason I brought the question up about plugging the vent lines and getting
rid of the separator completely was that my vacuum canister lines are not even
connected to the carb. I've done a lot of investigation on all of my engine vac
lines and I want to make sure everything is functioning right and if the
canisters are not even connected I'd rather remove them and get rid of all of
the extra stuff. I'm into simplification where ever possible.

In looking at Pauls post below, I may try plugging the lines and going to a
vented cap before I remove anything.

I read somewhere that someone just removed the separator and let the 2 tank
lines vent near the rear wheel well, considering that my open flame gas
refrigerator and water heater is right near there, I'd rather not do that.

Ray


Ray & Lisa Erspamer
78 Royale Center Kitchen
TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/




________________________________
From: Paul Cashman <paulcashman@bellsouth.net>
To: gmclist <gmclist@temp.gmcnet.org>
Sent: Sun, December 5, 2010 12:20:52 PM
Subject: [GMCnet] More Fuel Seperator Info

Jack
I plugged my Vent Line at the Tanks ,several Years ago.
I did ,dill a small Hole in the old Cap ,I later replaced it with a Lockable
Gas Cap, that was vented.
I have had no problems ,no Gas Fumes in the Cab.
Paul Cashman
Riverdale GA
78 Transmode


I'm puzzled by all the comments about collapsing the tanks, fuel pump not
pumping because of vacuum, etc.. I just rechecked my gas cap which appears
to be original. It is designed to vent the tank to prevent a vacuum from
occurring. Is this a unique cap?? If not, the dire consequences outlined
above aren't valid.


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Ray Erspamer 78 GMC Royale Center Kitchen 403, 3.70 Final Drive Holley Sniper Quadrajet EFI System, Holley Hyperspark Ignition System 414-484-9431
Re: [GMCnet] More Fuel Seperator Info [message #107689 is a reply to message #107686] Mon, 06 December 2010 14:16 Go to previous messageGo to next message
hal kading is currently offline  hal kading   United States
Messages: 642
Registered: February 2004
Location: Las Cruces NM
Karma: 4
Senior Member
Two considerations that may come up.

1. Coach may take fuel slower when refueling unless you tie the vents into the filler rather than plugging them.

2. Fuel may run out of the cap during hard or downhill stops or when fuel expands after refueling.

Hal Kading 77 Kingsley 455 Las Cruces NM
Re: [GMCnet] More Fuel Seperator Info [message #107728 is a reply to message #107686] Mon, 06 December 2010 20:15 Go to previous messageGo to next message
Dennis S is currently offline  Dennis S   United States
Messages: 3046
Registered: November 2005
Karma: 2
Senior Member

Ray and others considering removing the carbon canisters,

Please reconsider --

1) The fuel vapor venting and charcoal canister system if maintained as originally installed should not be a performance deterrent and may actually be good for the environment.

2) The more old/antique vintage cars that have the emission systems disabled or removed the more the proponents of removing old vehicles from the road can point to their potential negative impact and push for increased vehicle inspections and/or limited vehicle usage.

Just an opinion.


Dennis Sexton
73 GMC
Germantown, TN 38138-2066
USA



-----Original Message-----
From: Ray Erspamer <78gmc-royale@att.net>
To: gmclist@temp.gmcnet.org
Sent: Mon, Dec 6, 2010 12:57 pm
Subject: Re: [GMCnet] More Fuel Seperator Info


The reason I brought the question up about plugging the vent lines and getting
id of the separator completely was that my vacuum canister lines are not even
onnected to the carb. I've done a lot of investigation on all of my engine vac
lines and I want to make sure everything is functioning right and if the
anisters are not even connected I'd rather remove them and get rid of all of
he extra stuff. I'm into simplification where ever possible.
In looking at Pauls post below, I may try plugging the lines and going to a
ented cap before I remove anything.
I read somewhere that someone just removed the separator and let the 2 tank
ines vent near the rear wheel well, considering that my open flame gas
efrigerator and water heater is right near there, I'd rather not do that.
Ray

ay & Lisa Erspamer
8 Royale Center Kitchen
ZE368V101144
auwatosa, Wisconsin 53226
mail: 78GMC-Royale@att.net
14-745-3188
eb Site: http://ray-lisa.page.tl/

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Dennis S
73 Painted Desert 230
Memphis TN Metro
Re: [GMCnet] More Fuel Seperator Info [message #107729 is a reply to message #107587] Mon, 06 December 2010 20:23 Go to previous messageGo to next message
RadioActiveGMC is currently offline  RadioActiveGMC   United States
Messages: 1020
Registered: November 2010
Location: Hot AZ desert
Karma: 0
Senior Member
Looks like my charcoal filter was taken out of line a million years ago, Id have no clue how to hook it back up! Its currently in the landfill.

***"Gettin There"-1973 23' Sequoia- Michael, Onans smell, "Go solar/wind power!"
Re: [GMCnet] More Fuel Seperator Info [message #107749 is a reply to message #107729] Mon, 06 December 2010 22:03 Go to previous messageGo to next message
armandminnie is currently offline  armandminnie   United States
Messages: 864
Registered: May 2009
Location: Marana, AZ
Karma: 2
Senior Member
My charcoal canister is missing too. In trying to diagnose a strong fuel odor I was following the hoses around and broke the connector to mine - it was very brittle. Turns out that a PO had pulled the hose off of the carburetor and just left it hanging there in the engine compartment. The tank was venting through the fuel/vapor separator (it was also broken and allowing fuel to pass) and the canister into the area just in front of the co-pilot's seat. When it got hot during the day the fuel odor would get really strong.

I have considered all of the alternatives discussed on this forum and plan to replace the separator and the canister before next summer to try to fix the fuel odor that is now coming from the driver's side rear wheel well.


Armand Minnie
Marana, AZ
'76 Eleganza II TZE166V103202
visit my gmc blog
click here to visit gmcws.org
Re: [GMCnet] More Fuel Seperator Info [message #107753 is a reply to message #107587] Mon, 06 December 2010 22:33 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
Senior Member
The same cansister was used on thousands of 70s GM cars. They should still be a dime a dozen. It's a simple system. The intake filter disc on the bottom is replaceable and very inexpensive. No reason not to have this functioning as it should, no reason to give any more reason for anyone to say we are not emission compliant as per design. And the vapors get reclaimed and burned giving you better MPG to the tune of .0001 MPG increase. Better than breathing them.

John Lebetski
Woodstock, IL
77 Eleganza II
Re: [GMCnet] More Fuel Seperator Info [message #107778 is a reply to message #107753] Tue, 07 December 2010 08:39 Go to previous messageGo to next message
Ray Erspamer is currently offline  Ray Erspamer   United States
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
Senior Member
Okay, I'm really confused on something here. I just looked at all of the
manuals to try to understand the vacuum hose runs for the twin canister
system. Everything that has a diagram says "1978 California Vehicles Only".
I can't seem to find any good schematics for NON-CALIFORNIA vehicles. Am I
missing something? I'm wondering if my coach was a "California Emissions"
coach.

When I look at my vacuum hose runs they look nothing like the schematics I can
find, but I still have two canisters and neither are connected to anything.

I think I've searched and looked at vacuum hose diagrams off and on for 4 months
and I'm still confused as heck.......this can't be that hard....can it ?????

Ray


Ray & Lisa Erspamer
78 Royale Center Kitchen
TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/




________________________________
From: John R. Lebetski <gransport@aol.com>
To: gmclist@temp.gmcnet.org
Sent: Mon, December 6, 2010 10:33:15 PM
Subject: Re: [GMCnet] More Fuel Seperator Info



The same cansister was used on thousands of 70s GM cars. They should still be a
dime a dozen. It's a simple system. The intake filter disc on the bottom is
replaceable and very inexpensive. No reason not to have this functioning as it
should, no reason to give any more reason for anyone to say we are not emission
compliant as per design. And the vapors get reclaimed and burned giving you
better MPG to the tune of .0001 MPG increase. Better than breathing them.
--
John Lebetski
Chicago, IL
77 Eleganza II
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Ray Erspamer 78 GMC Royale Center Kitchen 403, 3.70 Final Drive Holley Sniper Quadrajet EFI System, Holley Hyperspark Ignition System 414-484-9431
Re: [GMCnet] More Fuel Seperator Info [message #107799 is a reply to message #107778] Tue, 07 December 2010 10:35 Go to previous messageGo to next message
mike miller   United States
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
Senior Member
Ray Erspamer wrote on Tue, 07 December 2010 06:39

Okay, I'm really confused on something here. I just looked at all of the
manuals to try to understand the vacuum hose runs for the twin canister
system. Everything that has a diagram says "1978 California Vehicles Only".
I can't seem to find any good schematics for NON-CALIFORNIA vehicles. Am I
missing something? I'm wondering if my coach was a "California Emissions"
coach. ...


California coaches came with two canisters. Federal coaches came with only one. While there where other small changes with the 455, most of the other "California differences" did not come in until the 403.


Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo' http://m000035.blogspot.com
Re: [GMCnet] More Fuel Seperator Info [message #107804 is a reply to message #107778] Tue, 07 December 2010 10:59 Go to previous messageGo to next message
C Boyd is currently offline  C Boyd   United States
Messages: 2629
Registered: April 2006
Karma: 18
Senior Member
[quote title=Ray Erspamer wrote on Tue, 07 December 2010 09:39]Okay, I'm really confused on something here. I just looked at all of the
manuals to try to understand the vacuum hose runs for the twin canister
system. Everything that has a diagram says "1978 California Vehicles Only".
I can't seem to find any good schematics for NON-CALIFORNIA vehicles. Am I
missing something? I'm wondering if my coach was a "California Emissions"
coach.

When I look at my vacuum hose runs they look nothing like the schematics I can
find, but I still have two canisters and neither are connected to anything.

I think I've searched and looked at vacuum hose diagrams off and on for 4 months
and I'm still confused as heck.......this can't be that hard....can it ?????

Ray


Ray & Lisa Erspamer
78 Royale Center Kitchen
TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/





Sir: 77-78 Supplement manual X7725, section 6T-6 has a good diagram for the twin canister model.
Thye 1974 emisions manual X-7482A has a good diagram for the early single canister.


C. Boyd
76 Crestmont
East Tennessee
Re: [GMCnet] More Fuel Seperator Info [message #107805 is a reply to message #107799] Tue, 07 December 2010 10:57 Go to previous messageGo to next message
Ray Erspamer is currently offline  Ray Erspamer   United States
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
Senior Member
Thanks. This tells me that I have a Calif emissions system, but it's been
modified and neither of the 2 canisters are connected...... man-o-man, what some
people do. I'll need to figure out what I want to do with the mess, I've got
all winter to think about it so no big rush.

Any recommendations ?

Ray


Ray & Lisa Erspamer
78 Royale Center Kitchen
TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/




________________________________
From: Mike Miller <m000035@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Tue, December 7, 2010 10:35:44 AM
Subject: Re: [GMCnet] More Fuel Seperator Info



Ray Erspamer wrote on Tue, 07 December 2010 06:39
> Okay, I'm really confused on something here. I just looked at all of the
> manuals to try to understand the vacuum hose runs for the twin canister
> system. Everything that has a diagram says "1978 California Vehicles Only".
>
>
> I can't seem to find any good schematics for NON-CALIFORNIA vehicles. Am I
> missing something? I'm wondering if my coach was a "California Emissions"
> coach. ...


California coaches came with two canisters. Federal coaches came with only one.
While there where other small changes with the 455, most of the other
"California differences" did not come in until the 403.

--
Mike Miller

#01 - `73 26' X Painted D. "The Spare"
#02 - `78 23' Birchaven Rear Bath "The User"
#03 - `77 23' Birchaven Side Bath "The Keeper"
Hillsboro, OR
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Ray Erspamer 78 GMC Royale Center Kitchen 403, 3.70 Final Drive Holley Sniper Quadrajet EFI System, Holley Hyperspark Ignition System 414-484-9431
Re: [GMCnet] More Fuel Seperator Info [message #107815 is a reply to message #107778] Tue, 07 December 2010 12:09 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
Messages: 6806
Registered: May 2010
Karma: -62
Senior Member
Ray, If you have two canisters, then you have a California Compliant Coach
evaporation emission system. In general, there is a very good explanation of
how it is supposed to be hooked up in the 77-78 Appendix manual that covers
changes only to the 77 & 78 Coaches, both the 49 states versions and the
California version as well. It is way more complex than descriptions on the
net will allow. If you have specific questions, ask me off net at
jamesh1296@gmail.com and I will walk you through it. Glad to help.
Jim Hupy
Salem, Or
78 Royale 403

On Tue, Dec 7, 2010 at 6:39 AM, Ray Erspamer <78gmc-royale@att.net> wrote:

> Okay, I'm really confused on something here. I just looked at all of the
> manuals to try to understand the vacuum hose runs for the twin canister
> system. Everything that has a diagram says "1978 California Vehicles
> Only".
> I can't seem to find any good schematics for NON-CALIFORNIA vehicles. Am
> I
> missing something? I'm wondering if my coach was a "California Emissions"
> coach.
>
> When I look at my vacuum hose runs they look nothing like the schematics I
> can
> find, but I still have two canisters and neither are connected to anything.
>
> I think I've searched and looked at vacuum hose diagrams off and on for 4
> months
> and I'm still confused as heck.......this can't be that hard....can it
> ?????
>
> Ray
>
>
> Ray & Lisa Erspamer
> 78 Royale Center Kitchen
> TZE368V101144
> Wauwatosa, Wisconsin 53226
> Email: 78GMC-Royale@att.net
> 414-745-3188
> Web Site: http://ray-lisa.page.tl/
>
>
>
>
> ________________________________
> From: John R. Lebetski <gransport@aol.com>
> To: gmclist@temp.gmcnet.org
> Sent: Mon, December 6, 2010 10:33:15 PM
> Subject: Re: [GMCnet] More Fuel Seperator Info
>
>
>
> The same cansister was used on thousands of 70s GM cars. They should
> still be a
> dime a dozen. It's a simple system. The intake filter disc on the bottom
> is
> replaceable and very inexpensive. No reason not to have this functioning as
> it
> should, no reason to give any more reason for anyone to say we are not
> emission
> compliant as per design. And the vapors get reclaimed and burned giving you
> better MPG to the tune of .0001 MPG increase. Better than breathing them.
> --
> John Lebetski
> Chicago, IL
> 77 Eleganza II
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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Re: [GMCnet] More Fuel Seperator Info [message #107824 is a reply to message #107804] Tue, 07 December 2010 13:46 Go to previous messageGo to next message
Ray Erspamer is currently offline  Ray Erspamer   United States
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
Senior Member
Charles, THANK YOU !!! The 1974 emissions manual X-7482A showing the diagram
for the single canister showed me exactly want I wanted to see. I'm going to
keep the one carbon canister and hook it up as shown and abandon the vapor one.
Nice clean system then.

I appreciate your help!

Ray


Ray & Lisa Erspamer
78 Royale Center Kitchen
TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/




________________________________
From: Charles Boyd <covered-wagon@comcast.net>
To: gmclist@temp.gmcnet.org
Sent: Tue, December 7, 2010 10:59:00 AM
Subject: Re: [GMCnet] More Fuel Seperator Info



[quote title=Ray Erspamer wrote on Tue, 07 December 2010 09:39]Okay, I'm really
confused on something here. I just looked at all of the

manuals to try to understand the vacuum hose runs for the twin canister
system. Everything that has a diagram says "1978 California Vehicles Only".

I can't seem to find any good schematics for NON-CALIFORNIA vehicles. Am I
missing something? I'm wondering if my coach was a "California Emissions"
coach.

When I look at my vacuum hose runs they look nothing like the schematics I can
find, but I still have two canisters and neither are connected to anything.

I think I've searched and looked at vacuum hose diagrams off and on for 4 months

and I'm still confused as heck.......this can't be that hard....can it ?????

Ray


Ray & Lisa Erspamer
78 Royale Center Kitchen
TZE368V101144
Wauwatosa, Wisconsin 53226
Email: mailto:78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/





Sir: 77-78 Supplement manual X7725, section 6T-6 has a good diagram for the
twin canister model.
Thye 1974 emisions manual X-7482A has a good diagram for the early single
canister.
--
C. Boyd
76 Crestmont by Midas
East Tennessee
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Ray Erspamer 78 GMC Royale Center Kitchen 403, 3.70 Final Drive Holley Sniper Quadrajet EFI System, Holley Hyperspark Ignition System 414-484-9431
Re: [GMCnet] More Fuel Seperator Info [message #107827 is a reply to message #107805] Tue, 07 December 2010 14:00 Go to previous messageGo to next message
rwbmitiopt@comcast.net is currently offline  rwbmitiopt@comcast.net   United States
Messages: 189
Registered: April 2005
Karma: 0
Senior Member
Ray
Sure, move to California where you can use your coach year round. LOL
Randall

Ray Erspamer wrote on Tue, 07 December 2010 08:57

Thanks. This tells me that I have a Calif emissions system, but it's been
modified and neither of the 2 canisters are connected...... man-o-man, what some
people do. I'll need to figure out what I want to do with the mess, I've got
all winter to think about it so no big rush.

Any recommendations ?

Ray


Ray & Lisa Erspamer
78 Royale Center Kitchen
TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/




________________________________
From: Mike Miller <m000035@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Tue, December 7, 2010 10:35:44 AM
Subject: Re: [GMCnet] More Fuel Seperator Info



Ray Erspamer wrote on Tue, 07 December 2010 06:39
> Okay, I'm really confused on something here. I just looked at all of the
> manuals to try to understand the vacuum hose runs for the twin canister
> system. Everything that has a diagram says "1978 California Vehicles Only".
>
>
> I can't seem to find any good schematics for NON-CALIFORNIA vehicles. Am I
> missing something? I'm wondering if my coach was a "California Emissions"
> coach. ...


California coaches came with two canisters. Federal coaches came with only one.
While there where other small changes with the 455, most of the other
"California differences" did not come in until the 403.

--
Mike Miller

#01 - `73 26' X Painted D. "The Spare"
#02 - `78 23' Birchaven Rear Bath "The User"
#03 - `77 23' Birchaven Side Bath "The Keeper"
Hillsboro, OR
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Randall Burns
Sammamish WA
75 EX GB
Re: [GMCnet] More Fuel Seperator Info [message #107843 is a reply to message #107824] Tue, 07 December 2010 16:40 Go to previous message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
While this topic is open, if anyone wants to see the inside of a
vapor/liquid separator:

http://www.gmcmhphotos.com/photos/showgallery.php?cat=5122

<http://www.gmcmhphotos.com/photos/showgallery.php?cat=5122>That shows my
separator which I keep repairing every few years; it had been repaired about
5 years before that album which was probably posted 3 years ago. Since I
had a couple of tank pressure incidents this summer, I suspect it needs
another treatment -- maybe, heaven forbid, even replacement.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
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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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