| [GMCnet] fuel issue [message #88619] |
Tue, 15 June 2010 00:45  |
john arbuckle
Messages: 122
Registered: March 2010
Karma: 0
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Senior Member |
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Vapor lock?
Hey guys its john Arbuckle again. Well fuel continues to be an issue of
mine. I got the o grouch started but it continues to be an issue. I put a
new carer electric fuel pump dropped both tanks and replaced all the fuel
lines. This morning I went to start the thing and no go. I have to go to the
selector valve and disconnect the rear tank and place my finger over that
port, leaving the from tank connected. I turn on the ignition and gear the
fuel pump start up and then begin to prime. It then starts up. I then attach
the hose to the rear tank and it stays running for awhile. Once it runs for
awhile it begins to idle rough and dies. Is there something wrong with my
rear tank? Is the tank selector suppose to suck fuel through both ports when
running. Because I connected a piece of hose to one port of the selector and
turned on the pump and it drew gas out of a jar. With out touching the
switch in the cab I switched ports with the hose and it still drew gas out
of the jar. Any help would be great I am getting very frustrated with it.
Thanks guys.
John Arbuckle
1976 Palm beach
Tucson AZ.
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| Re: [GMCnet] fuel issue [message #88621 is a reply to message #88619] |
Tue, 15 June 2010 01:43  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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I'm not sure exactly what you are doing there but let me say this. If you disconnect a fuel line, usually all of the fuel will run back into the tank. Then when you try to start pumping again the pump (or pumps) have a difficult time pulling fuel back out of the tanks and through the lines.
What I have done in the past is to help the gas to initially get through the system and to the pump. I put a slight amount of pressure in the tank. This assists the movement of the fuel up through the lines and to the pump.
I do this by removing the gas filler and sticking a blow gun (attached to an air compressor) into the filler. I wrap the blow gun loosely with a rag and jam it in the filler. If you have an electric fuel pump you can turn it on. It does not take much air. I would say about 5 seconds worth.
Hit the air and start cranking the engine. I would not hold the air on for longer than 5 seconds at a time.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] fuel issue [message #88629 is a reply to message #88621] |
Tue, 15 June 2010 06:24 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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John,
If I understand your symptoms correctly, you've definitely got a bad
selector valve -- it should allow the fuel pump to draw from only one
tank at a time.
But, since you have to block the rear (main) tank port to get the pump
to draw from the front (aux) tank, there's apparently an air leak in
the plumbing to the rear tank. That's also consistent with losing
fuel flow when that line is reconnected, since the selector valve is
not isolating that circuit.
You may have to drop the tank again to fix the air leak.
It would probably cost little more for a second Carter 4070 fuel pump
and a few fittings than it will for the replacement selector valve --
dedicate a pump to each tank then you'll have complete redundancy and
will KNOW which tank is supplying fuel.
JWID,
Ken H.
Americus, GA
'76 X-Birchaven
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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| Re: [GMCnet] fuel issue [message #88641 is a reply to message #88629] |
Tue, 15 June 2010 08:16 |
mwall
Messages: 7
Registered: March 2004
Karma: 0
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Junior Member |
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Ken H.,
Sorry to hijack this thread but I've been trying to reach you via
private email but no response. I see you're posting so I'm wondering if
the love is gone...... Have I become spam?:)
Mark W.
76 E2
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Ken Henderson
Sent: Tuesday, June 15, 2010 6:24 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] fuel issue
John,
If I understand your symptoms correctly, you've definitely got a bad
selector valve -- it should allow the fuel pump to draw from only one
tank at a time.
But, since you have to block the rear (main) tank port to get the pump
to draw from the front (aux) tank, there's apparently an air leak in
the plumbing to the rear tank. That's also consistent with losing
fuel flow when that line is reconnected, since the selector valve is
not isolating that circuit.
You may have to drop the tank again to fix the air leak.
It would probably cost little more for a second Carter 4070 fuel pump
and a few fittings than it will for the replacement selector valve --
dedicate a pump to each tank then you'll have complete redundancy and
will KNOW which tank is supplying fuel.
JWID,
Ken H.
Americus, GA
'76 X-Birchaven
www.gmcwipersetc.com
_______________________________________________
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] fuel issue [message #88651 is a reply to message #88619] |
Tue, 15 June 2010 09:23 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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John,
I agree with Ken H. Symptoms point to a bad selector valve. Also, it sounds like you might have mixed up the connections to the pick-up on top of the tank. Could you have possibly hooked the fuel line up to the vent tube and vice-versa? If you have fuel in the rear tank. and your pump is drawing fuel through the valve from a jar, then that would explain it. The pump would be drawing air from the vent instead of fuel from the pick-up.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
[Updated on: Tue, 15 June 2010 09:23] Report message to a moderator |
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| Re: [GMCnet] fuel issue [message #88689 is a reply to message #88651] |
Tue, 15 June 2010 15:02 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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I replaced a failed valve for a friend of mine here a few years ago. It would suck through both ports and wasn't noticeable until one tank was empty and then of course it will suck air rather than fuel no matter which tank is empty.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] fuel issue [message #88701 is a reply to message #88619] |
Tue, 15 June 2010 15:52 |
Wander Inn
Messages: 100
Registered: January 2010
Location: Phoenix Az.
Karma: 0
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Senior Member |
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John;
Could the selcetor valve be plumbed wrong?
You could blow air thru it to find out if is
plumbed right and working.
Mike
Mike & Chris Hughes
1977 Kingsley
Phoenix, Az.
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| Re: [GMCnet] fuel issue [message #88710 is a reply to message #88701] |
Tue, 15 June 2010 16:35 |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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Senior Member |
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John, there are several folks trying to help you. Not only here but via email. Some live very close to you. Take a look in your personal email box, or give us an idea what you think after so many responses.
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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