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73-87 Chevy _ GMC Trucks => Interior & Equipment => Instrumentation => Topic started by: Tony_SS on December 02, 2008, 08:47:07 am

Title: Dual Gas Tank Operation?
Post by: Tony_SS on December 02, 2008, 08:47:07 am
Hi, so I'm new to these trucks (just got one yesterday) and I need to know the the dual tanks operate? I have a switch labeled L and R. Right now its on L. But I notice the gauge sometimes shows half a tank, then 3/4? it seems to be reading incorrect at times?? Can someone give me a basic rundown? Thanks
Title: Re: Dual Gas Tank Operation?
Post by: Tony_SS on December 02, 2008, 11:09:11 am
Opps I posted in the wrong section... can a mod move this?
Title: Re: Dual Gas Tank Operation?
Post by: Captkaos on December 02, 2008, 02:02:53 pm
Incorrect when driving, or incorrect at different times of the day?
Title: Re: Dual Gas Tank Operation?
Post by: Tony_SS on December 02, 2008, 03:38:25 pm
Incorrect when driving, or incorrect at different times of the day?

When driving...
Title: Re: Dual Gas Tank Operation?
Post by: DnStClr on December 02, 2008, 06:08:25 pm
There's a switching valve under the passenger door frame rail. When you operate the switch on the dash, the valve closes the electrical circuit to the first tank you were reading and opens the circuit to the other tank. If both right and left tanks are full, what does the gauge indicate when you switch tanks?
Title: Re: Dual Gas Tank Operation?
Post by: Tony_SS on December 09, 2008, 11:31:46 am
Never had both tanks full....

What happens when I flip the switch? Does the gauge just switch over and rear whats in that tank?
Title: Re: Dual Gas Tank Operation?
Post by: klineks on December 09, 2008, 11:47:47 am
I too have dual fuel tanks and my gauge does the same thing.  I think it is because there are not enough baffles inside the tank to keep the fuel from sloshing around.  That in turn causes the float attached to the sending unit to always be changing with the movement of the fuel.  I always check the gauge when I have been stopped for about a minute.
Title: Re: Dual Gas Tank Operation?
Post by: 79scottsdale on December 09, 2008, 12:09:00 pm
If you kneel down on the passenger side of the truck (at the rear of the door) and have someone flip the switch, you will hear an audible click from the valve when you switch tanks. Our guage is also all over the place when making turns, heavy acceleration, etc.
Title: Re: Dual Gas Tank Operation?
Post by: bigblue09 on December 11, 2008, 10:20:44 am
when im driving it will move around a lot. like from 1/2 to empty. but when im stopped it will stay in one place.
Title: Re: Dual Gas Tank Operation?
Post by: Bubba13 on December 24, 2008, 02:43:32 pm
Yup that was a poor design. I have the same dual tank setup also. My guages are all over the place also.
Title: Re: Dual Gas Tank Operation?
Post by: treepete on December 31, 2008, 10:09:14 pm
Does the fuel gauge in the dash also change which tank it monitors somehow?
Title: Re: Dual Gas Tank Operation?
Post by: DnStClr on January 01, 2009, 11:31:39 am
The gauge doesn't change anything guys. It only reacts to a change in the electrical signal that's sent to it. Or I should say- it changes according to resistance that the sending unit senses.
Title: Re: Dual Gas Tank Operation?
Post by: 79scottsdale on January 01, 2009, 05:26:16 pm
The gauge doesn't change anything guys. It only reacts to a change in the electrical signal that's sent to it. Or I should say- it changes according to resistance that the sending unit senses.

True, but I think treepete was asking if the guage can read each tank separately, and the answer is yes. Unless something is wrong, the guage will give you the tank fuel level of whatever tank you have selected with your switch, i.e. L or R.
Title: Re: Dual Gas Tank Operation?
Post by: Tony_SS on January 01, 2009, 09:40:11 pm
The gauge doesn't change anything guys. It only reacts to a change in the electrical signal that's sent to it. Or I should say- it changes according to resistance that the sending unit senses.

True, but I think treepete was asking if the guage can read each tank separately, and the answer is yes. Unless something is wrong, the guage will give you the tank fuel level of whatever tank you have selected with your switch, i.e. L or R.

Mine does not. It seems to only work on the left tank. Do you have to restart the truck with the switch flipped? or should the gauge change instantly with the switch?
Title: Re: Dual Gas Tank Operation?
Post by: bigblue09 on January 01, 2009, 09:56:31 pm
if your sitting at idle it should just switch.