second tank problems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

pokethesmot · 01-22-2009, 01:21 PM

i was on my cigarette brake at school and i was sitting in my truck when i got bored and decided to flip the switch to see how much gas i got in my second tank and it went WAY past full...now the problem is...there should be anything more then a gallon or too of gas in that tank so whats messed up on my truck

TexasJeff · 01-22-2009, 01:44 PM

Mine does the same thing all the time, just turn the key on and off and it should reset itself and give you a true reading.

James McClure · 01-22-2009, 03:07 PM

This may reset the gage unless the sender is bad or the switching valve didn't switch all the way. Switch it back and forth several times to see what happens. Ask yourself if this has happened before. Switching valves are problematic at best in our trucks. I switch mine when 1 tank is at about half or a few times a week to keep it operational. If you don't use it, you'll loose it. jim

silvereagle07 · 01-22-2009, 05:57 PM

If you dont use the tank often, you may have sulfur build up on the fuel sender card. It will make it stick. If the truck will run off of that tank, put gas in the tank and add some chevron tecron fuel additive. It should clear up. Also like Jim said switch the tanks often to keep the valve working.

TexasJeff · 01-23-2009, 08:09 AM

I use both tanks all the time, and I put a brand new GM switching valve on it just 2 years ago, so it must have something to do with the sending unit, but I have had the problem with both tank to.

silvereagle07 · 01-23-2009, 08:50 AM

The sender card can get sulfur build up on it causing it to have and open circuit. My old truck did it all the time.

*78 Chevyrado* · 01-23-2009, 12:35 PM

When mine went way past full, it was the switch. They used some kind of foam to seal the switch (on the dash) and it had broken down and gotten between the contacts, making a bad connection on most of the contacts. I just took it apart and cleaned it out and Now it works perfectly. Take your switch apart if it's old, it's easy and free. Next step would be all connections, most likely outside the cab. The connections right on the top of the tank stay extremely filthy, but are hard to get to. Also check every ground you can find. Good luck

D-Monkey · 01-23-2009, 02:55 PM

guess I was lucky enough to have all that stuff gutted by the PO, i just have a petcock click it to the passenger side, it's that tank, drivers side is that tank, straight back is off... guess it's kind of a dummy switch since it's almost hidden under the seat

01-22-2009, 01:21 PM	#1
pokethesmot profeshinaly unimployed Join Date: Dec 2008 Location: hazlehurst, GA Posts: 1,232	second tank problems i was on my cigarette brake at school and i was sitting in my truck when i got bored and decided to flip the switch to see how much gas i got in my second tank and it went WAY past full...now the problem is...there should be anything more then a gallon or too of gas in that tank so whats messed up on my truck __________________ my ride click here my myspace "having mud flaps is like asking for a smaller trophy"

01-22-2009, 01:44 PM	#2
TexasJeff Don't Crush em Restore em Join Date: Aug 2004 Location: Pinehurst, Texas Posts: 764	Re: second tank problems Mine does the same thing all the time, just turn the key on and off and it should reset itself and give you a true reading. __________________ TexasJeff 2009 Silver with Linen Interior Cadillac DTS 1990 Red with White Top and Interior Ford Mustang GT convertible 1998 Red with Gray Interior, C3500 Chevy Crew Cab Dually

01-22-2009, 03:07 PM	#3
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: second tank problems This may reset the gage unless the sender is bad or the switching valve didn't switch all the way. Switch it back and forth several times to see what happens. Ask yourself if this has happened before. Switching valves are problematic at best in our trucks. I switch mine when 1 tank is at about half or a few times a week to keep it operational. If you don't use it, you'll loose it. jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

01-22-2009, 05:57 PM	#4
silvereagle07 Registered User Join Date: Sep 2008 Location: Bailey, NC Posts: 2,462	Re: second tank problems If you dont use the tank often, you may have sulfur build up on the fuel sender card. It will make it stick. If the truck will run off of that tank, put gas in the tank and add some chevron tecron fuel additive. It should clear up. Also like Jim said switch the tanks often to keep the valve working. __________________ Jeramy '84 GMC project truck '85 Chevy 4X4 SOLD '07 Chevy Trailblazer SS 5th Annual SHPHC Car/Truck Show Pics http://67-72chevytrucks.com/vboard/s...d.php?t=543605 UPDATED PICS! CHECK 'EM OUT

01-23-2009, 08:09 AM	#5
TexasJeff Don't Crush em Restore em Join Date: Aug 2004 Location: Pinehurst, Texas Posts: 764	Re: second tank problems I use both tanks all the time, and I put a brand new GM switching valve on it just 2 years ago, so it must have something to do with the sending unit, but I have had the problem with both tank to. __________________ TexasJeff 2009 Silver with Linen Interior Cadillac DTS 1990 Red with White Top and Interior Ford Mustang GT convertible 1998 Red with Gray Interior, C3500 Chevy Crew Cab Dually

01-23-2009, 08:50 AM	#6
silvereagle07 Registered User Join Date: Sep 2008 Location: Bailey, NC Posts: 2,462	Re: second tank problems The sender card can get sulfur build up on it causing it to have and open circuit. My old truck did it all the time. __________________ Jeramy '84 GMC project truck '85 Chevy 4X4 SOLD '07 Chevy Trailblazer SS 5th Annual SHPHC Car/Truck Show Pics http://67-72chevytrucks.com/vboard/s...d.php?t=543605 UPDATED PICS! CHECK 'EM OUT

01-23-2009, 12:35 PM	#7
78 Chevyrado Account Suspended Join Date: Dec 2007 Location: Unnapreciative, Trollville Posts: 2,079	Re: second tank problems When mine went way past full, it was the switch. They used some kind of foam to seal the switch (on the dash) and it had broken down and gotten between the contacts, making a bad connection on most of the contacts. I just took it apart and cleaned it out and Now it works perfectly. Take your switch apart if it's old, it's easy and free. Next step would be all connections, most likely outside the cab. The connections right on the top of the tank stay extremely filthy, but are hard to get to. Also check every ground you can find. Good luck

01-23-2009, 02:55 PM	#8
D-Monkey Registered User Join Date: Oct 2007 Location: SoCal Posts: 31	Re: second tank problems guess I was lucky enough to have all that stuff gutted by the PO, i just have a petcock click it to the passenger side, it's that tank, drivers side is that tank, straight back is off... guess it's kind of a dummy switch since it's almost hidden under the seat



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