1986 chevy gas tank switch

Having problems switch from right tank to left tank. And gas gauge is not reading correct filled both tanks.

The gas gauge on the 86 has a free floating reading for the gas (you will notice the gauge go up and down while you stop and go because the gas will slosh back and forth) For the gas gauge not working i would take off the gas tanks, open it up and look for the sensors in each one to see how they look. Then if they look ok check the connections for it. You can just follow the sensor cable up to where it connects to the computer or connection relay dealy :screwy: under and to the left a bit of the brake fluid resevoir (it's that way on my truck at least. 89 C1500)For it not being able to switch from tank to tank I would check the gas lines and make sure one or the other isnt clogged or leaking. I had braided heavy duty gas lines i put in myself a while ago and it got a pretty bad leak up next to manifold wich was no fun to fix. Theres nothing much else you can do that i can think of other than just taking the tanks off, checking the sensors, and then checking the gas lines to see why it wouldn't switch from tank to tank. If its none of those its probably something serious i cant even think of heh. Good luck with that and let me know how it goes, i had to do it to my truck, but i only had one tank. :naughty:

Actually, if his truck is an '86 Silverado, there's a fuse that is associated with that switch. Check your fuse panel (under dash - left side). I forget what the exact description on the panel is, but it was definitely there. I had this happen to me once, and it took me a few seconds to realize that the switch had to have a short, or that there was a fuse burned in the line.

-R.G. (Baton Rouge, LA)
1986 Chevy Silverado (SWB) - 262 ci., 4.3L V6

Also... I have had problems with the gauge going bad. What I noticed was that a full tank would read 1/4 tank on the gauge, half tank would read 1/8 tank on the gauge, and empty was just plain empty. Change the gauge out, and you're set (as far as correct gauge readings). I cannot remember what the gauge cost me, but I believe it was around $65 from the dealer (ordered part).

-Ron G. (Baton Rouge, LA)
1986 Chevy Silverado (SWB) - 262 ci., 4.3L V6

I have an '86, and I have the same problem. I have not yet had a chance to look at it, but I believe my problem may be a broken wire to the tank (I noticed a broken wire underneath the week before i noticed the problem). Here's how I would describe my problem, is this similar to yours?
The right tank is full. The left tank is 1/4 full. These are the actual ammounts. The guage reads the same (left hand tank fullness) regardless of where the switch is set. I could not hear the selector valve operate when I flipped the switch.

According to a wiring diagram I found:
There are 3 wires going to the tank (from the switch, there may be more from other sources). 2 wires (light and dark green) go from the switch to the valve. 1 wire (pink) goes from the tank level sender to the guage.
There is a pink wire from each tank to the selector valve. The left tank wire has a white strip on it, the right has a black stripe.

I have a similar problem with my 86' Silverado, it registers only whats in the passenger side gas tank, I have a full tank on the driver side, and I am unable to switch to this tank..regardless of what postion the switch is in, it only pulls fuel from the passenger side tank

I'm not sure about the 86 but on older models (mine's a 79) the electric switch/valve would default to the right tank when it quit working. In a pinch you can swap the lines on the valve and pull gas from the left tank to make it home on. I think the later models had a more complicated valve that also switched the return line or something to do with emissions.

Some of the later models had a motor driven valve that when you switched it, you needed to push and hold the switch for about 5-10 seconds to insure that it switched completely. If you just flipped the switch it might switch the guage but not the valve or it might partially switch the valve and stop between ports leaving you with no gas.

James

when my 77 did this, I found a wire knocked off att the fuse panel by the drivers left foot.
It is like an add on wire that pushes on next to a fuse.
Bob B

I Have A 79 Custom Deluxe Im Wanting To Put A Tank Selector Valve On It. Im Needing A Wiring Diagram To Complet The Job. Any Advice Would Be Great Help.