gas gauge woes

so, pink and tan wire into the back of gauge. tan wire runs all the way back to the driver's rear, hits a clippy and shoots under the van to the top of the gas tank.. then a ground from the sending unit to, well.. a ground.

where is the power supposed to be in this whole equation? where can i test it? is there a way to zap my gauge to see if it'll even move without damaging it?

thanks donivan, i been on pins and needles all evening waiting for a response! i unclipped the plug under the tail light, and rigged up a makeshift ground with a section of wire and a blade terminal. hit the key, and the gauge pegged full! its a miracle! sooo... the tank has to come down but even at 38 degrees on a chilly montana night, that needle moving brought a smile to my face!

when the van is running, stopped, parked, {anything you can think of} the gauge reads a little under a half tank. its never moved the entire time i've owned her. i didn't try KEY ON, WIRE OFF.. but with KEY ON, WIRE GROUNDED the gauge slowly moved all the way to F. so it ought to drop all the way to E when the wire is loose?

i'm afraid of what i'll find in the tank!

My '69 once had a gas gauge that wouldn't work. It ended up being the brass float had a tiny hole that allowed it fill with gas and sink causing the gauge to always read EMPTY. I swapped the float and tested the sending unit with an ohm meter and all was well after that. Good luck in your search. I got tired of knocking on the tank before going anywhere.

i'm tearing the tank out in about 20 minutes. i'll be sure to have my camera handy. from the look of the hardware at the front of the straps, someone may have already been back here...

I backed the van up on jackstands under the carport to get the clearance i needed without having to roll around on the wet ground, the ground looks less than promising once i find and disconnect it, the straps were tweaked, but the tank came out anyway. the connections on top of the sending unit looked very clean, but the unit {floatless} and fuel from the tank were a rusty mess! I fished the float out with my fingertips to find it had been stuffed with corks! from mission mountain winery! i filtered the gas a few times and came up with what you see in the bottom of the bucket i had to put her back together without any new pieces because i'm broke right now! the gauge still doesn't read totally empty... still a little under half. so what sending unit do i get? or test this one? maybe the gauge in the dash isn't functioning? if i tear it down and put a new float in, will it read from that point up? SOOO MANY QUESTIONS!

i'll have to keep my eyes out for sure! the power and ground aren't a problem, but the unit is bad.

stealing guts doesn't seem too difficult. how do i find a vehicle with a 90 ohm resistor in its sending unit? are they labelled? pretty sure mine said 90 ohm under a fine coating of rust!

http://cgi.ebay.com/ebaymotors/AC-GAS-GAUGE-TANK-UNIT-CHEVROLET-GMC-TRUCK-1971-67-NOS_W0QQitemZ280365157986QQcmdZViewItemQQptZMotors_Car_Truck_Parts_Accessories?hash=item414710ce62

OUCH!!!!

https://vintage-vans.forumotion.com/g-van-general-discussion-f4/fuel-sending-unit-t5334.htm

I grabbed the sending unit out of my 77 gmc before I scrapped it and brazzed it to the top of the sending unit from my 67...The bottom line is 3/8 then the top line is the factory 5/16th... tested the gauge and it works fine but dont know if going from a 3/8 to a 5/16th line will make any difference???? Bent he float rod so it would read right when the tank was empty or full... I find out next spring when I get her fired up.