When i connect a test light to the wire at the gas tank and turn the key on do the test light suppose to come on?
1979 ford thunderbird 8 cylinder the fuel gauge don't move when i turn the key to run and fuel is in the tank how do i test the sendit unit?
Cars & Trucks - Ford
Answers & Comments
First things first my friend. You must test the gage to be sure it is good. Normal procedure is: Switch off, unplug the wires from the sending unit at tank, connect jumper between the power wire and ground wire in the connector block, go to the switch and turn it to run position. If the needle goes to full, the gage is good. Turn the switch off. Now, be sure the connection is plugged in completely and you've a GOOD ground on the sending unit tab on the top of sending unit. No ground, no working needle. Use the test light to find if there's continuity with ground tab using power wire and touch the ground. No light, work with it till you do. Clean stuff to make the ground on tab work. Once test light does light between power and ground tab, your good. Gage should definitely be working now. If it doesn't work, this calls for replacing the sending unit in tank by dropping the tank first. Then it's easy to replace the sending unit.
Yes, from switch to gage, gage to sending unit, ground completes the circuit and gage will rise. Connect the two wires at the sending unit together, turn switch on, if gage rises it is a good gage. If no rise, a wire may be broken or ground is not well grounded to chassis.
Sorry it took so long to get back to you on this, I've been gone for 10 days from computer. Good luck with testing.