fuel gauge light

reservoirdog · Post by **reservoirdog** » Sat Oct 14, 2006 4:31 pm

I just finished taking apart and cleaning all my gauges. Thought the bulb was out on the fuel tank gauge prior to starting the project, but it seems to be an electrical issue as the bulb from that gauge works in the others. In fact all bulbs but the fuel gauge are light. Any suggestions? Can it be dirt in the bulb holder?

So Cal Mark · Post by **So Cal Mark** » Sat Oct 14, 2006 4:50 pm

check to see if there is power in that socket, if there is, ground the other side and see if the light works. If it does, check the sending unit in the fuel tank

mbouse · Post by **mbouse** » Sat Oct 14, 2006 7:47 pm

Are you talking the illumination light, or the red, get-mo-gas light?

sounds like you've eliminated the bulb as the problem.

i'd clean the socket well with a fine wire brush or steel wool - - making sure there was not any electrical power source in the vicinity first.

Radio Shack (and others) sell an inexpensive Volt-Ohm Meter that is real handy for these types of projects. They don't need to be accurate to demonstrate that power exists in a circuit. i'd recommend that every tool box have one.

reservoirdog · Post by **reservoirdog** » Sat Oct 14, 2006 8:34 pm

The illumination light - the get mo gas light works. But I may also have a problem with the fuel sender as the needle goes crazy once it gets below 1/2 tank. I already have a new one, but have been afraid to change it as I've never depressurized the fuel system. I'm not sure I have to do that for my 82 FI, given that the replacement sender does not seem to have a connect for the fuel line.

I'm going to try the voltmeter and will post back. Thanks for the input

So Cal Mark · Post by **So Cal Mark** » Sat Oct 14, 2006 10:00 pm

oh, I thought you meant the low fuel light didn't work. With the erratic gauge, you need to replace the sender. No need to relieve fuel pressure to change the sender.

mbouse · Post by **mbouse** » Sat Oct 14, 2006 10:48 pm

just take everything out of your trunk that you don't wanna spill gasoline on.

take out the sheet metal screws securing the ring to the tank. remove the hose clamps from the sender hoses. make sure you remember which wire goes where....

lift the old sender unit out.

properly install the gasket and install the new sender.

POC .. piece of cake.

the needle is only erratic below 1/2 tank, or all the time? if all the time, clean your electric connections at the sender first.

So Cal Mark · Post by **So Cal Mark** » Sat Oct 14, 2006 10:57 pm

no hoses on the sending unit in an FI car

reservoirdog · Post by **reservoirdog** » Sat Oct 14, 2006 11:09 pm

thanks, I'll change out the sender in the am, and off to Radio Shack for the Volt Ohm meter

So Cal Mark · Post by **So Cal Mark** » Sat Oct 14, 2006 11:47 pm

in place of a voltmeter you can use a simple test light also

reservoirdog · Post by **reservoirdog** » Sun Oct 15, 2006 12:08 pm

I found my Radioshack Digital multimeter last night, and I think I set it right by putting in on the test mode for dc current.

My working light showed between 8 and 9 volts, and the problem socket had wildly changing readings, generally with a m before the V. Can someone help me intrepret?

also, the speedo cable is unhooked from when I took the instrument panel off - looks like this just pushes on?

Noaki · Post by **Noaki** » Sun Oct 15, 2006 12:27 pm

mV stands for millivolt, that's 1/1000 of a volt. That's almost certainly your problem. As always with the electrical work make sure you check the ground aswell as the wires that run to the guage. Also check the connector, I have problems with those usually (usually my air flow meter, great having the car die when the wires jiggle too much).

The speedo cable does just push on, with a sleeve around the outside that pushes up to hold the little clamp arms in place so it doesn't slip off. Horrible description, but hopefully it'll help you figure it out.

reservoirdog · Post by **reservoirdog** » Sun Oct 15, 2006 12:49 pm

It was the ground! I pulled off a couple of the connectors and cleaned and it works. A miracle. Thank you all

Now some hand to hand combat with that speedo cable and I'm good to go ( I hope)

mbouse · Post by **mbouse** » Sun Oct 15, 2006 8:50 pm

woo hoo.

sorry about the misdirection on the hose....but, glad to know that yet another ground wire gremlin has bit the big one!!

reservoirdog · Post by **reservoirdog** » Sun Oct 15, 2006 10:45 pm

no problem on the hose - I changed the sender as well - also, I just emailed you on the brown wire and headlight relay upgrade. thanks to all