Gas Gauge Quit Working

bakerman6578 · 07-21-2009

ok ladies and gentlemen the other day I went to start my car and the gas gauge wouldn't work?

I checked the wire plug on the sending unit on the gas tank and that is fine i think. Me and my dad just drained the tank cleaned it and adjusted the sender float so it reads correctly. We put it all back together and it worked really good for awhile now all it reads is empty? We have the dash almost compleatly apart just things needed to drive the car work right now and yes i am almost positive we didnt unplug it or something like that. The only wiring we have taken out is for the old alarm and radio. Do you guys know how much extra wiring a late 90's alarm has??

The gauge did work after all this wiring we pulled out it just stopped working recently and that stuff has been out almost scince we bought the car. All help is greatly appreciated!!!

66 restomod · 07-21-2009

Do the oil pressure and water temp gauges work?

bmarty67 · 07-21-2009

If it worked for a while then just quit, I would recheck the entire sending unit or just drain the tank and replace the sending unit as a whole. They do not cost athat much.

Joes72/65 · 07-21-2009

You don't specify what year you car is, so I can only tell you what to check if it is a '65 or '66. With the ignition on and the sending unit disconnected, check for 5VDC at the sending unit plug. If it's there, your sending unit is probably bad. If it's not, leave it disconnected and check for 5VDC at both posts on the back of the fuel gauge. If you have 5 volts at both terminals, most likely the wire going back to the sending unit is broken somewhere. If you have 5 volts at one terminal only, most likely the gauge is bad (internal open circuit). If you have no power to either terminal post, most likely your instrument vaoltage regulator is bad, in which case your temperature gauge would not work either. Bear in mind these tests are not all-inclusive, but it's where I would start. Good luck!

pkviking · 07-21-2009

My experience with an intermittant gas gauge is that the brass float on the sending unit in the tank get a small crack and takes in some gas. Sometimes it'll float and work ok and sometimes it sinks to the bottom because it's too heavy. Replace the float or the complete sending unit. They are both pretty cheap.

bakerman6578 · 07-22-2009

ok im sorry it is a 66 with v8 sorry and bout the temp and oil pressure they do work but at the time they are "unplugged" the sending unit wire was routed on top of the intake and they got mealted together. that was another problem in it self...

66 restomod · 07-22-2009

Check with a meter for a pulsating voltage out of the voltage reg located next to the speedometer cable. Sounds you like you may have fried it.

If the gauge is reading empty, the regulator is probably not putting out any voltage (open circuit)

If it is bad, can make a solid state one for about 5 dollars or buy a replacement that may be bad also. Repop units do not have a good track record.

Here is a link for making a a solid state voltage regulator:
IVR

Good Luck and Be Safe
Ron