Weird electrical problems

[innoi]

I have to issues first my hazard lights flash bizare. It's not a steady flash pattern, very inconsistent and fast then slow. Second my fuel gauge has not worked since I bought my truck. But after I unplugged the wire that ran from
The gas tank to the fuse box it pegged full. But when it's utter in it pegs empty. Oh yeah and I forgot to mention that I had to pull the hazard fuse to get them to stop. Any suggestions on any of this.
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[dcasalena]

May I suggest letting the board know what year, model you have?
Some guys around here seem to have an expertise in particular eras and it would help to know what you are working on here.

Also what does this mean, "But when it's utter in it pegs empty."?

[innoi]

Sorry I have a 67 gmc pickup. That other part was a typo. When the wire from the gas tank is plugged into the fuse box the gas gauge peggs empty but when I unplug it it peggs full.
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[VetteVet]

You hazard flasher is bad try changing it with the turn signal flasher

The gas gauge will go to the past full position when you unplug the wire at the fuse panel or the same wire at the sender. It just means that it isn't getting a signal from the sending unit in the tank. Try unplugging it at the tank and see if it goes past full. If it does then the sender is grounded or more likely the float is full and will not rise when the tank is filled.
Be sure the key is on when you test it and don't try jumping any power wires to the tank sender as you might cause the gas in the tank to explode.

[innoi]

Tested the wire. It did just as you said when I unplugged it. So what does this mean I have a bad float? Or it's just stuck?
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[VetteVet]

Well it could be either one but in any case it has to come out and be checked. I would pull it out and move the float arm up and down to see if it was free. Then I'd check the float and see if it was full of gas. Finally I'd reconnect the sending wire and move the float arm and watch the fuel gauge for movement. Make sure that the sending unit flange is connected to a good ground.

[innoi]

I don't see a ground wire on my tank sender. Maybe that is the problem. Where shoud the ground wire be connected to? The same spot the that the wire goes to the fuse pannel?

[VetteVet]

When you check the float and sender to see if it moves the gauge, with the sending unit out of the tank, then you have to have the tan wire from the fuse panel connected to the terminal on the sender, and you have to have the flange connected to the vehicle ground to complete the path to ground for the gauge, and the resistor. in the sending unit. That's where the wire comes in. Normally the tank is connected to the vehicle frame and the sending unit flange is grounded through the tank. If you have an aftermarket tank that's non-metallic then you have to run a separate wire from the flange to the vehicle frame to ground the sending unit.

You can't connect a ground wire to the same place as the sending unit wire or the sending unit resistor will be bypassed and the fuel gauge will read empty all the time.
I hope this explains it better than my other post.