Fuel gauge not working

[Trueoo7]

I have the Autometer gauges and they all were working fine until today. Ran out of gas, luckily at a friends house. He had a 5 gallon can of regular, so we poured it in and had to prime the pump but it started up. A little embarrasing to say the least. The gauge was reading in between 1/2 and 1/4 full. Went to fill it up and it only would take about 4.5 gallons more. (gauge still reads between 1/2 and 1/4 full) I thought these tanks held 14 total. I have the stainless steel type. When key is switched off the gauge comes all the way down to empty so its not stuck. Where do I go from here? Do I check the sending unit or the gauge. How hard is it to get to the sending unit, I guess I have to drop the tank. If its the gauge what do I test for?

Thanks
Trueoo7

[XXQQQME]

Well, you 've already determined that the float isn't stuck, it may have to be adjusted. Probly have to drain/drop tank to do this. Not a pretty picture, but remember that this Cobra stuff is a thing of "passion". My tank has a plate in the top that can be removed. The sending unit is attached to it. You may have the same set up, but nevertheless, you'll have to drop the tank.
Good Luck . . . NO SMOKING!!!

[davidlee]

You may want to go to Backdraft in the manufacturers forum. There was a number of posts concerning your problem. It had to do with the fuel vent line and the proper corrections. I don't know about the earlier BDRs but the current ones hold prox 19 gal fuel. I suspect your gauge is fine just not enough fuel in the tank. Go take out a loan and fil up. Ha.

David

[Blue Man]

Your problem may be the vent line. Check the line, you should be able to cut 8 to 10 inches off. Make sure is straight into the tank.

Good luck

Blue Man

[Trueoo7]

Was out with the car today and fuel gauge came all the way up to full, then throughout the day it worked normal slowly coming down to 3/4. Decided to fill up, just to be safe, and gauge stayed on 3/4 (took 6 gallons). When I got home I slapped the tank from underneath with my hand and gauge went to Empty, has not come back up yet. I don't think its the vent line anymore. Has anybody dropped a stainless steel tank on a BDR yet? Was wondering what to look for.
Thanks
Trueoo7

[HI Cobra]

Sounds like you might just have a loose wire that was
barely making contact and lost what little it had when
you slapped the tank.

Flip

[Doug I]

she's punishing you for smacking her

[TampaFla]

Shell & Texaco have been selling some high sulphur gas which corrodes the contacts in sending units (among other things). Supposedly it was limited to the South not New England, but once it gets in your gas tank you've got big problems/repairs.

[Excaliber]

I ran out of gas shortly after I got my ERA. I thought for sure the gauge must be broke, after all I had recently filled up and had hardly been anywhere!

17 gallon tank and 6 mpg. It runs out REAL quick!

Now up to 8 after some careful tuning.

[tfarhood]

I haven't run out of gas yet, but the gauge is acting differently now compared to the first few tank fulls. At first everything seemed normal, but the last three fill ups produce a reading short of full and it almost immediately drops to half tank in about 20 miles. I drove it about 80 miles the other day and it stayed near the half mark the whole time. I filled it up again just to check the tank and calculate milage. I got 13 mpg (about 60% hwy miles) and I know it holds 19 gallons. I know I can go about 200 miles per tank full. I'll just keep a milage log each time I fill up until I find a decent fix.

[Trueoo7]

I would be inclined to go with the high sulphur theory except I get gas at the same station with my other three cars and their gas gauges work fine. Looks like I'll be dropping the tank this coming winter, if my patience can last that long. Until then I'll have to keep a log of my mileage. Stay tuned !!!

Where's Boudy when you need him?


Trueoo7

[Boudy]

I'm not thinking that you have a gauge problem. It goes to zero when the key is turned off. That tells me that the gauge itself is not stuck and is responding properly to voltage levels issued to it.

Let me get the lowdown on the gauge itself and I can help you trouble shoot it better.

The overall steps, though, will be to feed the gauge with the various voltages to fully test its range.

Then, run the same test from the tank side. This will test the gauge with and without the wiring harness of the car.

At that point, if the connections at the tank are good, the sender is stuck and needs to be replaced. At which point I would tap on the tank with a rubber mallet to try and free it prior to dropping the tank.

Boudy

[Trueoo7]

Boudy
Thanks for the help, after slapping the tank with my hand the last time, it immediately went to empty and stayed there so it may be a loose connection at the tank. Haven't had the chance to take the car out recently to see if a few bumps will change things around, but when you get the info for testing everything, I'll be waiting.
Just curious if you've ever dropped a tank? Doesn't look too bad, a couple of angle iron braces need to be removed and disconnect the fuel line and fill line. Hardest part is draining the gas since I don't have access to a lift.

Thanks again
Trueoo7

[Boudy]

"hardest part"... Ha. Running it out of fuel was easy, remember. I've never dropped one, but there's only 4 bolts, some hoses, and it should lower with out removing anything else. Unless, yours is different from the ones in my shop. "Very Possible." I've still got an older car we use for demo and track days, I'll check it out in the next day or so.

Let me know if you run into any problems dropping it.

Boudy