Just got a "new" 1978 T-bird.

[JoeD]

It's not quite as low mileage as the '79 I was considering last year, but it's still pretty good at a documented 10,400 miles (well, now that I've driven it some, it's just turned over 11,000 miles). The car is a 1978 Town Landau, 400 V8 and C6 transmission. It's clearly been well cared for its whole life, and you could practically eat off the underside. The only rust I could find was minor surface rust where water drips off the air conditioner. A little Eastwood rust encapsulator and chassis black took care of it.

About the only problem I've run into is the fuel gauge. I'm wondering if it's stuck or if it's supposed to do this: It takes forever to start going down from FULL. In the last gas stop I made, it was showing squarely on 3/4 full, yet I could put 14.5 gallons into a 22 gallon tank. That can't be right. On the plus side, it got a solid 15.1 mpg, so now that I know the fuel economy, I'll drive it a little farther (carefully, of course, so I don't run out of gas) and see if it ever drops to empty.

Are the fuel gauges supposed to work this way? A co-worker did tell me the Chevy Blazer she used to have would take forever to go from FULL to half tank, then sank like a stone from there to empty. I have read where sometimes automakers would design the fuel gauge to do this, so it's possible that it's supposed to do this.




Thanks,
Joe

[Tim Cole]

Joe:

Welcome to the T-Bird forum.
Per your question, I own a 1978 Thunderbird Diamond Jubilee with a 351M (400 Block with 351C Heads) and a 1979 T-Bird with a 302-2v.

My gas gauge in the 79 Bird with the 302 operates normally like other vehicles.

But my Diamond Jubilee (351M) does the same thing as yours: Slow descent of the needle from full to half, and then quick descent from half to empty. I ran out of gas when I first drove the car. So, now, I never let it get past 1/4 tank, especially on the open road.

Don't know why they are different.

Tim
Florida

[JoeD]

Thanks. It looks like maybe a design flaw with the 1978 models, then. I was afraid the gauge was bad the first tankful since it seemed it never left full. It was only as I got a feel for fuel consumption rate and got bold enough to keep going that I finally confirmed the gauge actually moved.



Joe

[Tim Cole]

Originally Posted by JoeD

Thanks. It looks like maybe a design flaw with the 1978 models, then. I was afraid the gauge was bad the first tankful since it seemed it never left full. It was only as I got a feel for fuel consumption rate and got bold enough to keep going that I finally confirmed the gauge actually moved.



Joe

Joe:

I have a ton of parts for a 1978 Bird if you need anything. Just let me know. Tim; [email protected]

[55vicky]

I think it has more to do with the shape of the fuel tank than any problem with the gauge. They are fatter at the top and hold more gas so it takes longer to make it start to drop. I had a new '77 Monte Carlo once and the gas gauge wouldn't move at all off of full until I drove a 100 miles or so. My Tbird does the same.
DJ '79 Heritage

[g_lower]

both of my 79 cougars are like that, so its not just a 78 design flaw. :D plus if you fill it all the way up the neck its gonna take longer for the guage to come down off of the full mark.