Last September I bought my car. This is the first Trans am I ever owned.
I knew about the bad fuel consumption these cars have but in my case for sure there is a big problem...All this time I didn't had the chance to drive my car because I had to do some repairs. One week ago I started to use it for some weekend cruising and I realized that my fuel consumption is 5 MPG in the city!!!!!

My car has a cracked filler neck and I loose some fuel but only whenI fill it up.

I have replace: air filters, fuel filter, transmision filter and oil,oxygen sensor,TPS sensor, engine oil and filter, spark plugs, fuel pump...

My car is a 1982 Trans am with the 305 V8 crossfire engine and it has 92.000 original miles (engine is bone stock).

 

Make sure that map sensor is hooked to the right port, no vaccum leaks.
Check your coolant temp sensor, early ones were troublesome. Get a newer style sensor & pig tail.
Fuel evaporates, so that big leak is causing some of your fuel to go into the air. I've seen cars like that, the tank will become bone dry if you let it sit. Plus its very dangerous, get that fixed.

 

Thank for your reply!
Is it possible to have a map or a coolant sensor problem without a check engine code?
Someone told me to check also the injector/jets. What is your opinion?

 

This morning the car went to the mechanic to fix the filler neck problem.

 

i had the same problem but my car ran almost perfect so i knew it was someting other than the actual motor. it turned out to be that my o-ring to the fuel sending unit was worn and wasnt sealing properly changed that and i get to use every onnce of gas i put in the tank. haha

 

You mean the o-ring of the fuel pump?

 

Have you checked the ignition timing? Are any of the brakes sticking? How is the general driving experience? Are there any problems during acceleration or is it very sluggish? Does it need higher RPM than it should just to cruise around?

 

ignition timing o.k
brakes o.k
Driving experience good, acceleration good
RPM's normal

 

5mpg this is something abnormal, if your fuel does not leak anywhere and if car drive well check your engine oil for gasoline smell, it could be that gas is going down to oil. I know it can happen rare, but could be one of the reason. Also check you exhaust for gasoline presence.
Maybe you could first change you gas station, and fill up your tank fully to check properly your MPG.

 

Thank you for your help, It turn out that I had the same problem with you!

 

Glad I could help

 

What the...
How did you find THAT out?
It's not as if you could simply LOOK at that unit. did you remove the entire tank for that?

 

Have some shop smoke test it.

 

I have a little door that the previous owner made above the fuel sending unit. Thank god because I would of hated to drop the rearend and tank and that not be the problem. I knew the problem was something to do with the tank because I would fill up in the summer and by the next two days I would lose about 5 gallons of gas with the car just sitting there