Bad fuel milage?

Question

Lately my 1990 Pontiac Sunbird has been absolutely HORRIBLE in gas. I drove 30 minutes today and went through a half a tank, but I used to be able to drive 4 hours on only half. WHY?

Answer 1

You have a severe fuel leak, or faulty fuel pressure regulator. The regulator can allow fuel to flow through the vacuum line  into the intake.

Answer 2

replace the pcv valve, fuel filter, and fix any leaks.

Answer 3

You are saying that you are using EIGHT times the gas now???

No I think you are mistaken.  Those old gauges are not very accurate and linear.  

Try measuring the gas usage instead of guessing. It might be that you indeed have bad gas mileage but not by 8 times.

Good Luck...

Answer 4

Verify your gas  mileage by filling up, driving, filing up again, calculate mileage.

If you are very far off of 25mpg with your car, it might be time to see a mechanic.  could be  an overdue tune-up, failed component, low tire, any number of things.

could also be someone stole your gas?

Answer 5

bad O2 sensor?

bad water temp sender?

leaking injector?

clogged catalytic converter or exhaust?

brakes dragging?