Mechanics

RAPID DROP IN GAS MILEAGE

Buick Roadmaster

I own a 1995 Buick Roadmaster Wagon. It has approx. 137,000 miles. It has an LT-1 Corvette engine in it. It has always performed great on gas mileage. Usually 28 mpg on the highway and nothing under 23 mpg in town. I drove it on a 400 mile trip and got 28 mpg. Came home. My husband changed the air filter because we changed the oil and had not changed the air filter recently. I filled up and drove and gas mileage dropped to 10-15 mpg. I drove the tank out and filled up again, same thing. We checked tire pressure. Filled it up a 3rd time and still 15 mpg. It runs smooth. Starts fine. I have not changed gas. I go to the same gas station that has the best gas and all my cars run terrific on this gas. It is not ethanol. It is 93 octane. I have not checked the fuel pump yet, but could it just have an immediate effect like that. The only think different was the air
filter. Any ideas?
Avatar
Cathy14
November 5, 2006.



I might have found part of the problem with my gas mileage. We replaced the brake pads and than the car started smelling hot by the wheels. We checked the rotor and it needed to be replaced. Put a different set of new brake shoes just to be safe. It smelled hot again. We have now determined the calipers are stuck and we are going to replace those. In this process we also discovered my front tire was very bad and we replaced the tires. I am assuming that with the calipers sticking the brakes are dragging and this would be causing some of the gas mileage problem. I will have to see after we get things finished.

Tiny
Cathy14
Nov 11, 2006.
Is it heating up prperly?
The thermostat could be faulty, not closing fully, and letting coolant constantly flow through.
That would make it run very rich all the time, like it was warming up, and you'd get horrible mileage.

Tiny
NewtownPA
Nov 21, 2006.