I'm driving a 1988 GM injector sedan. My MPG ratio had suddenly dropped after it was taken out of storage, having stayed in an outdoor garage for 2 years (California). MPG dropped close to 15%, which bites.
After I took it out, I only flushed oil, and burnt several tanks of gas. Air filter was changed before the storage, spark plugs/wires - 6K miles ago.
I have no computer codes.
Would appreciate ideas.
Was your gas treated before storage? You should have a professionnal clean your injectors, and the combustion chamber while you're at it. Have the plugs inspected, as well as all your sensors and thermostats.
Beside the obvious tune-up procedures, I'd also check for any rolling resistance. Tires and brakes. Tires sitting for 6yrs is bad for them and brake parts can rust. Jack the car and see how easily the wheels turn.
Dave S(Texas)
While we are guessing, a stuck t'stat can drop mpg suddenly after it sticks open. s
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