My gas mileage has suddenly dropped from getting about 15-20 to 9-12 mpg. Does anyone know why there would be such a sudden drop like that? fuel injectors? air filter? any help would be greatly appreciated!!

 

Just how are you figuring your gas mileage ??

Is this based over several tanks of fuel??

Be nice to know just what your driving here??

Has the performance dropped off any of the conditions you listed would really slow things down.

Has your driving style changed ??

locked your hubs in and forgot

Dropped tire pressure and forgot

Increased idle time

added a 1000 pounds payload

a good major tune up if you have not done one in a while

 

Sorry I guess I should have included all of that. Yes it is based over probably 6 tanks of fuel. Im driving a 4 cylinder 87 toyota pickup with 33 inch tires. The performance has remained the same. Driving style is the same.. Slow and steady. No I made sure to check my hubs. I guess I could look into tire pressure. All ive added is a tool box. I changed the plugs, wire, dist. cap and rotor, fuel filter. Guess I need to go ahead and complete the tuneup and see what happens. Thanks for the help!

 

Did the mpg drop before or after yhr tune-up? Did a lot of fuel leak when you changed the filter? I'm assuming its a carburetor, when did you last adjust that? When did you start running 33" tires? There are so many variables,man. You gotta give us more info

 

Did you close all the clips on the air filter housing after checking the filter?

 

Dirty air filter can really impact mileage and it's cheap / easy to fix. It's not necessarily likely, but I've seen a clogged cat make fuel economy drop off like that before. . .

 

If it is a carbureted engine, check to see if the air diverter door in the air breather is pulling hot air, off the exhaust manifold all the time. mine did this and it dropped my millage. To fix it I just plugged the vacuum line.

 

The mpg dropped before the tuneup down to about 8 mpg. I replaced the plugs and wires and it helped some. some fuel leaked but not alot. And my mpg dropped before I changed the fuel filter. Ive been running 33's for over two years.

 

Thanks for the info. I adjusted the carburetor today and cleaned the air filter. Auto parts store didnt have the right air filter im going to have to buy a new one online so I just blew it out with compressed air. Ill be filling it up tomorrow and checking what i get again. Ill keep ya'll posted. Thanks for the help everyone