88 Comanche Bad Gas Mileage

[OdinsMom]

My husband just bought an 88 Comanche as a daily driver and it is getting really bad gas mileage. He's pretty handy but doesn't know a whole lot about auto mechanics. What should be checked/changed to fix the problem?

Worth noting: the exhaust sticks out from under the front of the passenger's side of the bed. I assume that this was creative engineering and not how it should be.

[fredjacksonsan]

Welcome to AF.

"Creative Engineering"

The first thing I would ask about: how are the plugs, cap, plug wires and rotor? Putting new ones in should help. Also, sometimes an old air filter will cause issue with a sensor.

The exhaust, if some sort of backyard mechanic's special, could contribute to low mileage. Replacing it with a factory-type system might help.

If your vehicle has an O2 sensor (I think it does), then it could have failed causing the engine to run very rich. Is the inside of the exhaust black and wet after driving? If so, that's likely your problem.

Lastly, what mileage is he getting? What engine and how many miles on it?

[scoobytuff]

I would say to start with a good tune up. Plugs, distributor cap, rotor, spark plug wires, air filter and an oil change. Cleaning the throttle body won't hurt anything either. O2 sensors are usually pretty cheap and If it were me I would change that also. I'm not sure what kind of transmission the truck has, but while your doing a tune up would be a good time to service the transmission. It sounds like a lot of work and it really is. The more of this stuff you do in the beginning the easier it will be to keep track of in the future. All of this service stuff out of the way get him a fresh start and a good baseline on where the truck stands mechanically. I've even seen brakes that will slightly drag and have some horrendous effects on fuel economy. On the transmission part of it a slipping clutch in a manual transmission can cause bad gas mileage, and in an automatic transmission look at the kickdown cable adjustment. Really without going to far into it mechanically, get the thing a good tune up! You just can't go wrong there anyway you look at it.

[OdinsMom]

Thanks for your responses. I'll pass this info along to my husband and I guess we'll see how handy he really is I'm sure I'll have a bunch more questions so please check back later!! Thanks for your help!