Gas mileage BLOWS!!!

[MYT HI]

my 94, which has a 90 engine/trans sucks the gas down. ill give some info on it.

-350 TBI engine
-700r4 built trans
-3.73 gears
-285/75 bfg all terrains
-true duals with headers
-4x4

so it uses about 1/4 tank to go about 10 miles. I feel that's insane!! it also smells terrible when running. I put a new O2 sensor in it and it didn't change. what do you think it could be? this is a keep or sell situation because of the mileage. any advice is appreciated


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[poncho62]

Needs a tune up?

How about some actual numbers? Fill it up, drive it for a few days, fill again....record gallons and mileage driven...That will give you a baseline to start with

 

[MYT HI]

forgot to add, it has new plugs and wires and cap


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[skylark]

About the only thing that I can see would be is a bad coolant temperature sensor (the one by the thermostat). Is it throwing any codes? I wouldn't drive it if it is truly that bad because it will wash all of the oil off of the rings rather quickly and tear up the cylinder walls.

 

[MYT HI]

there's no codes. what do you think that part would make it do?


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[someotherguy]

There's probably about eleventy-million threads about bad CTS causing an overly rich condition. Surprised you haven't seen it discussed before.

Also if your MAP sensor is disconnected you will run extremely rich. Sometimes the rubber boot on its vacuum line hardens up and doesn't seal well to its port at the rear of the TBI.

And what they said, fix it ASAP, and change your oil. It's totally diluted with gas. Running that rich is also murder on your cat, if you still have one.

Richard

 

[MYT HI]

what temp does your guys trucks run at? 180? mine typically runs at 210 and I'm not sure if that's hot or just right. I'm going to order the sensor and might do the thermostat too


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[SlowZ71]

Mine runs well below 210, maybe 185-190, and I get almost 18 mpg in a 91ECSB 350 tbi 4wd truck with 265/75r16 E loads. Granted, I drive like an old man (70 mph on the highway), but with stock steelies it's still heavy.


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[MYT HI]

thanks for all the help guys. I'll hit up the parts store tomorrow and hopefully get my mileage back


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[skylark]

what temp does your guys trucks run at? 180? mine typically runs at 210 and I'm not sure if that's hot or just right. I'm going to order the sensor and might do the thermostat too


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Where your trucks temperature runs at is only part of the equation. It is also what it thinks that it is running at. A bad CTS can read as low as -40. Richard has a good point about the map, I wasn't thinking completely apparently.