Inconsistent mileage
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Joined: Mar 2004
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From: Kentucky
Inconsistent mileage
I filled my truck up this morning, and kept a close eye on my mileage in the last week, because I thought something was up. I got 277 miles out of the front tank, and refilled with 12.7 gallons, 21.8 mpg. I only got 177 miles out of the back tank, but had to refill with 13.4 gallons. That's only 13.2 mpg. I'm sure that both were completely full when I started measuring, and both were filled at the same station, same octane, same driving conditions and highways, same everything. What gives? 
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Freshman User
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From: Kentucky
I don't really think that's it. After filling, I ran my back tank first, and the gauge is moving just like it did before, but there's no place for the fuel to pump to, because the front tank is already full. My truck acts like it's running rough when I'm on this tank too, like it's flooding out. At idle, there is a big lope, and the engine shakes. I'll keep an eye on it, but any other suggestions?
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From: Kentucky
Okay, now I know that's not it. I got 180 miles on the back tank this time before it started missing. It still showed 1/8 of a tank when it started missing, and died completely. I switched to the front, started right up, and I've already driven 60 miles on the new tank, no engine shaking, no rough idle, nothing. Could it be the pump, or is there some sending sensor bad?
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Joined: Dec 2001
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From: Louisville,Ky.
It may show if it is actually seeing an overly lean or overly rich condition. You only have this problem on one tank?
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From: Kentucky
Yeah, only on the back tank. I just added a K&N filter, and I thought I'd been having trouble with oil on the MAF sensor, but this could be the problem instead. Like I said, no problems with the front, but when I switch to the back tank all hell breaks loose (mileage-wise). I guess I'll have the codes pulled and get that verdict and go from there. For now, I'm using only one tank, because I can't afford 13 mpg driving 130 miles a day!
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From: Kentucky
I guess sugar could cause the problems, right? Pump's working too hard, and there you go. Is there something I can run through the tank to try and clean it, or what? I'm out of ideas, short of just leaving it empty.
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Joined: Dec 2001
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From: Louisville,Ky.
I don't know, If you want to drop the tank, most radiator shops can dip it and clean it for you. You might want to drop it and inspect the inside to see if you can see anything. O don't know of anything that will clean it by just pouring it in.
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