2001 Dodge Ram Bad fuel mileage and a code

2001 DODGE RAM
117,000 MILES • V8 • 2WD • AUTOMATIC
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OTMMA
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We just bought this truck and within 10 minutes of driving it I noticed that the fuel gauge was going down. The truck runs great and has plenty of power with no noticeable issues. I put 11 gallons in the truck and got 56 miles out of it and it was empty. Then the check engine light came on with a code of p1281 and also a vapor leak.

P1281 Which from my understanding says: The engine is staying cold for too long. So the thermostat and temp sensor was replaced. I went ahead and replace the oil sending unit and the air charge sensor as well. I replaced the fuel cap and that code went away.Still have the same code of p1281 and sucking the gas. What would be causing this problem and does the code p1281 cause the engine to use that much gas?
Dec 13, 2009 at 6:55 PM
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JACOBANDNICKOLAS
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Is the engine warming up in an acceptable amount of time? If so, you need to replace the ambient temp sensor. It tells the computer the outside temp and the engine temp. If it says that it's -40° F outside, the computer will compensate by making the fuel mixture very rich. Thus, you use a lot of gas.

Let me know if that helps.

Joe
Dec 14, 2009 at 10:51 AM
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OTMMA
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Thanks for the reply. I will replace that sensor today. I assume that the engine needs to reach, 170deg within 20 minutes, for the warm up time to be acceptable? If this is correct I need to verify that the replaced thermostat was a 170deg thermostat.
Dec 14, 2009 at 11:13 AM
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OTMMA
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I just verified that the thermostat was a 195deg unit. is this the right one?
Dec 14, 2009 at 11:17 AM
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OTMMA
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This truck does not have an interior console for the temperature thus it does not have the ambient air temperature sensor so that cant be the problem. I already replaced the air temp sensor that is in the intake.
Dec 14, 2009 at 6:34 PM
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JACOBANDNICKOLAS
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Yes, 195 is correct. Now why isn't the engine getting to that temp as a minimum? Was it doing this before you replaced it? I'm questioning if it is sticking open and not allowing the engine to heat up.

Let me know.

Joe
Dec 16, 2009 at 9:21 PM