reduced mpg
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reduced mpg
I found this site last night and hope someone can help me.
I purchased a 99 f250 v10 3.73 new in 1999.
I'm now pulling a smaller 5thw [9500 wet] and driving about 10mph slower.
I love the truck and haven't had any problems except fuel pump replaced 2 yrs. ago, because of dirty fuel. My problem is the mpg keeps going down. When new it averaged 8-9. towing, 14.5-16.5 empty on trips around 12 in my small town driving. The truck ran and pulled good except in the mountains. The mpg was good but not enough omp on the grades. At about 65000 miles the mpg started going down especially when towing. Its now a pretty steady 7.5 towing. At 75000 miles I changed the plugs, air and fuel filter had the tranny flushed and fluid changed. The mpg still stayed down so I installed 4.10 gears. That made a big improvement in towing and even increased the mpg .3
At last we get around to my guestion,
Is there something I'm missing that should be checked that could be defective.
Love the truck hate the MPG.
Thanks guys.
I purchased a 99 f250 v10 3.73 new in 1999.
I'm now pulling a smaller 5thw [9500 wet] and driving about 10mph slower.
I love the truck and haven't had any problems except fuel pump replaced 2 yrs. ago, because of dirty fuel. My problem is the mpg keeps going down. When new it averaged 8-9. towing, 14.5-16.5 empty on trips around 12 in my small town driving. The truck ran and pulled good except in the mountains. The mpg was good but not enough omp on the grades. At about 65000 miles the mpg started going down especially when towing. Its now a pretty steady 7.5 towing. At 75000 miles I changed the plugs, air and fuel filter had the tranny flushed and fluid changed. The mpg still stayed down so I installed 4.10 gears. That made a big improvement in towing and even increased the mpg .3
At last we get around to my guestion,
Is there something I'm missing that should be checked that could be defective.
Love the truck hate the MPG.
Thanks guys.
Posting Guru
Joined: Dec 2004
Posts: 1,713
Likes: 16
When new, you stated it averaged 8-9 towing and now it is getting 7.5 towing. that is only a 1.5 drop . With fuel prices the way they are that does cost more but so many things can cause a small drop in mileage. You have covered most of the obvious ones but that 1.5 could be do to fuel type, air pressure in your tires, keep them at max inflation for best mileage, even a wider tire can use a little more fuel. Good luck with the truck and if you find a fix, let us know, Wrenchtraveller.
Posting Guru
Joined: Mar 2002
Posts: 2,245
Likes: 16
From: Vancouver Wash USA
Originally Posted by ksrdrunner
I found this site last night and hope someone can help me.
I purchased a 99 f250 v10 3.73 new in 1999.
I'm now pulling a smaller 5thw [9500 wet] and driving about 10mph slower.
I love the truck and haven't had any problems except fuel pump replaced 2 yrs. ago, because of dirty fuel. My problem is the mpg keeps going down. When new it averaged 8-9. towing, 14.5-16.5 empty on trips around 12 in my small town driving. The truck ran and pulled good except in the mountains. The mpg was good but not enough omp on the grades. At about 65000 miles the mpg started going down especially when towing. Its now a pretty steady 7.5 towing. At 75000 miles I changed the plugs, air and fuel filter had the tranny flushed and fluid changed. The mpg still stayed down so I installed 4.10 gears. That made a big improvement in towing and even increased the mpg .3
At last we get around to my guestion,
Is there something I'm missing that should be checked that could be defective.
Love the truck hate the MPG.
Thanks guys.
I purchased a 99 f250 v10 3.73 new in 1999.
I'm now pulling a smaller 5thw [9500 wet] and driving about 10mph slower.
I love the truck and haven't had any problems except fuel pump replaced 2 yrs. ago, because of dirty fuel. My problem is the mpg keeps going down. When new it averaged 8-9. towing, 14.5-16.5 empty on trips around 12 in my small town driving. The truck ran and pulled good except in the mountains. The mpg was good but not enough omp on the grades. At about 65000 miles the mpg started going down especially when towing. Its now a pretty steady 7.5 towing. At 75000 miles I changed the plugs, air and fuel filter had the tranny flushed and fluid changed. The mpg still stayed down so I installed 4.10 gears. That made a big improvement in towing and even increased the mpg .3
At last we get around to my guestion,
Is there something I'm missing that should be checked that could be defective.
Love the truck hate the MPG.
Thanks guys.
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Thanks for the replys.
I'm cheap so I don't run the a/c and defroster unless I have to.
Tire's 65 front and 80 rear.
Oil 5-30 wt. Change oil about every 3-4000 miles. It don't use any oil. Would it help to go to a heaver oil? More compression maybe.
MPG is about the same in all the south western states.
Regular unleaded gas.
Kind of light footed on speed, 60-65 on interstates and 55-60 on back roads.
Where is the o2 sensor located and can it be bench checked? Approx price and is it easy to replace?
I'm cheap so I don't run the a/c and defroster unless I have to.
Tire's 65 front and 80 rear.
Oil 5-30 wt. Change oil about every 3-4000 miles. It don't use any oil. Would it help to go to a heaver oil? More compression maybe.
MPG is about the same in all the south western states.
Regular unleaded gas.
Kind of light footed on speed, 60-65 on interstates and 55-60 on back roads.
Where is the o2 sensor located and can it be bench checked? Approx price and is it easy to replace?
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Posting Guru
Joined: Mar 2002
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From: Vancouver Wash USA
Originally Posted by ksrdrunner
Thanks for the replys.
I'm cheap so I don't run the a/c and defroster unless I have to.
Tire's 65 front and 80 rear.
Oil 5-30 wt. Change oil about every 3-4000 miles. It don't use any oil. Would it help to go to a heaver oil? More compression maybe.
MPG is about the same in all the south western states.
Regular unleaded gas.
Kind of light footed on speed, 60-65 on interstates and 55-60 on back roads.
Where is the o2 sensor located and can it be bench checked? Approx price and is it easy to replace?
I'm cheap so I don't run the a/c and defroster unless I have to.
Tire's 65 front and 80 rear.
Oil 5-30 wt. Change oil about every 3-4000 miles. It don't use any oil. Would it help to go to a heaver oil? More compression maybe.
MPG is about the same in all the south western states.
Regular unleaded gas.
Kind of light footed on speed, 60-65 on interstates and 55-60 on back roads.
Where is the o2 sensor located and can it be bench checked? Approx price and is it easy to replace?
Fleet Mechanic
Joined: Apr 2001
Posts: 1,264
Likes: 0
Originally Posted by ksrdrunner
Where is the o2 sensor located and can it be bench checked? Approx price and is it easy to replace?
BTW, the Mass Air Flow sensor is located between the air filter housing and the thottle body.
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