Poor MPG?
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Poor MPG?
My truck all of a sudden went to getting poor fuel mileage. Only have about a tank of fuel on oil change and changed fuel filter about 500 miles ago. I have noticed the truck here lately like once or twice kinda stumble while driving. Its like it cuts out at about 40 to 50 mph and then is fine. It does not throw a code or ses light or anything. I am wondering if the CPS could be going out and could this cause the drop in fuel mileage.
The truck also runs fine. No loss in power or anything.
The truck also runs fine. No loss in power or anything.
Logistics Pro
Joined: Jun 2005
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From: AZ
First I get a CPS from IH or Ebay and replace the CPS...though I do not think that is the problem. Then you would have a new CPS in the truck and a spare to carry with you (keep the socket and small breaker with the spare cps). Now to your problem...
I'm certainly no expert here, but I would start with checking for boost leaks...check all the boots on the pipes. You might want to make up or buy one of these to check for leaks:
http://www.dieselsite.com/index.asp?...ROD&ProdID=607
Then I think I'd look at the UVC harness to make sure it hasn't come loose or gotten chaffed. I'm sure someone more knowledgeable will be along shortly to give you good advice. Good luck with the problem...let us know how it goes.
I'm certainly no expert here, but I would start with checking for boost leaks...check all the boots on the pipes. You might want to make up or buy one of these to check for leaks:
http://www.dieselsite.com/index.asp?...ROD&ProdID=607
Then I think I'd look at the UVC harness to make sure it hasn't come loose or gotten chaffed. I'm sure someone more knowledgeable will be along shortly to give you good advice. Good luck with the problem...let us know how it goes.
Fleet Owner
Joined: Jun 2004
Posts: 25,090
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From: Rio Rico, AZ.
Originally Posted by tholt34
My truck all of a sudden went to getting poor fuel mileage. Only have about a tank of fuel on oil change and changed fuel filter about 500 miles ago. I have noticed the truck here lately like once or twice kinda stumble while driving. Its like it cuts out at about 40 to 50 mph and then is fine. It does not throw a code or ses light or anything. I am wondering if the CPS could be going out and could this cause the drop in fuel mileage.
The truck also runs fine. No loss in power or anything.
The truck also runs fine. No loss in power or anything.
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Kwikkordead,
It looks like it might be a little bit wet on that part of the motor. Its not dripping, just looks like maybe some seeping. Is it o-rings on the fuel drain bowl possibly leaking?
When i changed the fuel filter i did open up the drain to drain some fuel out so i didn't make a mess. That was the first i have opened the drain since i have had the truck, could i have air in the lines bad from that or just from opening that started a leak?
It looks like it might be a little bit wet on that part of the motor. Its not dripping, just looks like maybe some seeping. Is it o-rings on the fuel drain bowl possibly leaking?
When i changed the fuel filter i did open up the drain to drain some fuel out so i didn't make a mess. That was the first i have opened the drain since i have had the truck, could i have air in the lines bad from that or just from opening that started a leak?
Last edited by tholt34; Feb 2, 2007 at 09:40 AM.
Posting Guru
Joined: Sep 2006
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From: Montana
would the CPS cause poor mileage?? I thought if it was bad, you got no mileage due to trucky no worky.
could be a winter blend of fuel too. mine has dropped but its been below zero a few days . already replaced the O-rings due to leak.
good luck
could be a winter blend of fuel too. mine has dropped but its been below zero a few days . already replaced the O-rings due to leak.
good luck
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My mpg has dropped cause of ultra low sulfer diesel but it has been around 14 or 15 and is like 8 or 9 now. I am thinking it is the o-rings on the fuel drain bowl leaking or atleast i hope that is what it is.
I went ahead and ordered a blue cps and figured i would change and put the one thats in it in the glove box as a back up since i know the truck runs with it.
I went ahead and ordered a blue cps and figured i would change and put the one thats in it in the glove box as a back up since i know the truck runs with it.
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Logistics Pro
Joined: Jun 2005
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From: AZ
You may indeed have leaky o-rings but that will not account for that large a fuel mileage change UNLESS the fuel was pouring out onto the ground in an obvious puddle.
Let's say you got 15 mpg (as you said) and were averaging 60 miles per hour...in one hour you would burn 4 gallons of fuel (4 gals x 15 mpg = 60 miles) and at 9 mpg you would use 6.7 gallons of fuel (6.7 gals x 9 mpg = 60 miles). So the difference would be 2.7 gallons of diesel lost per hour (5+ ounces per minute
)...that is a lot of fuel and it would be all over the engine and engine bay.
I can't tell you what the problem is, but drain-valve o-rings alone won't account for that drastic a decrease in fuel mileage unless fuel was spraying out of the drain valve.
Let's say you got 15 mpg (as you said) and were averaging 60 miles per hour...in one hour you would burn 4 gallons of fuel (4 gals x 15 mpg = 60 miles) and at 9 mpg you would use 6.7 gallons of fuel (6.7 gals x 9 mpg = 60 miles). So the difference would be 2.7 gallons of diesel lost per hour (5+ ounces per minute
)...that is a lot of fuel and it would be all over the engine and engine bay. I can't tell you what the problem is, but drain-valve o-rings alone won't account for that drastic a decrease in fuel mileage unless fuel was spraying out of the drain valve.
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Thats kinda what i thought. It looks like it may be seeping some but not dripping or anything. I don't understand it really cause the truck runs fine. No rough idle or anything and power hasn't changed so i am kinda at a loss.
Elder User
Joined: Sep 2004
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From: N. Georgia
Maybe change the air filter. Mine will drop a MPG or so when it starts getting dirty. Next I might revisit the fuel filter just to make sure everything is OK since it started after the oil and fuel filter change.
Joe
Joe
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I just got my X about a week ago...so I'm learning from this site...so please excuse this rookie question...I tried to get the top off to get to the fuel filter by hand and it wouldn't budge...the guy at the international shop said to wedge a screw driver into it and to be careful not to crack it....I tried that and still it wouldn't budge...can anyone help ?
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Mikey,
When i do mine i use a pair of pliers. open them up and wedge it in the slots on top of the cap and twist it off.
My truck finally stumbled tonight driving home and the ses light came on. It through a p0344 code. It said camshaft position sensor circuit intermittent. I have a cps on the way but is there anyway the cps could cause bad fuel mileage? Thats the only thing i can contribute as to why my truck has decreased in fuel mileage.
When i do mine i use a pair of pliers. open them up and wedge it in the slots on top of the cap and twist it off.
My truck finally stumbled tonight driving home and the ses light came on. It through a p0344 code. It said camshaft position sensor circuit intermittent. I have a cps on the way but is there anyway the cps could cause bad fuel mileage? Thats the only thing i can contribute as to why my truck has decreased in fuel mileage.
Fleet Owner
Joined: Jun 2004
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From: Rio Rico, AZ.
Originally Posted by tholt34
Mikey,
When i do mine i use a pair of pliers. open them up and wedge it in the slots on top of the cap and twist it off.
My truck finally stumbled tonight driving home and the ses light came on. It through a p0344 code. It said camshaft position sensor circuit intermittent. I have a cps on the way but is there anyway the cps could cause bad fuel mileage? Thats the only thing i can contribute as to why my truck has decreased in fuel mileage.
When i do mine i use a pair of pliers. open them up and wedge it in the slots on top of the cap and twist it off.
My truck finally stumbled tonight driving home and the ses light came on. It through a p0344 code. It said camshaft position sensor circuit intermittent. I have a cps on the way but is there anyway the cps could cause bad fuel mileage? Thats the only thing i can contribute as to why my truck has decreased in fuel mileage.
The computer needs a nice clean signal from the CPS, not a ratty one.