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Discussion Starter #1
just got back from a 30 mile round trip, used 1/4 tank of gas doing so, being that works out to less than 6 mpg.

shes a 99 durango with a 5.2 and 150k on the clock.

recently checked all fluids, cap/rotor/sensor have just been replaced.

looking to get some ideas on what might be causing this horrible gas mileage.

current plan is to run some seafoam through it, then replace the spark plugs, and the o2 sensors. (only 2 correct?)

any other ideas on things that might be able to pick this up would be greatly appreciated.
 

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Discussion Starter #3
no i didnt refill it to test it, but last time the needle was at the 1/4 mark it took 40 bucks, and thats where its sitting again after about 60 to 90 miles
 

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Discussion Starter #6
thing purrs like a kitten, runs just fine, i have a hard time believing it could only be getting 6 mpg the way it runs. the exhaust smells just fine

it takes about 4-6 seconds to start when its cold, and right now its pissing coolant like nobody's business though.
 

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and right now its pissing coolant like nobody's business though.
From where?

If it was overly rich the engine would run cooler than normal and OBD2 always throws a code for bad O2 sensors.

I honestly don't think the 318 displaces enough to get 6mpg in regular driving. You have to beat that thing to get down that low and beat it bad. I'm a lead foot and still clear 12+MPG every tank in my 5.9.
 

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Last time I got close to that mpg, I was draging my parking brake. Does it coast ok and roll in gear at idle. Just a thought but it sounds like its fighting something.
 

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Mine has 160k on the clock and takes all of 1second to start cold. if warm it only takes a blip to start. Something doesn't seem right with yours in comparison. I did see slightly longer starts at one point, but a tuneup fixed that. go for the plugs. good quality inexpensive ones should be fine.

Where is the coolant coming from? a failing water pump could in theory put more load on the engine but I doubt it would cut your milage that badly.

Stuck in 4wd?
Rear diff letting go..any wirring/grinding from the rear end?

also check behind the vehicle and make sure there isn't a boat or other large object attached :funny:
 

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Discussion Starter #10
couldnt tell you where the coolant is coming from, alot was soaked by the time i noticed it. she rolls in neutral just fine, i dont think its draging the brakes.

as for the startup, just a little struggle when its cold, when its warm its just a blip and she goes.

4 by is off, and im not noticing any unusual grinding or wirring.

i was gonna bring it to the local stealership to check the coolant leak but they want 130 just for a checkup
 

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When my dak was leaking coolant I could smell it but never find the leak, turns out it was leaking behind the pump and onto the timing cover.
 

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Hell my 318 Ram only gets 8mpg, but then again it's got a 4bbl carb, 3 speed auto tranny w/ no overdrive, 3.23 gears, 4" lift, and 33" tall tires :jester:
 

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Still you should be gettin' better than 6, somethings wrong. I'd check everything else said before you take the lift and tires off, especially if you like the way it looks.
 

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Discussion Starter #17
no i dont like the way it looks a ton, i want to lower it, and the 32's tend to rub on the frame.

so i want to go back down to 31x10.5 or whatever it is, and lower it down where it should be
 

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How much heavier the durangos are anyway. That, the tall (and heavy) tires and lift could be your cause.

my dakota with stock sport lift (bout 1" away from max t-bar crank) and 31s is showing about 12 right now. if I baby it and drive alot of highway I see about 14.5 average.

My water pump went out about 10k mile ago, If I remember I just started to hear the wirring sound when the revs would go down coming to a stop... The first or second day I drove it negative F temps.
 

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Discussion Starter #19
unfortunatly im mostly a car guy, so i dont know how to tell if the truck has been lifter or not.

i wasnt expecting great gas mileage, was hoping for around 15 mpg if i was lucky, even 12 would be 100% better
 

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Yeah drop her back down and give her a tune up and check the o2 sensors.
 
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