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Old 02-19-2012, 05:41 PM   #1
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Excessive Fuel Consumption--any ideas?

Not the throttle body that I know of--no gas smell.

Fuel pump/regulator a year old--no probs.

Tires fine.

Valves/rings fine I think because no burning oil or excessive oil consumption.

Guessing I'm getting about 10mpg---when I bought it I was getting 24mpg.

I'm out of ideas--thanks.

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Old 02-19-2012, 05:48 PM   #2
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spark plug and wire?

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Old 02-19-2012, 05:52 PM   #3
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Sparks 6 months old but wires haven't been replaced since I bought it 3 years ago and they are kind of limp come to think about it.

Prompts stupid question: wires effect MPG to this degree?
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Old 02-19-2012, 06:39 PM   #4
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bad O2 sensor keeping it running too rich?

somebody stealing it?
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Old 02-19-2012, 07:10 PM   #5
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What are your plugs gapped at?
4.0 or 2.5?
Auto or MT?
size tires?
Gear ratio?
Hardtop or soft?

Might want to post some more info.
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Old 02-19-2012, 07:24 PM   #6
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Quote:
Originally Posted by Timberwolf View Post
bad O2 sensor keeping it running too rich?

somebody stealing it?
No evidence (that my limited brain can tell) that I'm running rich. And no theft, I park too close to the door!
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Old 02-19-2012, 07:25 PM   #7
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Originally Posted by brent in az View Post
Sparks 6 months old but wires haven't been replaced since I bought it 3 years ago and they are kind of limp come to think about it.

Prompts stupid question: wires effect MPG to this degree?


up to a point yes, if the electricity doesnt reach the spark plug, no fire so no power
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Old 02-19-2012, 07:25 PM   #8
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Originally Posted by 95YamJam View Post
What are your plugs gapped at?
4.0 or 2.5?
Auto or MT?
size tires?
Gear ratio?
Hardtop or soft?

Might want to post some more info.
Knew I forgot something. Got the bulletproof AMC 2.5, manual shift. Got 31X10.5 BFG's which isn't the issue (I think). Softop.
I got 24 mph with all these factors, now lately around 10.--brent
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Old 02-19-2012, 07:27 PM   #9
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Plugs gapped per underhood Jeep recomendations by yrs truly at .035.
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Old 02-19-2012, 07:56 PM   #10
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Wow yeah somethings wrong. I have the same motor and stuff but running 32's and get 20 city.

You haven't changed your driving habits i assume? Brake haning up any where? notice any smell after driving? Clogged cat or bum o2 would be a guess. Any codes?
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Old 02-19-2012, 08:01 PM   #11
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Originally Posted by 95YamJam View Post
Wow yeah somethings wrong. I have the same motor and stuff but running 32's and get 20 city.

You haven't changed your driving habits i assume? Brake haning up any where? notice any smell after driving? Clogged cat or bum o2 would be a guess. Any codes?
No unusual smells but brakes on last legs. No pulling. Habits same. Haven't run codes yet because they've been unreliable in the past.

Exhaust sounds normal-so could it still be cat?
Will check 02--
thanks for this advice.
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Old 02-19-2012, 08:04 PM   #12
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up to a point yes, if the electricity doesnt reach the spark plug, no fire so no power
Yeah, but I'm not losing power; have no power issues (besides owning a 4-banger!).

Do you mean if wires are furnishing minimum juice, then the engine/ignition sys is correcting itself and working harder?
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Old 02-19-2012, 08:25 PM   #13
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Christmas Tree Check

When it is very dark out, start the engine and open the hood. Check to see if there is any arcing along the spark plug wires. This will tell if they are arcing over but won't tell you if they have excessive resistance and won't fire the plug. But you should feel it missing then.

Thermostat at 195. Temp should be running 200. If not, it is running rich.

Check the timing. Could be something inside the distributer.

Did you replace the cap and rotor? Check the distributer cap to see if the carbon ball in the center is there.

Check to see that plugs are connected correctly.

Pull the plugs and see how they are burning.

Just some ideas.
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Old 02-19-2012, 08:32 PM   #14
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Originally Posted by ballistx View Post
When it is very dark out, start the engine and open the hood. Check to see if there is any arcing along the spark plug wires. This will tell if they are arcing over but won't tell you if they have excessive resistance and won't fire the plug. But you should feel it missing then.

Thermostat at 195. Temp should be running 200. If not, it is running rich.

Check the timing. Could be something inside the distributer.

Did you replace the cap and rotor? Check the distributer cap to see if the carbon ball in the center is there.

Check to see that plugs are connected correctly.

Pull the plugs and see how they are burning.

Just some ideas.
THANK YOU---Going to start some of this soon.
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Old 02-19-2012, 08:45 PM   #15
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some great info! i need to be doing this too. i feel like mine is drinking alot of fuel too
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Old 02-20-2012, 11:51 AM   #16
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I'm more amazed at you getting 24mpg
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Old 02-20-2012, 12:46 PM   #17
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I'm more amazed at you getting 24mpg





Me too
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Old 02-20-2012, 12:54 PM   #18
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Fellas--I accidentally transposed the numbers..I was getting 42mpg...

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Old 02-20-2012, 01:33 PM   #19
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A friend of mine run a 2000 TJ 2.5 5sp. small tires like 215s and get 24mpg all the time, he does drive slow. It wound not even help the way he drives if it had a 454-BBC, he still just Paw Paw's around. LOL
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Old 02-20-2012, 06:58 PM   #20
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If you get that rig back up to 24 mpg please let us know how to do it. Good luck!!! I'm only getting around 15mpg.
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Old 02-20-2012, 10:10 PM   #21
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A friend of mine run a 2000 TJ 2.5 5sp. small tires like 215s and get 24mpg all the time, he does drive slow. It wound not even help the way he drives if it had a 454-BBC, he still just Paw Paw's around. LOL
The 360 in my AMC J10 did better than I got in the AMC 2.5.
I'm young and I do drive slow (if you can afford a ticket/court/hassle in this day and age skip reading!) but 24 should not be hard to believe in a well-tuned, well-running 2.5. It was like this when I bought it. I have no mods. Will take ballistx's advice and concentrate on distributor and wires and ignition sys.

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