6mpg!!!!!!!!!!!!!!!!!!!!

6mpg!!!!!!!!!!!!!!!!!!!!
T

trw

Jeeper
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Location
Houston, Texas
Vehicle(s)
1978 CJ-7, 1995 YJ
I thought my CJ was drinking too much gas.....even for a CJ, hell even for a stock 2bbl carb!!!

I'm not sure whether to be astounded, shocked, angry, happy, or sad (should I cry?) I knew CJs got bad gas mileage, but biblically?! This is close to the mileage of a giant RV bus!!!

so now I ask, what on earth could be causing such horrible mileage? The carb is freshly rebuilt by Champion (got it from Autozone) and it has new spark plugs. The engine does have a "miss" when you mash the gas it will hiccup and choke then it take off after it clears out.

could the timing cause this? does it need a new ignition? ahk 6mpg??@?@!!? :confused: is there a way I can get it up to 10 or 12? I find that more suitable.
 
trw said:
I thought my CJ was drinking too much gas.....even for a CJ, hell even for a stock 2bbl carb!!!

I'm not sure whether to be astounded, shocked, angry, happy, or sad (should I cry?) I knew CJs got bad gas mileage, but biblically?! This is close to the mileage of a giant RV bus!!!

so now I ask, what on earth could be causing such horrible mileage? The carb is freshly rebuilt by Champion (got it from Autozone) and it has new spark plugs. The engine does have a "miss" when you mash the gas it will hiccup and choke then it take off after it clears out.

could the timing cause this? does it need a new ignition? ahk 6mpg??@?@!!? :confused: is there a way I can get it up to 10 or 12? I find that more suitable.
Click to expand...

I'm running 400+ Horse Power 401V8 in 4500Lbs. Jeep & I get better mileage than that.:eek:
That's sucks for a "6". Your timing should not mess it up that bad, but it would contribute to it. It sounds rich. What do your plugs look like?
 
what is your gear ratio and wheel size??
 
Houston, you have a problem!!
I would think that if you were running that rich you would be able to smell it!!
I was always impressed with the difference in millage after a tune up. Have you done any ignition upgrades?? HEI, TFI, MSD??
 
trw said:
235/75R15 tires with 3.54 gears

I'll pull the plugs tomorrow when I can get to the garage.
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I would think 14 to 18 MPG with that setup. In good tune.
Did you just buy this rig, or do you have any history on it.
 
IOPort51 said:
Houston, you have a problem!!
I would think that if you were running that rich you would be able to smell it!!
I was always impressed with the difference in millage after a tune up. Have you done any ignition upgrades?? HEI, TFI, MSD??
Click to expand...

no upgrades what-so-ever, its a completely bone stock CJ :eek: and yes, I live in Houston, and I definitely have a problem :D

the entire fuel system is new though, from the tank to the carb, and I recently rebuilt the cooling system with a new radiator and hoses. I am running a 160* T-stat though, the Previous Owner put that in trying to battle overheating issues, so I wonder if that may contribute if the engine isn't warming up to its designed temperature (I've been meaning to swap back to the factory 195*).

I bought the CJ back in July, been working on little by little since, but as far as I know, it was neglected by the previous owner outright, it was used as a hunting Jeep on his ranch for the last few decades and it spent the last several years sitting, the guy I bought it from bought it from the original owner, put a new fuel system in it (minus the carb I put on) and then sold it to me and I've been slowly bringing it back to life, I guess its consolation that it runs very well minus the throttle hiccup and terrible mileage.
 
How's the exhaust? Could it be plugged up? Timing as in to much advance can contribute to running hot.
 
LongHorn said:
How's the exhaust? Could it be plugged up? Timing as in to much advance can contribute to running hot.
Click to expand...

you know, I didn't think about exhaust. It has the original exhaust from 1978, the original cat. converter and muffler, which is banged up a bit.

This CJ is also laiden with the smog setup, but it isn't working and its been bypassed with a shorter belt to run just the Powersteering.
 
ok, here are a few pics of one of my spark plugs, mind you these were new plugs put in back in July when I first got the Jeep

plug1.jpg
plug2.jpg
 
trw said:
ok, here are a few pics of one of my spark plugs, mind you these were new plugs put in back in July when I first got the Jeep

plug1.jpg
plug2.jpg
Click to expand...
the one on top looks good form the picture. I hope the one on bottom looks different in person or it way to lean.
 
trw said:
you know, I didn't think about exhaust. It has the original exhaust from 1978, the original cat. converter and muffler, which is banged up a bit.

This CJ is also laiden with the smog setup, but it isn't working and its been bypassed with a shorter belt to run just the Powersteering.
Click to expand...

the disconnected smog pump is not the problem. You can toss that in an appropriate receptacle. The original cat could be trouble.
 
trw said:
no upgrades what-so-ever, its a completely bone stock CJ :eek: and yes, I live in Houston, and I definitely have a problem :D

the entire fuel system is new though, from the tank to the carb, and I recently rebuilt the cooling system with a new radiator and hoses. I am running a 160* T-stat though, the Previous Owner put that in trying to battle overheating issues, so I wonder if that may contribute if the engine isn't warming up to its designed temperature (I've been meaning to swap back to the factory 195*).

I bought the CJ back in July, been working on little by little since, but as far as I know, it was neglected by the previous owner outright, it was used as a hunting Jeep on his ranch for the last few decades and it spent the last several years sitting, the guy I bought it from bought it from the original owner, put a new fuel system in it (minus the carb I put on) and then sold it to me and I've been slowly bringing it back to life, I guess its consolation that it runs very well minus the throttle hiccup and terrible mileage.
Click to expand...


I guess the Houston we have a problem line is a bit dated, It is a quote from the Apollo 13 mission. Oh well thats what being old is all about.

the plugs don't look rich, is there any chance there is a fuel leak? once again you would smell it.
I like the catalytic converter clogged idea that is where I would start, there are too many things you have mentioned that would clog the cat.
there is also the heat riser valve and you may even pull the EGR and see if it is clogged there.
 
IOPort51 said:
I guess the Houston we have a problem line is a bit dated, It is a quote from the Apollo 13 mission. Oh well thats what being old is all about.

the plugs don't look rich, is there any chance there is a fuel leak? once again you would smell it.
I like the catalytic converter clogged idea that is where I would start, there are too many things you have mentioned that would clog the cat.
there is also the heat riser valve and you may even pull the EGR and see if it is clogged there.
Click to expand...

I think IOPort51 may have some thing with the gas leak, maybe a leak in the fuel line, fuel filter, fuel pump. Something that only leaks when it's running.:confused:
 
Look around where there are clamps on the hardline. Thats a likely spot for rust to start on a line. 6 mpg?? Dang , Im trying to improve from 14 mpg.
LongHorn said:
I think IOPort51 may have some thing with the gas leak, maybe a leak in the fuel line, fuel filter, fuel pump. Something that only leaks when it's running.:confused:
Click to expand...
 
LongHorn said:
the one on top looks good form the picture. I hope the one on bottom looks different in person or it way to lean.
Click to expand...

What does the rest of the plugs look like? Hows the compression? vacume readings?
 
That's insane. You HAVE to have a leak someplace. I can't even imagine it running with it dumping that much fuel through the system.
 
I am going to suggest one more thing to try, this is reaching very hard but if it's not the gallons it’s the miles. Check the odometer?? go run between mile markers or have someone follow you and confirm the speed and mileage.
I am of course assuming that you are dividing the number of miles traveled by the number of gallons used.
:)
 
coldwater said:
That's insane. You HAVE to have a leak someplace. I can't even imagine it running with it dumping that much fuel through the system.
Click to expand...


LOL, Thats about what I get out on the trail :eek:

Rember mine is a v8 though.
 
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