Chief Comanche Posted October 2, 2012 Share Posted October 2, 2012 I have a 92 MJ 4.0 all stockstock that has recently had the fuel pump and sending unit replaced. Before this occurred the original owner never noted the has mileage to a tank of gas. There are no apparent problems with the truck like MAP sensor, o2 sensor, vacuum leaks our anything as it all has been replaced and or fixed. Since having the new fuel pump and sending unit replaced, after a fill up the gas light is on and the tank its showing empty after 190 miles. So with all that said, how many miles should I expect to get out of tank of gas? Link to comment Share on other sites More sharing options...
Exgrayxj Posted October 2, 2012 Share Posted October 2, 2012 On my '90, last fill up netted me 13.46 mpg. Some trips back and forth to work,(6 mi ea way) a little other driving and a lot of idling, to see if the overheating problem was any better. And, YAY! it is. Hoping for better next tank. 4.0 AW4 4wd 265/75/16 tires, corrected speedo. Link to comment Share on other sites More sharing options...
cruiser54 Posted October 2, 2012 Share Posted October 2, 2012 Bad sending unit or wrong one for your tank? Calculate your MPGs by dividing the number of miles driven by the number of gallons used from full. Link to comment Share on other sites More sharing options...
johnj92131 Posted October 2, 2012 Share Posted October 2, 2012 Miles per tank? Without knowiing the size of the tank? Long bed has 23.5 gallon tank, short bet has 18 gallon tank. And you don't know at what tank level the "gas light" comes on. First thing I would do fill the truck with gas, write down what the odometer reading was, i.e. 190612 miles. Second, drive your truck like normal and make some notes as to what "normal" is for you. Third, when the "gas light" goes on, write down the odometer reading is. i.e. 190802 Fourth, fill the truck with gas. Note how much gas you put in the truck and again write down your odometer reading, i.e. 190818 miles and 15.100 gallons Now, do the math. In my example, you drove 206 miles on 15.1 gallons of gas for 13.64 mpg. Using that mpg figure, when the light went on you had burned 14 gallons of gas and if you have a normal 18 gal short bed tank, you still had 4 gallons of gas in your tank. Here is a thread listing how many miles per tank: http://comancheclub.com/topic/29859-whats-the-most-miles-you-got-from-a-full-tank/?do=findComment&comment=304222 Link to comment Share on other sites More sharing options...
Chief Comanche Posted October 2, 2012 Author Share Posted October 2, 2012 First, thanks to each of you that had responded. I do understand how to calculate the examples provided but what I was needing to determine the total miles I should be getting to a tank of gas under normal driving conditions? Or did they put the wrong type of sending unit in the truck? To explain in more detail, on my last fill up I put 9.3 gallons in the tank and it was full fuel coming out. I then drive a total of 168 miles then the fuel light came on and stayed and fuel level indicated empty inside the truck. The tank is a 18.5 gallon tank in my short bed mj. Therefore without driving until emptying the tank and having to carry a gas can everywhere I go, I would like to know is an estimate of total miles to a tank I can expect? I realize they aren't the best in fuel economy but 168 total miles / 18.5 tank size and full= 9.08 miles per gal isn't good. Hope this explained better Link to comment Share on other sites More sharing options...
Eagle Posted October 2, 2012 Share Posted October 2, 2012 So with all that said, how many miles should I expect to get out of tank of gas? What size tank? The way to calculate gas mileage is to fill the tank, record the mileage, drive the truck, refill it and again note the mileage. Subtract the first mileage from the second, then divide by how many gallons it took to refill the tank. Just dumping gas in and guessing how many miles you can go on a tank is not even a little bit accurate. Link to comment Share on other sites More sharing options...
Chief Comanche Posted October 2, 2012 Author Share Posted October 2, 2012 I know that but... In other since you don't understand what my question. How many miles does people normally get out of a tank? Total miles not mpg..... I am only asking total miles per tank only under normal conditions.... The tank size is a 18.5 gallon tank. Link to comment Share on other sites More sharing options...
Minuit Posted October 2, 2012 Share Posted October 2, 2012 Depending on how and where you drive, these figures may be right. MJs certainly aren't hypermiler vehicles. I do most of my driving in the city and I get about 14 mpg and I have a bit of a lead foot. A tool like Fuelly will help in finding out how your mileage is. Also, I would double check all of the sensors and filters. Things like a dead o2 sensor can kill gas mileage and may or may not be noticeable. P.S. the fuel gauges in our trucks aren't always trustworthy. On mine, 3/4 = full. Link to comment Share on other sites More sharing options...
87Warrior Posted October 2, 2012 Share Posted October 2, 2012 It sounds to me like either your sending unit has fallen out of spec or the guys who installed your fuel tank bent the float rod. Even on a bad tank @ 10 mpg you should pull 180 miles, maybe 150 to the light. Link to comment Share on other sites More sharing options...
Jeepman Posted October 2, 2012 Share Posted October 2, 2012 So Far we only know that you have an 18.5G Tank and that you traveled 190 miles till the fuel light came on but you didn't say how many gallons you put back in the tank when you filled the Truck back up... The EPA says a Stock 92 MJ should get: 4.0L 2WD Auto MJ - 14 MPG City and 19 MPG HWY 4.0L 2WD Manual MJ - 16 MPG City and 20 MPG HWY 4WD 4.0L 2WD Auto MJ - 14 MPG City and 18 MPG HWY 4.0L 2WD Manual MJ - 15 MPG City and 20 MPG HWY So roughly 14MPG for a 18.5G tank should be somewhere around 250 miles so I would say your probably right on the money but without knowing how much fuel you put back in the tank it is only as guess based on the EPA Specs... Link to comment Share on other sites More sharing options...
cruiser54 Posted October 2, 2012 Share Posted October 2, 2012 How long is a piece of string? Link to comment Share on other sites More sharing options...
Chief Comanche Posted October 2, 2012 Author Share Posted October 2, 2012 Thanks jeepman, 87 warrior, and minuit for at least understanding the question. Jeepman you addressed it best as you have me an estimation of what a person can expect under normal driving conditions. The o2 sensors have been replaced fuel filters etc. to all that suggested changing those. The thing that had been problematic is the sending unit only. Cruiser54 I'm not sure why you even bothered full to answer as it wasn't remotely helpful by any stretch. Link to comment Share on other sites More sharing options...
Chief Comanche Posted October 2, 2012 Author Share Posted October 2, 2012 #jeepman, if I understand for a 92 4.0/ 4x4/ ax15 manual drive. When filling up with 18.5 gallon of gas one can expect to drive a total of 250 miles at most before the next possible fill up. That guess is estimation is without needing a properly working sending unit. Link to comment Share on other sites More sharing options...
Chief Comanche Posted October 2, 2012 Author Share Posted October 2, 2012 #jeepman, if I understand for a 92 4.0/ 4x4/ ax15 manual drive. When filling up with 18.5 gallon of gas one can expect to drive a total of 250 miles at most before the next possible fill up. That guess is estimation is without needing a properly working sending unit. Link to comment Share on other sites More sharing options...
mountainman Posted October 2, 2012 Share Posted October 2, 2012 this post makes me feel lucky. :) i get 500 to a tank on road trips. In the city i don't ever calculate cause it won't ever be the same twice and i do like to feel that 4.0 power each day when going places so ill stretch her legs on out to almost 5k rpm before i shift. But my avg in town is usually 190 to half a tank. 23.5 gallon tank. Gas light? what is that. lol. Link to comment Share on other sites More sharing options...
foreman1063 Posted October 3, 2012 Share Posted October 3, 2012 I get around 19 MPG, mixed highway and city driving. I get slightly better oil MPG but not much, ol Leaky :yes: Link to comment Share on other sites More sharing options...
Eagle Posted October 3, 2012 Share Posted October 3, 2012 I know that but... In other since you don't understand what my question. How many miles does people normally get out of a tank? Total miles not mpg..... I am only asking total miles per tank only under normal conditions.... The tank size is a 18.5 gallon tank. I understand what you're asking but the question has no valid answer. First, only the shortbed has that tank size, so owners of longbeds are disqualified. Second, no two gas gauges read exactly the same, so if I refill when it hits the 1/4 mark and you refill when it hits the 1/4 mark, it's almost guaranteed that both tanks WON'T take the same amount to fill. Same applies to the warning light -- when it turns on is not scientifically reproducible from one truck to the next. Link to comment Share on other sites More sharing options...
Eagle Posted October 3, 2012 Share Posted October 3, 2012 #jeepman, if I understand for a 92 4.0/ 4x4/ ax15 manual drive. When filling up with 18.5 gallon of gas one can expect to drive a total of 250 miles at most before the next possible fill up. That guess is estimation is without needing a properly working sending unit. ??? My '88 was still getting about 18 MPG last time I checked the mileage. It's a shortbed, so figure 18 gallons time 18 MPG and a tank (if I chose to run it down) would take me about 324 miles. Link to comment Share on other sites More sharing options...
FrankTheDog Posted October 3, 2012 Share Posted October 3, 2012 My light comes on around 280 mile or so. I get between 450 and 480 a tank. Link to comment Share on other sites More sharing options...
FrankTheDog Posted October 3, 2012 Share Posted October 3, 2012 Seeing how my gas gauge and low fuel light are so inaccurate I use the trip meter and calculate my mileage and I get between 18.5 general driving around and up to 22 on trips. Trying to guess how far you can go by your gas gauge is foolish. With our XJ's we refuel at 300 miles and with the MJ it's around 380-400. XJ's have 20 gallon tanks. My MJ has 23.5. Quite simple really. Link to comment Share on other sites More sharing options...
Chief Comanche Posted October 3, 2012 Author Share Posted October 3, 2012 Eagle thanks for the added information. I am and have been filling up and only using my trip meter to track mileage but i have yet to completely run the truck until bone dry as I don't want to carry a gas can just in case. I explained that the fuel sending until is not accurate or even reliable due to showing empty at only 160 miles following a fill up. So I have been wanting to know how far I could travel before completely running out of gas.... Just Ann idea not looking for a scientific explanation. Link to comment Share on other sites More sharing options...
Keyav8r Posted October 3, 2012 Share Posted October 3, 2012 Chief Comanche - I think you may have missed the point that several people were trying to make regarding your " miles per tank" question. In your second post you stated that the (low fuel) light came on at 168 miles and the gauge registered empty. You didn't tell us if you filled up at that point or later and didn't tell us how much gas you put in when you filled up. Then you do the mileage math by dividing the 168 miles (when the light came on) by 18.5 gallons (a full tank) for a mileage of 9.08 MPG - which is incorrect. The 168 miles should have been divided by the number gallons you put in at that point. Or, the number of miles you drove between a full tank and a fill-up should be divided by the number of gallons at that fill- up. The resulting MPG figure would then be multiplied by 18.5 (tank size) to give you YOUR estimated number of miles per tank. Using other people's MPG figures to calculate your full tank range is of no value Your range will be determined by your MPG. In his first post Cruiser54 suggested the two most likely causes for an erroneous fuel gauge reading and said to calculate your MPG by dividing miles driven by fuel burned, which is what almost everyone else said but your posts didn't indicate that you picked up on. I think his second post was a tongue in cheek comment on the whole measuring issue. I don't know how long you've been a member, but in the short time I've been a member I've noted that Cruiser54 is one of a group of very knowledgable members who are very helpful to us MJ neophytes. The second thing I've noted is that courtesy is the standard in all discourse on this forum, even when there is a disagreement or misunderstanding. Link to comment Share on other sites More sharing options...
Chief Comanche Posted October 3, 2012 Author Share Posted October 3, 2012 Keyav8r I totally understand what everyone said. However, the question was total miles to a tank of gas. A 18.5 gallon gas tank. And when asking that question, one can assume the tank would be full not 9.6, 10,or 15. A full task of 18.5 gallons. I did not want to know miles per gal. Link to comment Share on other sites More sharing options...
Chief Comanche Posted October 3, 2012 Author Share Posted October 3, 2012 Cruiser 54 if it appeared that I was being disrespectful or abrasive, I would like to solicit my apologies to you and any other that feels that way. I only wanted to know what other people had gotten in total miles driven not miles per gal. Link to comment Share on other sites More sharing options...
Chief Comanche Posted October 3, 2012 Author Share Posted October 3, 2012 Cruiser 54 if it appeared that I was being disrespectful or abrasive, I would like to solicit my apologies to you and any other that feels that way. I only wanted to know what other people had gotten in total miles driven not miles per gal. Link to comment Share on other sites More sharing options...
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