rworks Posted February 9, 2009 Share Posted February 9, 2009 87 shortbed MJ has the tiny stock gas tank. I'd like to get a bigger tank and since I figure finding one in an MJ is gonna be a task, can anyone give me some places to look for a new replacement? I was thinking JC Whitney (or the equivalent) might have something? Ideas? Link to comment Share on other sites More sharing options...
Pete M Posted February 9, 2009 Share Posted February 9, 2009 There was only one size tank available under shortbeds (18 gal) and I only know of stock-size replacements. :( Link to comment Share on other sites More sharing options...
LEAD_NOT_FOLLOW Posted February 9, 2009 Share Posted February 9, 2009 There was only one size tank available under shortbeds (18 gal) and I only know of stock-size replacements. :( If that is true than I find this info (directly from Jeep) interesting... But I also find it interesting that they say the MJ was built in '84 and '85 as well... :wavey: I can however confirm that my SWB '88 is only the 13.5 gallon one. So I'd venture to say that a good conversion for the pre '88 SWB MJ's would be an '89+ SWB tank. Link to comment Share on other sites More sharing options...
rworks Posted February 9, 2009 Author Share Posted February 9, 2009 There was only one size tank available under shortbeds (18 gal) and I only know of stock-size replacements. :( Then mine must be special, since it only takes a little over 13 gallons. Link to comment Share on other sites More sharing options...
mvusse Posted February 9, 2009 Share Posted February 9, 2009 I have an 87 with the 4.0. It has a 23.5 gallon tank instead of 13.5 listed. That is the optional larger tank. The base lwb tank is listed in my manual as 16 gallons and the swb only had an 18.5 gallon tank available, again straight from my manual. Link to comment Share on other sites More sharing options...
aemsee Posted February 9, 2009 Share Posted February 9, 2009 My 87 only has the 13.5 gal tank. As did my 88. Larger would be SWEET!! Link to comment Share on other sites More sharing options...
Pete M Posted February 9, 2009 Share Posted February 9, 2009 Guess I forgot about that one. :doh: Serves me right for not checking my facts first. :shake: Link to comment Share on other sites More sharing options...
Pete M Posted February 9, 2009 Share Posted February 9, 2009 I've now double checked my numbers with the dealership brochures, and there's no mention in any year of a shortbed fuel tank other than the 18 gal. Link to comment Share on other sites More sharing options...
Pete M Posted February 9, 2009 Share Posted February 9, 2009 My 87-90 Jeep parts catalog also only mentions the 16, 18 and 23.5 gal tanks. :hmm: Any of you guys with the 13.5 ever run out of gas? Link to comment Share on other sites More sharing options...
rworks Posted February 9, 2009 Author Share Posted February 9, 2009 My 87-90 Jeep parts catalog also only mentions the 16, 18 and 23.5 gal tanks. :hmm: Any of you guys with the 13.5 ever run out of gas? I've never run out because I pay veeeeeery close attention to the tiny gas gauge. Trust me, the 13.5 gallon tank existed; you've seen that already from 3 posters on this thread. Somewhere I've got the build sheet. I'll look for it after work today. Link to comment Share on other sites More sharing options...
Pete M Posted February 9, 2009 Share Posted February 9, 2009 Can you crawl underneath and take some measurements? Link to comment Share on other sites More sharing options...
mjeff87 Posted February 9, 2009 Share Posted February 9, 2009 I've got the tiny one in my '87 too. Even though my sender is a bit whacky (HO on a Renix that reads backwards), and was a little off even when it was stock, the most I've ever been able to stuff into it when close to "E" is 11.5 gallons. Jeff Link to comment Share on other sites More sharing options...
johnj92131 Posted February 9, 2009 Share Posted February 9, 2009 Check on Ebay. You will find several sellers of new, replacement tanks for about $75 or so. I "think" (but do not know) there is a difference in venting over several different years. My 91 long bed has the 23.5 gal tank as standard equipment per the manual and per the factor window sticker. 91 and 92 short beds had an 18 gallon tank. Link to comment Share on other sites More sharing options...
rworks Posted February 9, 2009 Author Share Posted February 9, 2009 Somewhere I've got the build sheet. I'll look for it after work today. Went looking for the build sheet, but I was mistaken. I have the dealer's invoice, which is different and doesn't have the gas tank on there. Link to comment Share on other sites More sharing options...
rworks Posted February 9, 2009 Author Share Posted February 9, 2009 Can you crawl underneath and take some measurements? OK, took measurements. May be off an inch in all three dimensions. 27Lx15Wx12H A quick calculation from the intertoob tells me that would hold about 21 gallons. Which still doesn't explain why I've run it waaaaay past the yellow light and still never got more than 13.1 gallons in it. Link to comment Share on other sites More sharing options...
mvusse Posted February 9, 2009 Share Posted February 9, 2009 I'm guessing when you actually run it dry, you will find it either reads below empty, or more likely it will read empty anywhere between 0 and 4 or 5 gallons of gas left. Link to comment Share on other sites More sharing options...
Pete M Posted February 9, 2009 Share Posted February 9, 2009 Or maybe it's not fully filling up? :hmm: Link to comment Share on other sites More sharing options...
rworks Posted February 9, 2009 Author Share Posted February 9, 2009 Or maybe it's not fully filling up? :hmm: Nah, I'm a habitual topper offer. Gassing up isn't finished until the gas is foaming up out of the filler neck. (yes, I know that isn't the right way to tell if its full) I guess the sender could be reading bad. Maybe I'll just toss the gas can in the back and run until she's dry, then fill and see what it takes. Link to comment Share on other sites More sharing options...
fiatslug87 Posted February 10, 2009 Share Posted February 10, 2009 This information is directly from the three owner's manuals: 1988: Long Bed 16 gallon standard, 23.5 gallon optional, Short Bed 18.5 gallon 1989: Long Bed 23.5 gallon, Short Bed 18.5 gallon 1990: Long Bed 23.5 gallon, Short Bed 18.5 gallon Link to comment Share on other sites More sharing options...
mvusse Posted February 10, 2009 Share Posted February 10, 2009 My 87 manual concurs with the 88 manual. Link to comment Share on other sites More sharing options...
ratrapp Posted February 10, 2009 Share Posted February 10, 2009 my 88 has the 23.5 gallon tank as well.the smaller tanks used 2 straps to hold it up where the bigger used 3 straps.funny thing is that before i replaced my tank is when the gas light came on it would have 4-5 gallons left.after i replaced the tank it comes on when there is only 1-2 gallons left. Link to comment Share on other sites More sharing options...
Eagle Posted February 10, 2009 Share Posted February 10, 2009 The 13.5 gallon capacity was in early base model Cherokees. I don't think it was ever in the MJ -- the tanks are totally different. Unless you had a build sheet run the day the vehicle was purchased, you really can't trust them too much. Chrysler apparently recycled some of the codes, so running a build sheet on an older XJ or MJ results in some eye-opening option listings that were never available in the year of the vehicle. Link to comment Share on other sites More sharing options...
JOMJ87 Posted February 10, 2009 Share Posted February 10, 2009 I ran my 87 SWB out alot cause i don't look at it and only got 13 or so back into it. Cole Link to comment Share on other sites More sharing options...
Pete M Posted February 10, 2009 Share Posted February 10, 2009 Can you take some measurements of the tank? Link to comment Share on other sites More sharing options...
reson46 Posted February 10, 2009 Share Posted February 10, 2009 My suspicions are that all the MJ tanks are the same size. The capacity difference is determined by the vent location. I know on YJs there was an option for larger capacity. The tanks were the same size, but with the smaller capacity was installed a vent tube extension that extended lower in the tank. This prevented filling the tank past the lowered vent tube level. If you paid extra for the larger capacity option they left the extension off allowing you to fill the tank more. :roll: I would guess they did the same thing with MJs. This would have been a lot cheaper than building two different sizes of tanks. One of these days I want to drop the tank to confirm this and reroute the vent tube for more capacity. Willy Link to comment Share on other sites More sharing options...
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