steve88mj Posted April 3, 2013 Share Posted April 3, 2013 I need to know what fuel pump I need to buy asap the truck has the complete HO swap I got the truck on trade and the fuel pump on it is leaking very bad out of the elbows that the rubber line clamps to the assembly outside of the tank because of rust. Can I just buy a HO Cherokee one or? The old one looks like it was cut and tac welded together from two different pumps. My gas gauge doesn't work right either? The metal lines that come out of the HO pump on the outside has one large one and one smaller one. Mine just has two of the same size that come out and straight up 90 degrees. The HO just sticks straight out. Anybody know what I need to do? Link to comment Share on other sites More sharing options...
steve88mj Posted April 3, 2013 Author Share Posted April 3, 2013 Auto parts stores said ho mj fuel pumps are discontinued? Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted April 3, 2013 Share Posted April 3, 2013 Check Rock Auto (rockauto.com) Link to comment Share on other sites More sharing options...
87manche1 Posted April 3, 2013 Share Posted April 3, 2013 I'm sure u mean sender right? Could silver braze to fix Link to comment Share on other sites More sharing options...
steve88mj Posted April 3, 2013 Author Share Posted April 3, 2013 I need the entire assembly not just the pump itself so yes I need the sending unit Link to comment Share on other sites More sharing options...
steve88mj Posted April 3, 2013 Author Share Posted April 3, 2013 Someone already put a band aid on it once I was going to try to patch the leak until I saw that rock auto doesn't have one listed nor any part stores. Link to comment Share on other sites More sharing options...
steve88mj Posted April 3, 2013 Author Share Posted April 3, 2013 I have a good renix fuel pump from an MJ will that work? Someone told me an XJ would work but the gas gauge will work backwards? Link to comment Share on other sites More sharing options...
mjeff87 Posted April 3, 2013 Share Posted April 3, 2013 Yes, a Renix fuel pump assembly will work on an HO engine and gauge cluster, and visa-versa. I have been running an HO pump assembly in my Renix for about three years now with no problems, other than the fuel gauge reading backwards and about 1/4" tank off. I just have to remember that when the needle is reading "full", I'm just about out of gas. Jeff Link to comment Share on other sites More sharing options...
jimoshel Posted April 3, 2013 Share Posted April 3, 2013 Yes, a Renix fuel pump assembly will work on an HO engine and gauge cluster, and visa-versa. I have been running an HO pump assembly in my Renix for about three years now with no problems, other than the fuel gauge reading backwards and about 1/4" tank off. I just have to remember that when the needle is reading "full", I'm just about out of gas. Jeff Why not just cut and switch the two wires by the tank? Link to comment Share on other sites More sharing options...
HOrnbrod Posted April 4, 2013 Share Posted April 4, 2013 Why not just cut and switch the two wires by the tank?Won't work. Since the variable voltage output to the fuel gauge comes off the potentiometer's slider terminal, to change output polarity to the gauge you need to switch the input voltage from one pot leg to the other. Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted April 4, 2013 Share Posted April 4, 2013 Why not just cut and switch the two wires by the tank?Won't work. Since the variable voltage output to the fuel gauge comes off the potentiometer's slider terminal, to change output polarity to the gauge you need to switch the input voltage from one pot leg to the other. So, can that be done to correct the issue? Link to comment Share on other sites More sharing options...
87manche1 Posted April 4, 2013 Share Posted April 4, 2013 Supposed to be another terminal but ive seen a few posts were it ruined the pot. All together All the sender does is say at full u have 150 ohm empty is 25. switching the wires + wire to the neg and neg to + does nothing plus ur fuel pump shares the same grounding. Link to comment Share on other sites More sharing options...
HOrnbrod Posted April 4, 2013 Share Posted April 4, 2013 Yes, I've bench tested it using an HO sender and Renix sender. The gauge will move in the right direction and be close to accurate, but won't be spot on because of the difference in values between the renix and HO potentiometers. As Jeff stated above. Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted April 4, 2013 Share Posted April 4, 2013 So, next question is, why the hell did they make the MJ and XJ MPFI fuel pumps different?? :doh: That's enough to drive someone crazy. They ought to be interchangeable... :fs1: Link to comment Share on other sites More sharing options...
87manche1 Posted April 4, 2013 Share Posted April 4, 2013 Hornbird jeff stats his works backwards how would u get a 91+ to work correctly pics of how? Link to comment Share on other sites More sharing options...
HOrnbrod Posted April 4, 2013 Share Posted April 4, 2013 Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted April 4, 2013 Share Posted April 4, 2013 So moving that blue wire to the other side of the sweep will correct the backwards reading? Link to comment Share on other sites More sharing options...
HOrnbrod Posted April 4, 2013 Share Posted April 4, 2013 http://comancheclub.com/topic/15047-ho-fuel-sending-unit/?hl=leg&do=findComment&comment=153158 Link to comment Share on other sites More sharing options...
87manche1 Posted April 4, 2013 Share Posted April 4, 2013 Interesting thanks don my 96 xj sender does not have it Link to comment Share on other sites More sharing options...
HOrnbrod Posted April 4, 2013 Share Posted April 4, 2013 The 96 sender is modular but still has a float that moves a potentiometer slider. Don't know if you can get to the pot terminals though..... Link to comment Share on other sites More sharing options...
87manche1 Posted April 4, 2013 Share Posted April 4, 2013 No one side doesnt have a tracer the arm would hit solder Link to comment Share on other sites More sharing options...
87manche1 Posted April 4, 2013 Share Posted April 4, 2013 http://www.newjeepparts.com/seccat/comanche-mj-828/1989/sending-unit-31427/6/31427/ Link to comment Share on other sites More sharing options...
mjeff87 Posted April 4, 2013 Share Posted April 4, 2013 I would most definately call them or ask to see a picture of what they are offering before ordering that. Odds are that they are XJ sending units, not actual MJ ones. Jeff Link to comment Share on other sites More sharing options...
87manche1 Posted April 4, 2013 Share Posted April 4, 2013 Yea it doesnt say really Link to comment Share on other sites More sharing options...
steve88mj Posted April 5, 2013 Author Share Posted April 5, 2013 It had a renix sending unit but the fuel pump part was pieced together from a 94 HO one. Whomever did it it looks like they took the gas gauge float assembly and cut it off and tac welded the other on there was some things done with the wiring too but I have no idea what I'm looking at never dealt with this issue until now and I have had 5 MJs 2 where HO I'm glad all the other sending units held up I was lucky because I happened to save a sending unit and had no idea you can't buy new ones. I will try to get a pic of the old sending unit so you can see what the guy did the gas gauge and everything worked fine? Link to comment Share on other sites More sharing options...
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