Minuit Posted May 7, 2021 Share Posted May 7, 2021 Neat video on the mechanical airbag system in '95 and '96 XJs: Link to comment Share on other sites More sharing options...
Virden Posted May 7, 2021 Author Share Posted May 7, 2021 Pretty sure this is ecu Having a hard time getting a pic of the other end of the cps So the part I need is a 96 cps for an xj correct? Also couple of terms I am unfamiliar with HO? Renix? What are those in reference to Thanks again Link to comment Share on other sites More sharing options...
Virden Posted May 7, 2021 Author Share Posted May 7, 2021 So what do I need to do to get me speedometer and gas gauge working Pretty sure my fuel pump is not right for the job It’s loud Link to comment Share on other sites More sharing options...
scaleless Posted May 7, 2021 Share Posted May 7, 2021 The fuel pump is normally loud. Renix Comanches have a ballast resistor in series with the fuel pump to make it quieter and I'm sure the previous owner threw it away when he made the swap. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted May 8, 2021 Share Posted May 8, 2021 You have an obd2 system which is a return less fuel system (and we can say with some certainty that you have all 96 Cherokee parts swapped in). If you have the original fuel sender and pump from the 89 (which you obviously do since the gas gauges reads backwards) then you have no fuel pressure regulator at all in the system. You pump will be begging for mercy since the only pressure relief it has is the pressure relief valve in the pump itself. You need to add a fuel pressure regulator in the fuel circuit and set it to the correct obd2 psi (seems like high 50’s or low 60’s psi iirc). Then replace your actual fuel pump (just the pump) with a 4.0 XJ/MJ pump. The pumps always make some noise but it’s pretty minimal. There may be a resistor for the fuel pump right near your brake booster on the drivers side inner fender that was added to reduce the pump noise. It does help somewhat but also isn't necessary. Get a fuel pressure regulator and connect the return line to it so you can get the fuel system working the right way. This is something that always gets missed with these obd2 swaps. To get you speedo working, you will need to connect the vehicle speed sensor which is located in the transfer case output (see pic). The speed sensor signal should go to both the ecu and the speedometer. If your jeep dies sometimes when coasting or when you come to a stop it’s normally the speed sensor that is not connected to the ecu. fuel gauge: you newer gauge cluster is meant to read 0-80ohms resistance but your sender is like a 2**-30 ohms. Look for a signal converter from Dakota digital or you could swap out the sending unit to one from a 91-92 MJ but they are very hard to find and are only available used. Auto parts stores will say they are available new but they are for a Cherokee XJ and don’t fit. The signal converter is the easiest way to go here. Link to comment Share on other sites More sharing options...
Virden Posted May 8, 2021 Author Share Posted May 8, 2021 Man I can’t thank all of you enough for shedding light on my Jeep!!! I had one 22 years ago and drove it back from Alaska. I sold it and regretted it every day for the last 20 years I finally got to a place were I could replace it This Jeep is mostly the same Shortbed , 4x4, 4.0 No stick but oh well Other was a chief this one a pioneer Level of happiness restored LOL Would you mind if I post pics of parts before I bought them to try and make sure I am getting the right thing I’d like to get good at vehicle repair as I plan to drive this back to Alaska one day Thanks again! Link to comment Share on other sites More sharing options...
ghetdjc320 Posted May 8, 2021 Share Posted May 8, 2021 Here is a good fuel gauge adapter interface option: https://www.tanksinc.com/index.cfm/page/ptype=product/product_id=748/category_id=184/mode=prod/prd748.htm Link to comment Share on other sites More sharing options...
Virden Posted May 8, 2021 Author Share Posted May 8, 2021 I’ll get it!!! Thanks Link to comment Share on other sites More sharing options...
Virden Posted May 9, 2021 Author Share Posted May 9, 2021 Is this a good fuel pump or is there a better one out there?https://www.quadratec.com/products/51306_0147.htm?gclid=EAIaIQobChMIt4urhLS88AIV4fbjBx1n-AmwEAQYASABEgLt1vD_BwE Link to comment Share on other sites More sharing options...
ghetdjc320 Posted May 9, 2021 Share Posted May 9, 2021 You just need the pump, not the whole sending unit. And the XJ sending units don’t fit MJ tanks. Link to comment Share on other sites More sharing options...
Virden Posted May 9, 2021 Author Share Posted May 9, 2021 Thanks! That’s good to know Link to comment Share on other sites More sharing options...
Virden Posted May 9, 2021 Author Share Posted May 9, 2021 Would this be what I need ? https://www.quadratec.com/products/51305_0016.htm?gclid=EAIaIQobChMIuvuBj7-98AIVyMqUCR1ZCwJqEAQYByABEgLPBvD_BwE Link to comment Share on other sites More sharing options...
ghetdjc320 Posted May 9, 2021 Share Posted May 9, 2021 No sending unit from an XJ will fit in your tank. This isn’t anything that quadratec will have. Here are some pump options: https://www.rockauto.com/en/catalog/jeep,1989,comanche,4.0l+242cid+l6,1181674,fuel+&+air,fuel+pump,6256 The newer XJ fuel system had a regulator that was in the fuel tank and only ran one fuel supply line to the engine at a preset psi. Your old MJ fuel system had a supply line and a return line going to the fuel rail. There was a pressure regulator on the fuel rail that set the pressure for the rail and allowed anything else to return to the tank. You are going to have to fab up something similar. You will need to find the correct fuel pressure for the obd2 system (96-01 XJ) and get an external adjustable fuel pressure regulator along with fittings and hoses. You need one with one inlet and two outlets. The inlet will be the feed from your pump. One outlet will be your fuel rail line that will need to have the pressure set (you’ll need a gauge for this). The other line will be a return line that will connect to your old return line (provided it’s still there and no plugged off somewhere). You may not need a new pump but running with no regulator will put undue strain on it. Let’s get a few more pics. Let’s see what your current sending unit looks like on the side of your fuel tank (just take a picture of it as is, no need to disassemble anything). Also, track the main fuel lie and the return fuel line and see what they did with the return line. My guess is that it has a cap on it somewhere but you’ll need to know for sure before you can order up any parts to modify things. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted May 9, 2021 Share Posted May 9, 2021 Looked up the fuel pressure spec for you and it should be around 50 psi at idle. That is a static fuel pressure and should not change on the obd2 systems. (On the 91-95 HO systems the fuel pressure regulator on the rail would change based on engine vacuum and the fue injection was programmed to run on this variable pressure. Not so on the obd2 engines. The ecu maps are based on a static pressure). Link to comment Share on other sites More sharing options...
Virden Posted May 10, 2021 Author Share Posted May 10, 2021 I’ll take the pics tomorrow! Thanks should I install this first? ? Haven’t order yet just trying to figure out what I need Much appreciated Link to comment Share on other sites More sharing options...
ghetdjc320 Posted May 10, 2021 Share Posted May 10, 2021 I’d say the fuel gauge is secondary to gettin it running right. Let’s see what the fuel system needs first. Just my $.02 Link to comment Share on other sites More sharing options...
Virden Posted May 10, 2021 Author Share Posted May 10, 2021 Ok sounds good! Link to comment Share on other sites More sharing options...
Eagle Posted May 10, 2021 Share Posted May 10, 2021 4 hours ago, Virden said: I’ll take the pics tomorrow! Thanks should I install this first? ? Haven’t order yet just trying to figure out what I need Much appreciated I'm not sure that adapter does what you need. There isn't a huge difference in the ohm range from the old system to the new system. Going from memory, I believe the old system was 0 to 80 ohms and the new system was 103 to 5 ohms. Gas gauges are only approximate anyway, so that may not be a big deal. The bigger issue you have is the reversed polarity, and the description of that doohickie doesn't tell me that it can address that. Link to comment Share on other sites More sharing options...
scaleless Posted May 10, 2021 Share Posted May 10, 2021 14 hours ago, Eagle said: The bigger issue you have is the reversed polarity, and the description of that doohickie doesn't tell me that it can address that. I agree, I'm also not sure if that device can reverse the sender output. Regardless, a circuit that would do exactly what you want is fairly trivial to make. Pretty sure I have everything I need to make this if you want me to ship you one. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted May 10, 2021 Share Posted May 10, 2021 The gas gauge is somewhat secondary to getting things running right I would say but I like that option as well Link to comment Share on other sites More sharing options...
Virden Posted May 11, 2021 Author Share Posted May 11, 2021 I am open to that idea Thanks! Here are the pics I can take more if I missed something Link to comment Share on other sites More sharing options...
ghetdjc320 Posted May 11, 2021 Share Posted May 11, 2021 That metal line that is disconnected was your old fuel return line. There is no visible fuel pressure regulator here at all. I’d mount a regulator rather near the tank or in the engine bay and plumb the return line back in. Where does that rubber hose go off the tank sender that is pointing up in the pics? I imagine it’s plugged somewhere. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted May 11, 2021 Share Posted May 11, 2021 And just to clarify, that module from Tanks does what you need. It can reverse the resistance of any sender to fit pretty much any gauge. It can even do exponential signal sweeps. Pretty neat little device. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted May 11, 2021 Share Posted May 11, 2021 There is one thing I am finding odd though. That sender is really clean. Almost like it’s new. Might be worth pulling to see what’s inside. Link to comment Share on other sites More sharing options...
Virden Posted May 11, 2021 Author Share Posted May 11, 2021 I’ll track down the rubber hose tomorrow what fuel regulater do I need? How hard to install? This truck came with part receipts I’ll see if there is one for the fuel sender and pump Could probably try and pull the tank this weekend how hard is that on a scale of one to ten? Link to comment Share on other sites More sharing options...
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