Kickin’Chicken Posted January 29, 2018 Share Posted January 29, 2018 Is a friend indeed...... I know I'm wearing out my welcome with all the threads I've started but this one is for my friend. He has a 1984 cj7 and just put a 7120 head from a '95 zj on his jeep. He also has the intake and exhaust as well as the harness. He got a crank position kit from HESCO and installed it on the balancer. Anyway, I went down to his shop most of Saturday night trying to help him get it to crank to no avail. The fuel pump turns on for a few seconds then shuts off and the coil gets 13 volts for a fraction of a second then drops to 2.6 volts. I'm thinking it has something to do with anti-theft or imobilizer function. Is there a way to bypass the imobilizer/security system? tia here's a pic for those that want to see what it looked like. Link to comment Share on other sites More sharing options...
Jeep Driver Posted January 29, 2018 Share Posted January 29, 2018 Quote The fuel pump turns on for a few seconds then shuts off and the coil gets 13 volts for a fraction of a second then drops to 2.6 volts. It had a 2.5 in it, didn't it? Link to comment Share on other sites More sharing options...
Jeep Driver Posted January 29, 2018 Share Posted January 29, 2018 Disregard my question, I see now what he did. Was the original 6 cyl carburated? Link to comment Share on other sites More sharing options...
Kickin’Chicken Posted January 29, 2018 Author Share Posted January 29, 2018 36 minutes ago, Jeep Driver said: Disregard my question, I see now what he did. Was the original 6 cyl carburated? Yes. He had the factory carb and constantly trying to fix it. Link to comment Share on other sites More sharing options...
Jeep Driver Posted January 29, 2018 Share Posted January 29, 2018 There is a thread here somewhere we'll have to find it regarding the 2.5 fuel pump he has the same setup on the carburated 6-cylinder when you turn the key on the pump is energized for 2 to 3 seconds and then shuts off when you turn the key to start the pump is energized again he will have to overcome this problem the reason it shuts off when the key ignition is on in the engine is not running is so you don't flood the engine the other thing he'll have to do is swap out to a 4.0 fuel pump the fuel pump in his Jeep currently is only good for 14 lb of pressure Link to comment Share on other sites More sharing options...
Jeep Driver Posted January 29, 2018 Share Posted January 29, 2018 If the photograph you provided is current the first thing I see are ground wires not connected I cannot speak to the status if his ignition system I have no idea I have no idea what if he's trying to combine two different systems to make it work I have no idea it looks like a rat Nest to me it's just something he's going to have to work through Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted January 29, 2018 Share Posted January 29, 2018 The 84 was carbureted, was it mechanical or electric fuel pump. From what I can tell it’s a mess, look like a mid 90s intake and injection system, to make the 90s engine management work he will need CPS ( in the bell housing 1995) and HO distributor (cam sensor) and fuel pressure of something like 40 lb.Carbureted systems or like 3 to 6 lb.Going to need the 1995 computer too. And maybe alternator since the computer controls it, maybe it is not really necessary don’t know. Easiest solution is grab the harness and computer from a working HO 4.0 91-95. Or aftermarket computer and harness.Simplest set up is carbureted with no computer, eliminate non essential wiring.Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted January 29, 2018 Share Posted January 29, 2018 I read the OP again, the 95 4.0 need the cam reading to spark. So the 95 distributor might fix it. If it’s anti-theft their might be away to disable it but I’d try to source a PCM that doesn’t have anti-theft. Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
Kickin’Chicken Posted January 30, 2018 Author Share Posted January 30, 2018 3 hours ago, Green Mesa XJ said: I read the OP again, the 95 4.0 need the cam reading to spark. So the 95 distributor might fix it. If it’s anti-theft their might be away to disable it but I’d try to source a PCM that doesn’t have anti-theft. Sent from my iPhone using Tapatalk Pro It has an aftermarket fuel pump with '95 distribution. And we think the imobilizer is the problem as well. If he gets an xj ecm, will the zj harness mate up to it? Link to comment Share on other sites More sharing options...
Jeep Driver Posted January 30, 2018 Share Posted January 30, 2018 What imobilizer? I don't think any '95 Jeep had a chip key? Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted January 30, 2018 Share Posted January 30, 2018 Those pcm are similar but I don’t know of anyone swapping XJ for ZJ pcm. As I recall there was early security in the grand Cherokee. Not sure how it worked, the same era Toyota security was door lock based, no fob control. If anything but the drivers door unlocked first the alarm would go off and the car was disabled until it was reset. Radio had some lame security code thing too. But that’s Toyota not sure how the early jeep security worked or how to bypass it Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
Green Mesa XJ Posted January 30, 2018 Share Posted January 30, 2018 Here is s link talking about ZJ security might be helpful http://www.jeepforum.com/forum/f13/security-system-bypass-169865/#/topics/169865Sent from my iPhone using Tapatalk Pro Link to comment Share on other sites More sharing options...
Kickin’Chicken Posted January 31, 2018 Author Share Posted January 31, 2018 On 1/29/2018 at 6:45 PM, Green Mesa XJ said: Here is s link talking about ZJ security might be helpfulhttp://www.jeepforum.com/forum/f13/security-system-bypass-169865/#/topics/169865 Sent from my iPhone using Tapatalk Pro Thanks! Link to comment Share on other sites More sharing options...
Eagle Posted February 1, 2018 Share Posted February 1, 2018 On 1/29/2018 at 8:53 AM, Kickin’Chicken said: Anyway, I went down to his shop most of Saturday night trying to help him get it to crank to no avail. The fuel pump turns on for a few seconds then shuts off and the coil gets 13 volts for a fraction of a second then drops to 2.6 volts. So you're saying the starter doesn't have power? Or the starter has power but doesn't turn the engine? What's the problem you're trying to solve? Link to comment Share on other sites More sharing options...
Kickin’Chicken Posted February 1, 2018 Author Share Posted February 1, 2018 6 hours ago, Eagle said: So you're saying the starter doesn't have power? Or the starter has power but doesn't turn the engine? What's the problem you're trying to solve? It turns over but it's not getting a spark. The coil is getting 12+ volts for a fraction of a second then drops to 2.6 volts. Fuel pump runs for 3 seconds then stops. He wired the ecm and sensors up with '95 harness and left the CJ harness in tact. He is sending ignition power to the computer via CJ harness' electronic ignition wires coming thru the firewall just above the brake booster (the CJ electronic ignition has been removed.) Anyway, it seems the security system is in the body control module and the BCM is not sending an "all clear" signal to the ECM. He ordered a new ECM that will (hopefully) have no memory of the old BCM and will (hopefully) work. I will keep all of you posted as I have a cj7 project of my own and want to do a similar head swap on mine. Link to comment Share on other sites More sharing options...
Eagle Posted February 1, 2018 Share Posted February 1, 2018 1 hour ago, Kickin’Chicken said: It turns over but it's not getting a spark. The coil is getting 12+ volts for a fraction of a second then drops to 2.6 volts. Fuel pump runs for 3 seconds then stops. He wired the ecm and sensors up with '95 harness and left the CJ harness in tact. He is sending ignition power to the computer via CJ harness' electronic ignition wires coming thru the firewall just above the brake booster (the CJ electronic ignition has been removed.) Anyway, it seems the security system is in the body control module and the BCM is not sending an "all clear" signal to the ECM. He ordered a new ECM that will (hopefully) have no memory of the old BCM and will (hopefully) work. I will keep all of you posted as I have a cj7 project of my own and want to do a similar head swap on mine. Your opening post said it doesn't crank. Turning over is cranking. So apparently your problem is that is DOES crank, but it doesn't fire. If the problem is the security system, I don't think the new ECM will solve the problem, since the problem originates in the BCM, but please keep us posted with results. If it were mine, I'd go back to the CJ electronic ignition and start driving. Link to comment Share on other sites More sharing options...
Kickin’Chicken Posted February 1, 2018 Author Share Posted February 1, 2018 27 minutes ago, Eagle said: Your opening post said it doesn't crank. Turning over is cranking. So apparently your problem is that is DOES crank, but it doesn't fire. If the problem is the security system, I don't think the new ECM will solve the problem, since the problem originates in the BCM, but please keep us posted with results. If it were mine, I'd go back to the CJ electronic ignition and start driving. Thanks for your response. My bad on the "crank" communication. If he uses the cj electronic ignition would he also have to use the cj distributor? And how will the computer detect/adjust for spark? Link to comment Share on other sites More sharing options...
Eagle Posted February 1, 2018 Share Posted February 1, 2018 3 hours ago, Kickin’Chicken said: Thanks for your response. My bad on the "crank" communication. If he uses the cj electronic ignition would he also have to use the cj distributor? And how will the computer detect/adjust for spark? He wouldn't need the computer to adjust for spark. The distributor does it. What was arguably the first automobile dates all the way to 1808. The first vehicles that were more or less practical came along in 1870. That means we managed to have internal combustion engines driving cars for more than 100 years before some genius decided it was a good idea to use computers to control them. We have a member here who is running his MJ with a distributor from a Jeep 4.2L engine. It can be done. The question is whether the computer will handle the injectors without a signal from the immobilizer circuit. Link to comment Share on other sites More sharing options...
DirtyComanche Posted February 1, 2018 Share Posted February 1, 2018 Since this harness/ECM was out of a ZJ, I'd go ask on MallCrawlin. Otherwise you're just going to get more advice like that ^^^. Link to comment Share on other sites More sharing options...
Sir Sam Posted February 2, 2018 Share Posted February 2, 2018 It's possible that security system is the problem. Maybe an ECU from an XJ without security would be a good test? I'm not sure how different the ECU pinouts are between the ZJ and XJ. This may not be helpful now, but if I were going through this exercise I would have gone with a 98-99 engine harness, ECU, and dizzy. The OBDII computer supports much more troubleshooting abilities. Some of these might still be available over the CCD bus if you had access to a DRBIII. Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 2, 2018 Share Posted February 2, 2018 From what I could find........ The BCM is a separate box, if you have a BCM you should know you have a BCM. If you have a BCM and you know you have a BCM, why in the world would you choose that model harness to begin with? No, another ECM will not fix the problem. And no, you will not be able to combine the '84 ignition with the '95 ignition. You'll have to wire the '95 as a stand-alone ignition........or..........? As I stated, looks like a cluster, owner appears to be chasing his tail on this. Link to comment Share on other sites More sharing options...
Eagle Posted February 2, 2018 Share Posted February 2, 2018 The solution is probably to rip out that entire rat's nest of wiring and start over from a clean slate. The Mopar Performance Catalog used to sell a complete fuel injection conversion for the carbureted YJs. It was basically the engine harness, fuel injection, and ECU from a 95 Wrangler, packaged as a stand-alone system. Something like that is what your friend needs. He already has the manifolds, the injection, and the throttle body. He needs the harness and the computer. (And maybe the fuel pump.) Time to hit the junkyards. http://www.fourwheeler.com/how-to/129-0309-efi-fuel-injection-258ci-jeep/ Link to comment Share on other sites More sharing options...
Sir Sam Posted February 2, 2018 Share Posted February 2, 2018 If he wants to start over with newer XJ fuel injection I can advise. The 98/99 harness makes for a pretty clean standalone option. Link to comment Share on other sites More sharing options...
Kickin’Chicken Posted February 2, 2018 Author Share Posted February 2, 2018 On 2/1/2018 at 10:56 PM, Sir Sam said: If he wants to start over with newer XJ fuel injection I can advise. The 98/99 harness makes for a pretty clean standalone option. Thanks. I'll use that on mine. My friend has his running now. All it needed was a new computer. On 2/1/2018 at 10:44 PM, Eagle said: The solution is probably to rip out that entire rat's nest of wiring and start over from a clean slate. The Mopar Performance Catalog used to sell a complete fuel injection conversion for the carbureted YJs. It was basically the engine harness, fuel injection, and ECU from a 95 Wrangler, packaged as a stand-alone system. Something like that is what your friend needs. He already has the manifolds, the injection, and the throttle body. He needs the harness and the computer. (And maybe the fuel pump.) Time to hit the junkyards. http://www.fourwheeler.com/how-to/129-0309-efi-fuel-injection-258ci-jeep/ All he needed was a new computer with no memory of the old BCM. It runs now On 2/1/2018 at 7:29 PM, Jeep Driver said: And no, you will not be able to combine the '84 ignition with the '95 ignition. It needed a new ecm. Runs fine now. Link to comment Share on other sites More sharing options...
Kickin’Chicken Posted February 2, 2018 Author Share Posted February 2, 2018 16 hours ago, DirtyComanche said: Otherwise you're just going to get more advice like that ^^^. LOL!!! Some of these guys are trying too hard to tell you how something WON'T work to think of how it will. And some simply don't have a clue what they're talking about. Link to comment Share on other sites More sharing options...
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