Strokermjcomanche Posted September 4, 2015 Share Posted September 4, 2015 Some background info : It's an 88 manual nv3550 with a 4.0 ( actually 4.7 stroker ) , 89 dash harness out of manual a 2.5 mj ,engine harness and all electronics from a manual 2 dr 90 xj . I've done 1-14 , 18 and 23 of Cruisers tips so far . New parts include mopar high altitude CPS, plugs , wires , cap , rotor , ICM , coil , knock sensor , 746 Bosch injectors , new battery cables , new supplemental ground wires ran , new ignition switch and adjusted properly . I'm getting 31 psi and 39 psi of fuel pressure . The engine cranks normally and fires but only runs for a second or two but then shuts down with no sputtering and can repeat this over and over with the same results . I've cleaned the ground behind the left tail light and swapped the fuel pump relay with other known good one . What should I check for next ? Maybe I've overlooked something but I've went over everything listed above . Thanks in advance . Link to comment Share on other sites More sharing options...
91Pioneer Posted September 4, 2015 Share Posted September 4, 2015 Did you try bypassing the resistor on the fender? Connect the two wires together. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted September 4, 2015 Author Share Posted September 4, 2015 Did you try bypassing the resistor on the fender? Connect the two wires together. Yes I did , and I forgot to mention it's a new mopar resistor too Link to comment Share on other sites More sharing options...
Crash Posted September 4, 2015 Share Posted September 4, 2015 If you hold the key between start and run does it continue running? I had that issue a couple different times. First was ignition switch, so I bypassed that with a toggle and push button start. Second time was the ballast resistor. From my understanding all the "new" ones are crap. I bypassed that as well and have zero issues. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted September 4, 2015 Author Share Posted September 4, 2015 If you hold the key between start and run does it continue running? I had that issue a couple different times. First was ignition switch, so I bypassed that with a toggle and push button start. Second time was the ballast resistor. From my understanding all the "new" ones are crap. I bypassed that as well and have zero issues. Just tried that now , all It did was grind the starter bendix in the flywheel with no change . Link to comment Share on other sites More sharing options...
91Pioneer Posted September 4, 2015 Share Posted September 4, 2015 Try bypassing the resistor anyway. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted September 4, 2015 Author Share Posted September 4, 2015 Try bypassing the resistor anyway. Already have ^^ . I wish it was that easy . Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted September 6, 2015 Author Share Posted September 6, 2015 So today I unplugged the plugs at the ignition switch and plugged them in to the extra switch I had and no change . Started checking at the fuel pump relay and something seems off . 90 xj wire colors 86 yellow wire getting constant power 30 red wire no power 87 orange wire getting ground 85 blk wire with orange trail , no ground or power until the test light is grounded on the battery and makes contact with this wire but is a very faint light and the relay clicks and still will not start . Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 6, 2015 Share Posted September 6, 2015 What's the equivalent of the HO ASD (Auto Shut Down) relay in the Renix stuff? Is there one or is there an anti-rollover relay? In the HOsw, the ASD relay sends a ground to the fuel pump relay when it senses the distributor shaft turning and allows the engine to start. Any such animal in the primitive Renix system? Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted September 6, 2015 Author Share Posted September 6, 2015 What's the equivalent of the HO ASD (Auto Shut Down) relay in the Renix stuff? Is there one or is there an anti-rollover relay? In the HOsw, the ASD relay sends a ground to the fuel pump relay when it senses the distributor shaft turning and allows the engine to start. Any such animal in the primitive Renix system? Should I have someone try to start the truck while I'm checking the wires at the relay ? I checked all these wires with the key both on and off . Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 6, 2015 Share Posted September 6, 2015 No idea for the Renix Adam. The only function in life for the HO ASD relay is to latch the fuel pump relay when the engine is cranking after it senses distributor shaft rotation. I don't know if a Renix has a similar setup, or even has an anti-rollover relay thats tied into the fuel pump circuit. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted September 6, 2015 Author Share Posted September 6, 2015 No idea for the Renix Adam. The only function in life for the HO ASD relay is to latch the fuel pump relay when the engine is cranking after it senses distributor shaft rotation. I don't know if a Renix has a similar setup, or even has an anti-rollover relay thats tied into the fuel pump circuit. I might as well try that tomorrow anyhow , it's worth a shot . Thanks for the reply . I don't know why the engine starts and then dies right away because the relay isn't getting any power at pin 30 Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted November 16, 2015 Author Share Posted November 16, 2015 Ok I'm still at this , I replaced the fuel pump with a Bosch 69302 . It had a Bosch pump in it and I believe it to be original pump being it had the factory part number on it . The rubber hose was gummed up and cracked and I thought it may have been the problem but it wasn't . Then I had a spare tail light harness and installed it to replace the one that had been hacked up for a trailer harness , still no change . I don't know what else it could be or what to check . I'm about ready to go locate another engine harness and replace it along with the extra dash harness I have . I have No problem admitting I suck at diagnosing electrical issues , I've starred at the FSM at it looks like hyroglifics to me . Any help is much appreciated , I'd like to have it running before the weather turns bad if possible . Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 16, 2015 Share Posted November 16, 2015 Try swapping out the Fuel Pump relay with the Power Latch relay. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted November 17, 2015 Author Share Posted November 17, 2015 Try swapping out the Fuel Pump relay with the Power Latch relay. I will when I get home . Thanks Don Link to comment Share on other sites More sharing options...
johnj92131 Posted November 17, 2015 Share Posted November 17, 2015 I suck at electrical diagnosis also. But I think you said the truck started, then when you let the key go back to the run position, the engine dies? So what is in the circuit when the starter is running (besides the starter/bendix/solinoid/etc) to keep the ignition firing? Sounds like something in the starter circuit keeps the ignition firing but when the key is in the run position the ignition is not firing (and the engine dies). Kind of sounds like there is an ignition run permissive that is AWOL when the key is in the run position? Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted November 17, 2015 Author Share Posted November 17, 2015 John : that's pretty much what happens . For those couple seconds that engine runs flawlessly , no backfiring/ sputtering etc . I have almost everything besides the harness replaced that deals with the ignition , so process of elimination points me in the same direction . I'm going to try the relay as Hornbrod suggested and see what other suggestions are mentioned and try them too . Thanks John . Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted November 17, 2015 Author Share Posted November 17, 2015 Another wasted day , replaced the fuel pump relay with no change . Then I pulled the dash and changed the dash harness with the extra one I had , no change . I'm exhausted . So what's the next step ? I guess look for another engine harness ? Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted November 23, 2015 Author Share Posted November 23, 2015 Well it lives , kind of . I took a jumper wire from the battery and ran it to where the 87 male terminal of the relay would go in and it fired right up . Runs great , but I'm still not getting any power at 30 ( it's a step forward) . This is the way the relay is supposed to behave right ? Do / can I just run new wires and call it done ? I'm not a fan of butchering the wiring and have it fail on me in the future .. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted December 23, 2015 Author Share Posted December 23, 2015 Update : Finally found the culprit , it was a fusible link at the ignition relay . One side tested good (green wire ) but the other wire(orange) covering was real flexible and pulled apart with ease . Put a new fusible link in and all is good . Now to see why the gauges are bouncing around when I try to use the turn signal . Thanks to all that gave advice / knowledge on this . Link to comment Share on other sites More sharing options...
89Commanche Posted January 2, 2023 Share Posted January 2, 2023 Hey Stroker, I think I’m having the exact problem you was. I can keep it running while holding the starter over, but acts like it’s starving of fuel when I let off the ignition. I jumped the fuel pump to a toggle switch to temporarily get me out of a bind. It worked and ran but very poorly. Replaced fuel pump relay but no luck there. Also new ignition switch. Could you please explain where you found that disable link for the ignition switch? Hoping it may be my problem! Thanks! Link to comment Share on other sites More sharing options...
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