brucecooner Posted June 28 Share Posted June 28 EDIT: If you got to this thread searching for why your Renix will crank but not start, or get no-starts at random, it might be the battery losing its juice. A new Group 34 battery (yes, it fits in an '88 tray) fixed my problem. --- I got a no start a few weeks ago, popped the hood and jiggled the C101 and it started right up. I wound up cleaning the connector (see elsewhere), but after a couple weeks got the no start again. Hmmm. Jiggled the connector, started. About a week later, no start again, and it did NOT seem to be the connector this time. No amount of futzing got it to start. Went out the other day to attempt to debug. Put the fuel pressure gauge on and turned key on, 32 psi. Put the spark plug light inline, had my son crank it so I could watch the light and lo and behold it was a bit of a rough start, but it did start. So now I'm thinking the connector was just a red herring (it did need cleaning though, it was a bit crusty). My suspicion is that it was just not starting randomly for some unrelated reason. Note, randomly. Whether it was starting or not probably had nothing to do with my jiggling and fiddling, and was related to some currently unknown condition. On one or two of these no start days, it cranked a few turns, then stopped cranking as I heard a thunk from below the floorboard, which made me think the starter was having a conniption, that may be unrelated though. Once it starts it purrs, maybe like a slightly asthmatic kitten, but there's no sign of trouble whatsoever. And it keeps running. Sunday I cleaned up some connections under the hood and since it started that day I took it out on a pleasure cruise, twenty or so miles, and it didn't miss a beat. The non-start seems to have gotten more prevalent since it began, so I may be looking at something that's on the way out. What kind of things would lead to a no-start, but NOT a no-run, condition? Is some sensor somewhere going out? Something in the ignition system unhappy (coil, etc.)? Link to comment Share on other sites More sharing options...
pizzaman09 Posted June 28 Share Posted June 28 I've got to imagine you should clean all your grounds , particularly the one by the dip stick tube. Link to comment Share on other sites More sharing options...
Gojira94 Posted June 28 Share Posted June 28 29-32psi sounds fine for a running engine, and it would probably start with some sputter that low at KOEO. But it'd be much better to see it in the 37-39psi range at KOEO. Unless you saw 32 some number of seconds after KOEO and it bled off a little before you observed it. x2 on cleaning and verifying grounds though. Cruiser54's fuel pump ground mod might help some as well, pretty quick and easy for the return benefit. And that brings to mind the ballast resistor. Might try bypassing that as part of secondary troubleshooting. Link to comment Share on other sites More sharing options...
brucecooner Posted June 28 Author Share Posted June 28 7 hours ago, pizzaman09 said: I've got to imagine you should clean all your grounds , particularly the one by the dip stick tube. I didn't mention in my post but I'm going around to various under-hood connections as I can. I've cleaned that ground by the dipstick last year, but will get it again as I get around under there. I've noticed a previous owner added an extra block-to-firewall ground strap, somebody knew about these types of things. 5 hours ago, Gojira94 said: 29-32psi sounds fine for a running engine, and it would probably start with some sputter that low at KOEO. But it'd be much better to see it in the 37-39psi range at KOEO. Unless you saw 32 some number of seconds after KOEO and it bled off a little before you observed it. x2 on cleaning and verifying grounds though. Cruiser54's fuel pump ground mod might help some as well, pretty quick and easy for the return benefit. And that brings to mind the ballast resistor. Might try bypassing that as part of secondary troubleshooting. That was after a few seconds. The injectors are a rebuilt set I put in a couple years ago (bought from someone cruiser recommended, not some random amz or ebay purchase), so I hope they're sealing well but I should check the KOEO instant pressure. The fuel pump might be old and tired, like a lot of other things on the truck. I've been meaning to add the FP ground mod, but it's been hot here lately, and laying on the pavement is like being on hot coals. Yeah I need to invest in a creeper, it would see a lot of use now that my son has an old F150. I've heard about the ballast resistor delete. I actually cleaned the connectors on mine the other day, but the best part is no part, one less thing to fail would be nice. Unfortunately I park it facing north in our driveway and the weather usually blows in from the west, meaning the driver's side hood bay and everything near that edge of the hood gets pretty wet. I obviously need to start backing it in the driveway so the rain blows in the other side for a change. Link to comment Share on other sites More sharing options...
fiatslug87 Posted June 28 Share Posted June 28 Test the CPS and look at the connections. Try jumping the fuel pump ballast resistor, driver side fender at the front. Also check the connections behind the driver kick panel. Mine was loose and would intermittently not start but if I slammed the door it would. Link to comment Share on other sites More sharing options...
brucecooner Posted June 29 Author Share Posted June 29 1 hour ago, fiatslug87 said: Try jumping the fuel pump ballast resistor, driver side fender at the front. Also check the connections behind the driver kick panel. Mine was loose and would intermittently not start but if I slammed the door it would. That's intriguing because I took my kick panel off a while back looking for rust in the floorboard (yep, need to do some scraping and sealing there) and I just left the kick panel off. So there's a good chance those connections have gotten brushed or knocked on. Are you referring to a specific fuel pump related connection down there or all of them? Link to comment Share on other sites More sharing options...
fiatslug87 Posted June 29 Share Posted June 29 I don’t recall what the connector looks like but the fuel pump wiring goes up that panel. Link to comment Share on other sites More sharing options...
brucecooner Posted July 17 Author Share Posted July 17 Man, I could NOT unplug the big gray connector behind the kick panel to check it out. But, nothing under there seems loose or disconnect-y. No luck yet figuring out my no start (got sick for a couple weeks), but I have been cleaning up various connectors under the hood, doesn't look like anything has ever been cleaned. I went to do the cruiser ignition coil tip.... https://cruiser54.com/?p=41 And found out my coil might be the original unit, and it looks a bit rough. Looks like it might have event gotten wet at some point. I cleaned up the contacts on it, but I have to wonder if should I just replace it based on visual inspection and apparent age. Also, the cradle the coil sits in on my '88 (ICU?) doesn't look quite like the one from cruiser's tip. Ugh, picture is backwards. Anyway, I have the little connectors for the two pins on the bottom of the coil, but I don't see the "pins" as indicated in the tip. Is there some contact surface here that I'm overlooking? Those little connectors I could see were really nasty so I cleaned them up and spritzed some electronics cleaner into both the plugs. I didn't bend them inward, need to go back in and do that. I'm moving towards the plugs from here. The contacts inside the distributor were completely oxidized so I cleaned all the surfaces in and on the dist. cap so everything was shiny, and the tip of the rotor inside. Of course, none of this fixed my no-start... But it was stuff that needed doing. I've checked the fuel rail pressure several times, it is pressurizing well enough. My next step is to put the spark light after the coil and see if that thing's putting out any juice. I doubt it will be that simple though. Link to comment Share on other sites More sharing options...
eaglescout526 Posted July 17 Share Posted July 17 This just occurred to me. Do you have the C101 and have you cleaned it? Link to comment Share on other sites More sharing options...
brucecooner Posted July 17 Author Share Posted July 17 31 minutes ago, eaglescout526 said: This just occurred to me. Do you have the C101 and have you cleaned it? I originally thought the C101 was the source of all my trouble, as I could jiggle it and then it would start. What was really happening was something else was failing intermittently and my jiggling wasn't actually affecting anything. But I did open up and clean the C101. Twice because I'm insane I guess. It was super nasty inside, and definitely needed a cleaning, but it's cleaned up and snug now. I plan to delete it when the weather cools off. I started at the air cleaner and have been going counter clockwise around the engine bay cleaning up the connectors I see. It's a clean truck, never got dirty, but it looks like none of the connectors have ever been unplugged and some of them are a bit crusty after nearly 40 years. Link to comment Share on other sites More sharing options...
eaglescout526 Posted July 17 Share Posted July 17 8 minutes ago, brucecooner said: originally thought the C101 was the source of all my trouble, as I could jiggle it and then it would start. What was really happening was something else was failing intermittently and my jiggling wasn't actually affecting anything. Ok. The only reason why I say this is once a year, every summer, ever since I cleaned it out in 2017-18, I’ll have an issue where she will run funny and the O2 circuit is the cause of her running funny till about 15 min of driving and it’ll clear up. So I’ll spend about an hour with some electrical contact cleaner and spray the hell out of both ends liberally until it’s clean or I’m satisfied with it and give her a start and see if my issue clears. I honestly think with how hot it gets out here, the stuff in the C101 is getting liquified and messing with the connection. Link to comment Share on other sites More sharing options...
fiatslug87 Posted July 17 Share Posted July 17 Have you tried jumping the fuel pump ballast resistor? Link to comment Share on other sites More sharing options...
brucecooner Posted July 17 Author Share Posted July 17 1 hour ago, eaglescout526 said: Ok. The only reason why I say this is once a year, every summer, ever since I cleaned it out in 2017-18, I’ll have an issue where she will run funny and the O2 circuit is the cause of her running funny till about 15 min of driving and it’ll clear up. So I’ll spend about an hour with some electrical contact cleaner and spray the hell out of both ends liberally until it’s clean or I’m satisfied with it and give her a start and see if my issue clears. I honestly think with how hot it gets out here, the stuff in the C101 is getting liquified and messing with the connection. "Liquified". Absolutely. When I first opened mine there was brown gunk inside, I'm pretty sure it was whatever rubbery stuff was originally in there that had long since turned to liquid. The brown gunk was everywhere, I sprayed e cleaner in both sides for a while until it mostly quit coming out. Then when I cleaned it the second time a bunch more came out. 1 hour ago, fiatslug87 said: Have you tried jumping the fuel pump ballast resistor? I remember someone mentioning that but the fuel pressure gauge says I'm at 32psi at key on so I hadn't considered the fuel system any further. I'll definitely jump across it next time I'm out there. As I understand it I can just delete the ballast and live with the slightly louder fuel pump. Does deleting the ballast affect the lifespan of the pump? I'd assume not since I think the resistor wasn't even on earlier models. A new ignition coil is $60 bucks from Napa, I'm seriously considering it. It would be just firing the parts cannon for sure, but I'm wondering how old reliable that coil stamped "Renix" could be. Maybe same age as the truck and likely to fail at any time. Or it could last another 40 years, maybe? At any rate I need to figure out that "trigger a crank from under the hood" push button arrangement so I can put the multimeter on various things while it cranks. Mostly so I can check the CPS voltage. The CPS would would have been moved to the new bellhousing during the recent transmission swap, and maybe the move upset it. It's odd to me that CPS's fail. I thought it just held a magnet that generates the current sent to the ECU when the teeth on the flywheel pass by, and didn't contain any moving parts. How do they fail? Has nobody figured out how to restore them, or modify them to avoid whatever failure case makes the cheap units to go out so frequently? Link to comment Share on other sites More sharing options...
ghetdjc320 Posted July 17 Share Posted July 17 A couple of quick shots from the parts riffle might be better . The engine basically needs fuel and spark. If yours starts intermittently, then you’re likely getting some but not enough of one or the other. Both that coil and the fuel pump need consistent reliable electricity. So first check your battery. I suspect some people have an already low battery but because they clean up connectors or grounds, they manage to eek out a bit more current. Still doesn’t change the underlying battery as a possibility. As a battery’s voltage decreases, the current requirements of each component can increase. That’s when your wiring starts to really get tested. Test the voltage at the terminals while cranking. And once you get it running, test the voltage across the terminals while running. Next suspect would be coil or pump. Grab a coil and just return it if not needed or used. Fuel pump is a bit more involved but also entirely possible. You can chase your tail on all sorts of sensor readings that can all be simply due to a low/bad battery. Also worth checking the state of the plugs and wires, cap and rotor. CPS would also be in my list though maybe a bit further down. Link to comment Share on other sites More sharing options...
pizzaman09 Posted July 19 Share Posted July 19 I wouldn't throw out that coil, I tend to remember reading that they are excellent quality. My 90 Comanche still has the original French coil with 266k miles on it. Link to comment Share on other sites More sharing options...
Gojira94 Posted July 19 Share Posted July 19 17 hours ago, pizzaman09 said: My 90 Comanche still has the original French coil with 266k miles on it If you were to measure it per the post below, where does it ohm for primary and secondary? I'm loathe to replace mine if they still work a bit above resistance specs. Otherwise I'm taking a meter to the parts store to find one in spec. Link to comment Share on other sites More sharing options...
pizzaman09 Posted July 20 Share Posted July 20 19 hours ago, Gojira94 said: If you were to measure it per the post below, where does it ohm for primary and secondary? I'm loathe to replace mine if they still work a bit above resistance specs. Otherwise I'm taking a meter to the parts store to find one in spec. Measurements between all posts. I suspect this to be the original coil at 266k miles. Works perfectly. Link to comment Share on other sites More sharing options...
brucecooner Posted July 21 Author Share Posted July 21 On 7/17/2024 at 3:47 PM, ghetdjc320 said: A couple of quick shots from the parts riffle might be better . The engine basically needs fuel and spark. If yours starts intermittently, then you’re likely getting some but not enough of one or the other. Both that coil and the fuel pump need consistent reliable electricity. So first check your battery. I suspect some people have an already low battery but because they clean up connectors or grounds, they manage to eek out a bit more current. Still doesn’t change the underlying battery as a possibility. As a battery’s voltage decreases, the current requirements of each component can increase. That’s when your wiring starts to really get tested. Test the voltage at the terminals while cranking. And once you get it running, test the voltage across the terminals while running. Next suspect would be coil or pump. Grab a coil and just return it if not needed or used. Fuel pump is a bit more involved but also entirely possible. You can chase your tail on all sorts of sensor readings that can all be simply due to a low/bad battery. Also worth checking the state of the plugs and wires, cap and rotor. CPS would also be in my list though maybe a bit further down. I'm pretty suspicious of the battery at this point. The coil checks out (see below). I'm still running the battery that was put on there when I bought it a couple of years ago. The date on it is 01/22, and 2.5 years in the Arizona heat has probably not been kind to it. Add in also that the Jeep sat around for a while back when I was sick and working my way through the eternal brake job, so the battery was probably draining off a good amount. On 7/19/2024 at 12:41 PM, Gojira94 said: If you were to measure it per the post below, where does it ohm for primary and secondary? I'm loathe to replace mine if they still work a bit above resistance specs. Otherwise I'm taking a meter to the parts store to find one in spec. On 7/20/2024 at 8:26 AM, pizzaman09 said: Measurements between all posts. I suspect this to be the original coil at 266k miles. Works perfectly. THANK YOU for the helpful pictures, that made testing a breeze (coincidentally, I have the same multimeter). All my readings are about the same as yours. The two small round posts show 0.6 across, but I can wiggle the probes and get 0.7. Mine does show what looks like rust inside the galvanized(?) outer casing, and the water sealant near the top front has a couple of mild breakaways... But if the interior is wires encased in a big blob of plastic, I probably don't have to worry as much about the exposure. (I have cleaned the posts, that gray stuff is Oxgard) If these coils are known to last that long, I'll be keeping this one. I seriously doubt any new one is as well built as the original (even it it was made in France). In other news, I hooked the jump box to the battery a few days ago. It didn't start on the first crank, but it did on the second. And evening before last I test fired it and it started right up. So I'm less suspicious of the coil and more of the battery at this point. It's a Duralast Gold. I used to run Duralasts in my Ranger, but I never got much beyond 3 years with one. This one has been sitting in the Arizona heat for going on three years, and sat without being recharged for stretches of time while me and/or the Jeep was down for repairs. The battery posts show 13+ at key off and 14+ at idle, which seems normal but I don't think I can tell how much cranking oomph it has just based on that. I wouldn't trust the Autozone test either. A few months ago they told us the battery in our Honda was good, but the key off draw was within spec so we changed the battery anyway and that was indeed the problem. Can anyone recommend a battery that might stand up to the heat a little better? Are the AGM's better for a hot climate? Are the Optima's worth the premium? Or are they all a crap shoot these days? One other question, is that flat spade connector between the small posts supposed to connect to something? Mine reads the same as the pictures, but I can't tell that there is anything in the coil cradle for it to connect to. Link to comment Share on other sites More sharing options...
Ωhm Posted July 22 Share Posted July 22 2 hours ago, brucecooner said: One other question, is that flat spade connector between the small posts supposed to connect to something? Early RENIX years (Volvo), spade connector was used for a Radio Suppression Capacitor. ICM_EARLY RENIX VOLVO_2.pdf Link to comment Share on other sites More sharing options...
pizzaman09 Posted July 22 Share Posted July 22 2 hours ago, brucecooner said: THANK YOU for the helpful pictures, that made testing a breeze (coincidentally, I have the same multimeter). All my readings are about the same as yours. The two small round posts show 0.6 across, but I can wiggle the probes and get 0.7. Actually mine was reading 0.6 most of the time I took the reading but at the instant the photo was taken it measured 0.7. It sounds like your coil at least similar to mine and mine works great. Link to comment Share on other sites More sharing options...
eaglescout526 Posted July 22 Share Posted July 22 3 hours ago, brucecooner said: Can anyone recommend a battery that might stand up to the heat a little better? Mopar. Haven’t had an issue with either one. That I have/had. The first one I think lasted me about 4 years before it gave up and the second one I’ve had for maybe about 2 now. Maybe 3. Link to comment Share on other sites More sharing options...
brucecooner Posted July 23 Author Share Posted July 23 It looks like the stock battery group size is 58, but lots of guys prefer running a group 34. It is also apparently a bolt-in fit in earlier XJ/MJ's? The size charts I've seen indicate the 34 is about an inch taller though. I have the stock tray without any sort of spacer in the bottom that some have mentioned removing. I'd definitely spring for the 34 for the extra cranking amps, but I don't want to run the risk of shorting against the hood. Link to comment Share on other sites More sharing options...
fiatslug87 Posted July 23 Share Posted July 23 I use group 34 in all my MJs with the stock battery tray, no problems with clearing the hood. If you still have the stock bracket that bolts to the radiator support you’ll have to flip it. I’ve read that AGMs need a slightly higher charging rate ~14.5 volts for optimal lifespan, not sure if that’s a real problem. Link to comment Share on other sites More sharing options...
eaglescout526 Posted July 23 Share Posted July 23 51 minutes ago, brucecooner said: It is also apparently a bolt-in fit in earlier XJ/MJ's? Nope. Tried a G34 in my 84 XJ and it will not fit. The hold down is different for 84-86. Link to comment Share on other sites More sharing options...
brucecooner Posted August 12 Author Share Posted August 12 I did that trick of jamming cardboard tubes together, sitting them upright in the battery tray at the point where the posts would sit, closing the hood, and getting the clearance from the final length of the tubes. This gave me fairly precise clearances at the posts. Negative looks to be about 8 and a quarter inches. With the positive side about 10 and 3/4ths inches. I can't remember the height of a group 34, but I think it was like 7 and 7/8ths. So not quite an inch on the negative side, but plenty on the positive side, which is probably where it really counts. So I got the group 34 and as all the old timers around here have said, it sat in a stock '88 tray without needing any mods. The stock hold down system wasn't very pleased with my decision, the nuts on the threaded uprights aren't going on very far, and I think I backed them off out of fear the bar might warp the battery. And don't worry, I moved the loom around that coolant hose further down so it's fully between the hose and battery. I plan to get a boot to go over the positive terminal too. This hold down is sturdy, but I have to wonder if there's any options for this system. The uprights tend to fall down, and I'd prefer something that's a better fit to the battery. Our Mustang has a sturdy fabric strap that goes across the battery that is the easiest system I've ever used. Loosen one tall 10mm bolt that sticks up on one side and lift the strap. Easy to put back and nothing drops down into the dark voids of the engine bay. Anyway, the $65,000 question, the whole point of this thread, did this fix my problem? YES! It's started every time I've turned the key since dropping this one in. As can be expected, about a week after I replaced this battery, the one in the Mustang gave out, so it was good I got this guy back on the road when I did. So a big round THANK YOU to everybody who helped out here. Link to comment Share on other sites More sharing options...
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