ttanton

I’m going to check all of these shortly and follow up. Thank you all

Correct, the O2 sensor reading does not bounce at all, it falls to 0.3 ish and stays there. I’ve replaced the o2 sensor this week with an NTK and there is no change in readings.

Hey Guys & Gals, I've got a problem with getting the fuel mixture running too rich - ECU can't settle into closed loop and fuel economy is pretty poor. It idles and runs pretty solid, but the vapors can be overbearing, and I would appreciate an improvement at the gas pump. I've done a lot of digging around the forum and elsewhere, but could use some advice on next steps for troubleshooting and determining my issue. I have a REM monitor. Here's what I know: ECU stays in open loop ~95% of the time REM Monitor Code: Loop Fault Rich Fuel Economy ~11mpg (stock 4.0, stock tire size, 2wd, city) Oxygen sensor pegged to ~0.3 idle & throttle, 4.92 in decel/DFCO MAP ~13 inHg @ idle CTS always maxes out between 150 - 180F (thermostat replaced with mopar recently) IAC walks down to 0 and limits out. New fuel pump ~ 6 months ago by a shop. Idles fine Grounds have all been refreshed following cruisers tips. Oxygen sensor back probes and tests as accurate/operational as best I can tell. When starting the vehicle, the reading starts around 4.9 then falls to 0.3 over the first 5 seconds or so, then is stuck around there unless in DECEL mode when the reading jumps to ~4.95 ish until ECU enters back into open loop. As far as I can tell, the REM is correctly portraying an overly rich exhaust. So breaking this down out loud.... the engine is either getting too much fuel, or not enough oxygen. Since it seems to run strong, my guess is it's getting enough air - also I would think that MAP would be lower than 13 at idle if it wasn't getting enough air. I'm not real familiar with the injectors. The PO replaced them a couple years ago, but I'm not sure how to tell if sizing or other factors could be the cause. I also don't have a fuel pressure test kit, but I could also suspect that the fuel pressure at the rail is too high as a possible cause. Any advice on next steps for troubleshooting or identifying where the issue lies? A lot of the reading I've done around here concerns the mixture being too lean, but not much to go on for investigating an overly rich mixture. Thanks in advance!

Thank you all for the quick replies and suggestions. Hope everyone has a great new year! Cheers.

Got it turn over! Spark again at the plugs. dang SOB. My guess is, the in high voltage terminal on the distributor cap didn’t have a good connection. It had some corrosion on it. Me plugging and unplugging and wiggling was enough to reconnect everything. That or the terminals from the wiring harness to the ignition coils. Those were pretty rough too, I brushed and bent them back for better contact with the coil block.

I put a plug in the wire from the ignition coil and cranked and did spark from there. Going to look at what ohm shared above too though

I am getting infinite resistance between positive terminal and high voltage terminal or case. So secondary resistance seems okay

Testing the ignition coil. I’m only getting about 0.5 ohm resistance between positive and negative terminals. Chitons says I should be .95 - 1.2. Not sure if that’s far enough off to be a problem though. It’s a spectra ignition coil, looks relatively new, replaced by PO.

Confirmed no spark at the plugs. trying to work my way backwards and up the line to see what’s failed I guess.

Headed over right now. Will be checking all vacuum tubing from the intake manifold to map & fuel pressure reg, and check on the cps wiring and sensor tip if I can get to it. Thanks all - will follow up once I know more this morning

@Alan C No, it doesn't fire at all - dead as a doornail. Thanks for the reply.

I’m going to try both of these tomorrow morning when I head over there - I’ll check the cps connector and vacuum hose to the FPR. Thank you both

Hey guys, Heavy lurker here. I'm a relatively new owner (about 1 year). Been working through Cruisers mostly renix updates, driving the truck 2 - 3 times a week. It's been mostly solid for me minus a fuel pump replacement about 6 months ago. The problem: Today while running errands, I was on my 3rd or 4th stop when the truck just straight up wouldn't start. I have never had trouble starting the truck throughout the last 12 months. But today after starting several times just fine along the way, it wasn't even thinking about it. Strong crank, smells relatively rich after cranking a while, but seems like no fire. The electrical in this rig is not the best, whacky stuff from PO etc, but again, it has generally been trustworthy and I've refreshed most of the grounds etc. It's (not) driving me nuts how it just went from 100% fine to 0% fine so quickly It's currently stranded at the local gas station. I'm going to head back tomorrow morning to play with it for a few hours before resorting to towing measures. My plan so far is the following: Check for spark Check for fuel pump power/fuel pressure (pump replaced ~ 6months ago, priming has been silent since then, so hard to hear, but when cranking and no start, exhaust smells rich) Check CPS I'm all ears if anyone has ideas for relatively simple gas station diagnostics. I installed NickInTimes REM too if that can help. Not much else to note. Blower motor fuse blew a few days ago, and I played around a little in the fuse box below the driver to address that (all sorts of jumps and whacky stuff down there, but again nothing changed recently since it's been running well). Thanks in advance for any advice. I'll be browsing through existing topics heavily as well in case I can draw anything there. Cheers.

Just as note to myself, I removed the TPS & IAC (both which look relatively new and clean, and re-installed, and it idles great now. The TPS was very loose as the screws were not tight. Between that, and wiggling some wires, and reseating the IAC, something changed. Runs like a champ again now!

Hi folks, Just wanted to introduce myself as the happy new owner of this comanche. I'm in south Austin and have been looking for an older truck to help with home and landscape projects around the house (been sharing the wifes SUV until now). I had great luck in finding this truck and it fitting my interests. The fact that it's such a peculiar model is the icing on top. I'm not looking to do any extensive reno to it, but do want to take care of it and plan to put her to good use for the next 10 years of her story. It has good bones. Bed is in great shape. Floor board has some reasonable rust under the heels of the driver, other wise appears to be fairly good shape. It has vinyl floor in it, thinking I may need to check under neath after our next good rain. Door window wipes/weather strip needs to be replaced asap. Any rain on the door windows is going right into the door body right now. It's run strong, but today I noticed the idle was particularly high when I started it, and after a trip around the block, it only began to creep higher. No idea on that, believe I will check the TPS & IAC when I get a moment and hope thats the issue. Hasn't been that way anytime previously in the 20 miles that I've owned it. Also I hate not having a tach to reference RPM, having to rely on sound. Speedo doesn't work. Have a new cable to replace. Cheers.