2000 having some starting issues

Being in need of a winter-capable car for a college internship and having a few friends with XJ's, picking one up was an easy choice. I got a no-rust 2000 sport (coil-on-plug, 3 cat CA compliant) for $750 (~215k mi.) in need of what seemed like some minor to moderate work. Through my univ., I have access to a full machine shop (stick, mig, tig (mild, ss, alum, ti), manual mills and lathes, CNC mill and lathe, etc. free to use whenever) and automotive shop worth of tools (Formula SAE club), so "some wrenching required" didn't shy me away from this jeep.

I've dropped in a new battery, sealed beams, air filter, thermostat, oil and filter, and plugs. I also put in a known-to-work set of coils, starter motor, o2 sensor, and injectors (from a friend who did the 784 neon swap). I also replaced the rear hatch with one that had glass in it since plexi wouldn't have passed PA inspection.

When I bought it, there were some over heating issues, so I bypassed the heater core thinking it'd be clogged and that'd get me home. With no luck, I found it to be a seized thermostat, so I just pulled it and drove home. It idled and still does idle rough. It had a cyl. 2 misfire CEL (via BT OBD2 reader) which turned out to be a plug with a gap less than .010". I replaced all 6 and found the basically closed one in cyl 2. That CEL went away, but then I got one on bank 1 sensor 1 o2 sensor. I dropped in a working one, but have had issues getting it to start despite the work done.

EDIT: I should also note that the alternator puts out a constant 14.x volts when the thing is running.

Now, it's got the above list of swapped parts, a reattached heater core, some fresh gas, and just doesn't want to start, it'll crank hard and stumble a bit, sound like it's about to kick over sometimes, but I don't want to drain this new battery just cranking and cranking and cranking. My last thought is that it could be a bad CPS, but I drove it home, so if it was bad, there'd be no spark at all.

Anyways, if you've read this far, thank you in advance for any help you might have to offer up!

If it cranks the starter but will not run, suspect the CPS. If it cranks the starter and struggles to run, suspect the battery, alternator, or starter, corrosion within their wires, or loose/poor quality wire connections. If it will not engage the starter, suspect the Neutral Safety Switch.

Tim_MN said:

If it cranks the starter but will not run, suspect the CPS. If it cranks the starter and struggles to run, suspect the battery, alternator, or starter, corrosion within their wires, or loose/poor quality wire connections. If it will not engage the starter, suspect the Neutral Safety Switch.

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Thanks! I think I'm going to hit it with some ether or double prime it to rule out low fuel pressure, then start looking into the CPS. I know it's a bear to change so if it's just not priming strong enough, I'd rather drop the tank and do that than grow a few more elbows to reach the CPS.

In the past few days, it's struggled to start, taking half a dozen solid crankings or so, but it would eventually fire up. Sometimes I'd hook up the jumpers to avoid sucking the battery dry. Battery is new and alternator runs at 14.x volts when running. Wires would be worth checking as well... I really doubt it's the NSS since it'll always fire the starter.

Test the fuel pressure, it should be 49 psi +/- 5 psi. A faulty fuel pressure check valve may cause a no-start on the first try, but will almost always start on the second try. If you need more than two tries to start I would suspect low voltage. Test the CPS is easy and should rule it in or out as weak/faulty.

Perform routine maintenance of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Copper wires should be copper color, not black or green. Do the same for the grounding wires from the starter to engine block, the ground wires at the coil, and the ground wires from the battery and engine to the Jeep's frame/body. You must remove, wire brush, and clean until shiny the cable/wire ends and whatever they bolt to.

Jeeps do not tolerate low voltage, bad wire connections, or poor grounds.

Place your DVOM (Digital Volt Ohm Multi-Meter) on the 20 volt scale. First check battery voltage by placing your multi-meter's positive lead on the battery's positive post ( the actual post, not the clamp ) and the negative lead on the negative post. You need a minimum of 12 volts to continue testing. Next, leave your meter connected and take a reading while the engine is cranking. Record this voltage reading. Now connect your positive lead to the battery terminal stud on the starter and the negative lead to the starter housing. Again, crank the engine and record the voltage reading. If the voltage reading at the starter is not within 1 volt of battery voltage then you have excessive voltage drop in the starter circuit.

Typical voltage drop maximums:
• starter circuit (including starter solenoid) = 0.60 volt
• battery post to battery terminal end = zero volts
• battery main cable (measured end to end) 0.20 volt
• starter solenoid = 0.20 volt
• battery negative post to alternator metal frame = 0.20 volt
• negative main cable to engine block = 0.20 volt
• negative battery post to starter metal frame = 0.30
• battery positive post to alternator b+stud = 0.5 volt with maximum charging load applied (all accessories turned on)

Test the output at the alternator with your volts/ohms multi-meter. You should be measuring 13.8-14.4 volts. Load testing the alternator is still recommended.

Have your helper turn the ignition key to START while you tap on the starter with a hammer. If the engine starts, you probably need a new starter.

Have the battery, starter, and the alternator Load Tested for proper function in a test machine that applies a simulated work load. Handheld testers are inaccurate and will often pass faulty parts.

nmac985 said:

I know it's a bear to change so if it's just not priming strong enough

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It's actually not that bad after the first time...you will need a very long extension. Basically, you will lay underneath the XJ with your head facing the rear wheels. With a long extension, you will be able to reach the bolts and see what you are doing. First one takes you 45+ minutes...10 minutes max for every one after that.

Tim, thanks for a detailed response. I didn't get to put a fuel pressure gauge on the rail, though after priming it a few times, it still wouldn't kick over. Additionally, about an hour or two after, when I poked the rail pressure release, a jet of fuel shot out, so I don't think the fuel pump is what's causing the starting issues.

As for the electricals, I pulled the battery, block, and starter grounds and cleaned up their connections. Both the battery and block were grounded to painted surfaces. Which ground wires are you talking about for the ones on the coil?

I got out my little multimeter and poked around a bit, as well. Terminal to terminal was 12.4x volts consistently. This is a brand new battery (Diehard ~800 CCA from this past weekend), so I expected it to pass the 12V minimum test. I also have a charger I can put it on while I'm working a bit later just to top it off. I didn't have anyone with me, so I couldn't do a lot of the tests you mentioned, but I'm going to give it a whack tonight, maybe.

FWIW, the alternator did read fine on the dash when I drove this thing the other day. Is the hammer test for the starter solenoid? Finally, getting these parts load tested is kinda tough being that the thing currently doesn't drive. I think I'm going to pick up a new CPS today, check the above listed electrical connections, and then see what happens. I'm about to throw in the towel and hand it off to a shop because snow is looming and my other straight 6'd car isn't going to like that.

So, I typed up a nice breakdown of all of the voltages I pulled from the engine bay as I did them. Then my phone rebooted and I lost it all. Moral of the story... Battery + to:

Other terminal, negative terminal chassis ground, engine braided ground, starter ground, alternator stamped steel housing, valve cover (with paint scratched off), etc. all read 12.75 +- .02V.

The only odd thing I found was battery + to coil connector. With the coil pack out, the connector from left to right with the bump upwards read out: 11.48, 11.48, 12.74, 11.48V (I might have transposed pins 2 and 3, it was correctly stated in my lost response).

I was working solo tonight so I couldn't get any readings while cranking.