Difficulty starting

Woogybugger

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Hi all, hope this has not already been discussed. I don't know how to search the forum yet.

-1997 TJ pretty stock under the hood. Owned it for a year now an it has started consistantly on the third try(problem one but of less concer) a couple months ago the PS pump blew up and there was fluid everywhere under the hood. So, I sprayed it off at the carwash. Since then the jeep only intermittently starts. Maybe 20 % and usually when I first try in the morning. If I remove the air intake tube and give it a shot of ether it starts and runs fine.

I stumped, so far the only adrive I have been given is to replace the spark plugs which makes no sense to me.

Ideas would be appreciated. If this has already been discussed a link to the thread would be helpfull. I am using a Mobil version and can't find the search tools.
 
@Woogybugger

Okay, to me it sounds like the issue with always starting on the third try was the original problem but now it's just gotten worse.

So, what it sounds like is that it turns over and will occasionally start 20% of the time. That tells you that you have power so you can rule that out. I highly doubt it's the spark plugs, but if you want to rule out something and take care of some cheap maintenance in the process I would do the spark plugs, distributor cap, and rotor.

Before I think about this more I have to ask, once it's started and running (on the few times it will start) does it run well and drive fine without any hesitation?
 
@Woogybugger

Okay, to me it sounds like the issue with always starting on the third try was the original problem but now it's just gotten worse.

So, what it sounds like is that it turns over and will occasionally start 20% of the time. That tells you that you have power so you can rule that out. I highly doubt it's the spark plugs, but if you want to rule out something and take care of some cheap maintenance in the process I would do the spark plugs, distributor cap, and rotor.

Before I think about this more I have to ask, once it's started and running (on the few times it will start) does it run well and drive fine without any hesitation?
 
Yes runs fine. Either way when it starts (still on third try) it runs great. When I use starting fluid it also runs well. No hesitation, typical power, everything is good.
 
Yes runs fine. Either way when it starts (still on third try) it runs great. When I use starting fluid it also runs well. No hesitation, typical power, everything is good.

Okay, well in my mind the fact that it will start on occasion (and then runs fine when it does start) pretty much rules out a fuel problem. Normally if the fuel pump were bad (or an injector) it would run poorly when it did start.

To me this seems like something related to the ignition / electronics. I assume there is no check engine light at all? You'd think there would be, and if there is that will pretty much answer your question for sure. So, first make sure there is no check engine light (hopefully there is one).

You could replace the cheap things like start plugs, distributor cap and rotor just for maintenance and to rule them out. However, there's a chance it could be something like the CPS (Crank Position Sensor) or another sensor going bad.

The Crankshaft Position Sensor (CPS) located on the transmission bell housing. Often this part is also referred to as the Crankshaft Position Sensor (CKP) CPS/CKP failure is very common. The CPS/CKP can stop working with no warning or symptoms and the engine will not run or the engine may randomly stall for no apparent reason.

Typical Symptoms –

- Starter cranks and cranks but engine won't start up and run.
- Fuel gauge and voltage gauge may not work or display properly.
- Engine may randomly stall for no apparent reason.
- You sometimes will have No Bus on the odometer after 30-60 seconds.
- A failed CPS/CKP may or may not throw a CEL trouble code.
- No spark at the spark plugs.
- Fuel pump should run and prime for 3-5 seconds.

Begin with basic trouble shooting 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. Do the same for the grounding wires from the starter to engine block, and from the battery and engine to the Jeep's frame/body. You must remove, scrape, and clean until shiny, the cable/wire ends, and whatever they bolt to. Jeeps do not tolerate low voltage, bad connections, or poor grounds and the ECM/ECU may behave oddly until you remedy this.

Exchange the fuel pump relay and the ASD relay with one of the other similar ones in the PDC to eliminate the relays as the cause of the no-start. Check the ASD relay fuse.

Confirm that the fuel pump to runs for 3-5 seconds when you turn the ignition key to ON.

Eliminate the NSS as a cause of no start. Wiggle the shift lever at the same time you try to start. Put the transmission in Neutral and do the same. Do the reverse lights come on when the shifter is in Reverse?

Inspect the wires and wire connectors at the O2 sensors on the exhausts pipe. A short circuit from melted insulation or from broken O2 sensor wires can blow a fuse and the ECU/ECM will loose communication. Don’t get tunnel vision and assume the sensor is bad (unless it tests bad with a meter). Damaged wiring or a dirty connector can inhibit the signal from making it to the computer. Inspect/test/clean/repair wiring or connectors as necessary.

If the CPS/CKP is failed sometimes the OBD-II trouble code reader cannot make a connection to the ECU/computer or cannot read Check Engine Light/MIL codes because the CPS/CKP has failed. Disconnect the code reader, disconnect the CPS/CKP wire connector, and reconnect the code reader. If the code reader establishes contact with the ECU and scans, your CPS/CKP is failed and needs to be replaced.

Crank Position Sensors can have intermittent “thermal failure”. This means that the CPS/CKP fails when the engine gets hot, but works again (and will test as “good”) when it cools back down.


Diagnostic steps to confirm the CPS is the cause of your no-start
1) You should be able to verify a bad cps, by unplugging it, and turning the ignition key to on. If the voltage gauge and/or the fuel gauge now display correctly and/or the No-Bus is gone, replace the CPS.

2) If the CEL does not come on when the key is turned to the RUN position... then the CPS/CKP is bad.

3) Unplugging and reconnecting the CPS sensor where it connect to the main harness near the back of the intake manifold usually resets the ECU and if the jeep fires right up after doing this you can bet that the CPS is faulty and needs to be replaced.

CPS Testing

Crankshaft Position Sensor Connector (CPS/CKP)


standard.jpg

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standard.jpg



TESTING PROCEDURE 1991 – 2001 4.0L H.O. engines
1. Near the rear of intake manifold, disconnect sensor pigtail harness connector from main wiring harness.
2. Place an ohmmeter across terminals B and C (See Image). Ohmmeter should be set to 1K-to-1OK scale for this test.
3. The meter reading should be open (infinite resistance). Replace sensor if a low resistance is indicated.

TESTING PROCECURE for 1987 – 1990 4.0 L engines
Test # 1 - Get a volt/ohm meter and set it to read 0 - 500 ohms. Unplug the CPS and measure across the CPS connector's A & B leads. Your meter should show a CPS resistance of between 125 – 275 Ohms. . If the CPS is out of that range by much, replace it.

Test # 2 - You'll need a helper for this one. Set the volt/ohm meter to read 0 - 5 AC volts or the closest AC Volts scale your meter has to this range. Measure across the CPS leads for voltage generated as your helper cranks the engine. (The engine can't fire up without the CPS connected but watch for moving parts just the same!) The meter should show .5 - .8 VAC when cranking. (That's between 1/2 and 1 volt AC.) If it's below .5vac, replace it.


The 2000 and 2001 will have the CPS in the same location on the bell housing, but the wire connector is near the Transfer Case, not as shown in the diagram below. Simply follow the wire from the sensor to the connector.

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standard.jpg


Anyways, might be worth ruling the CPS out as well, but let us know if there is a check engine light!
 
Sounds like your dealing with 2 issues now, as for the original issue starting on third try I'd say fuel pressure issue.
Now for the 2nd issue with only starting 20% It is possible you got water where its not supposed to be high pressure soapy water and electrical connectors don't mix all. It only takes one drop of water to conduct inside of a connector. Start looking at all of the connections under the hood blow em out with compressed air and put some dielectric grease in each one and you should be fine.

-Jason
 
Never aggressively wash under the hood of a car with water. I learned that mistake when I was much younger. If any of that water gets in the electrical connections (which it likely has in your case), well it doesn't mix as I'm sure you're now aware.
 
I doused my entire engine bay with simple green sprayed it with high pressure water several times in one day to clean out my engine and bay. I covered up a few of the electrical components in there but I didn't try to start it up until I knew it was all dried out.

Didn't have any problems and now it's super clean in there!
 
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I doused my entire engine bay with simple green sprayed it with high pressure water several times in one day to clean out my engine and bay. I covered up a few of the electrical components in there but I didn't try to start it up until I knew it was all dried out.

Didn't have any problems and now it's super clean in there!

Yeah, if you wait until it's all dried out that's usually fine. I've done the same thing myself!