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Old 04-10-2010, 04:10 PM   #1
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Jeep Cranking, Wont start, Testing the CPS?

I have a 99' Wrangler 5 speed, 4.0

It will crank but not start.

To this point I have:
1.Replaced distributor cap
2.Replaced ignition rotor
3.Charged battery and cleaned terminals
4.Checked ignition coil and it tested out
5.Replaced spark plugs and wires - have spark
6.Removed the Crank Position Sensor

I read on other threads on here that the next logical problem area after steps 1-5 would be the crank position sensor.

Seeing that, last night I unbolted it from the transmission bell housing (bit of a knuckle busting exercise). The only way to test I have is a multi-meter. Is there a method to do this? I do get a reading of .67 ohms resistance and when i turn the ignition to start i can here the distributor "react" when i plug and unplug the CPS from the transmission housing, which leads me to believe it's okay. I went to NAPA and it's $110 for a new CPS so I don't want to replace it if it's okay.

That being said, if it's not the CPS what is the next thing to check/do? I'm on my last step before getting it towed and having a real mechanic fix it.

I don't want to raise the white flag just yet, need some help

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Old 04-10-2010, 04:29 PM   #2
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There are so many different options that can cause you to have a no start. And it is tough to tell over the internet which one it is. But the CPS is where I would look last. Are you sure you are getting fuel to the rail? Does it smell like gas after cranking for awhile and no go?

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Old 04-10-2010, 09:52 PM   #3
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There are so many different options that can cause you to have a no start. And it is tough to tell over the internet which one it is. But the CPS is where I would look last. Are you sure you are getting fuel to the rail? Does it smell like gas after cranking for awhile and no go?
I took the air intake off the throttle body and smell gas in the throttle body, don't know how to tell if it's making it to the fuel injector rail. It smells like gas after cranking and no go.
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Old 04-10-2010, 10:07 PM   #4
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The only thing you don't mention is the starter... I would have made that number 2 after messing with the battery and before all the other options.

2yrs ago I had an issue where it would not start but had power to everything. With the help of another person and a piece of wire I jumped the starter and turned out the factory plug wasn't making conntact anymore. I cut the plug off and replaced with another and have not had issues since
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Old 04-10-2010, 10:21 PM   #5
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The only thing you don't mention is the starter... I would have made that number 2 after messing with the battery and before all the other options.

2yrs ago I had an issue where it would not start but had power to everything. With the help of another person and a piece of wire I jumped the starter and turned out the factory plug wasn't making conntact anymore. I cut the plug off and replaced with another and have not had issues since
Here you go dude.


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It will crank but not start.
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Old 04-10-2010, 10:24 PM   #6
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I'm not sure on how to test the CPS...but $110 seems waaaay high. I paid under $50 for one when I replaced the one in my old truck. Might wanna shop around and see if other places are all that high.

Btw...welcome to WF. Just noticed you're not too far away!
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Old 04-11-2010, 09:35 AM   #7
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Alright, gonna try and hot wire the starter. I didn't think that it would crank if the starter wasn't working.
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Old 04-11-2010, 09:38 AM   #8
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Alright, gonna try and hot wire the starter. I didn't think that it would crank if the starter wasn't working.
It won't.
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Old 04-11-2010, 11:13 AM   #9
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It won't.
So it's not the starter then, cus its cranking like normal
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Old 04-11-2010, 11:15 AM   #10
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I'm not sure on how to test the CPS...but $110 seems waaaay high. I paid under $50 for one when I replaced the one in my old truck. Might wanna shop around and see if other places are all that high.

Btw...welcome to WF. Just noticed you're not too far away!
Thanks man, my gf teaches up in Piqua

I'll look around, but the guy said the automatic trasmission one was $50 and the manual was $100, so that may have something to do with it.
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Old 04-11-2010, 11:19 AM   #11
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So it's not the starter then, cus its cranking like normal
Correct.
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Old 04-11-2010, 11:19 AM   #12
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it sounds like you spent to much already.a mechanic would have fixed it by now.
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Old 04-11-2010, 11:21 AM   #13
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Great, sounds like I'm getting a tow
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Old 04-11-2010, 11:26 AM   #14
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Why keep randomly throwing parts at it?
Why not troubleshoot the problem?

If the CPS was bad, you would have no spark and no fuel. So obviously yours is OK.

Start in a logical way.

Does it crank at what seems like normal speed?
Does it have a good thin blue spark at the plugs?
Does it have fuel in the fuel rail - momentarily press the tire type valve on the fuel rail.
When you crank it - put your fingers on an injector, you should feel it clicking.
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Old 04-11-2010, 05:22 PM   #15
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Why keep randomly throwing parts at it?
Why not troubleshoot the problem?

If the CPS was bad, you would have no spark and no fuel. So obviously yours is OK.

Start in a logical way.

Does it crank at what seems like normal speed?
Does it have a good thin blue spark at the plugs?
Does it have fuel in the fuel rail - momentarily press the tire type valve on the fuel rail.
When you crank it - put your fingers on an injector, you should feel it clicking.
It cranks strong, sounds like it should start and just doesn't turn over
Good spark
Has fuel in the rail
Injectors clicked
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Old 04-11-2010, 05:50 PM   #16
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I take that back, I'm not feeling anything "clicking" at the injectors
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Old 04-11-2010, 06:53 PM   #17
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Good - now we are getting somewhere.

Go to the relay box, find the ASD relay - automatic shutdown relay. Swap it with another relay - like the horn relay.
Try to start it now.
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Old 04-11-2010, 07:45 PM   #18
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Good - now we are getting somewhere.

Go to the relay box, find the ASD relay - automatic shutdown relay. Swap it with another relay - like the horn relay.
Try to start it now.
Swapped it out and no luck
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Old 04-11-2010, 08:12 PM   #19
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I assume you've checked ALL the fuses?

Remove either battery cable.
Notice the relay box comes apart, the top splits from the bottom. Carefully take it apart - look for corrosion or loose connections. Repair as needed.
Use a good contact cleaner to clean it.
Reassemble, remove each relay in turn and spray down the sockets.

Since you have spark and fuel pressure, but the injectors are not triggering, most likely its an electrical connection problem.
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Old 04-11-2010, 08:21 PM   #20
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I assume you've checked ALL the fuses?

Remove either battery cable.
Notice the relay box comes apart, the top splits from the bottom. Carefully take it apart - look for corrosion or loose connections. Repair as needed.
Use a good contact cleaner to clean it.
Reassemble, remove each relay in turn and spray down the sockets.

Since you have spark and fuel pressure, but the injectors are not triggering, most likely its an electrical connection problem.
Thanks rrich, I'll try this out tomorrow and glad I might be narrowing this down.
Of course its dead in the driveway on the best cruisin' weather we've had all year
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Old 04-12-2010, 07:39 PM   #21
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Okay - opened up the relay box, wiped everything down including the battery leads that hook into what looks like a bolt on an electric bus bar on the firewall side of the relay box. Didn't see any rust or corrosion but cleaned it up anyway. Hooked it all back up and...still not turning over.

I don't know what you meant by spraying down the sockets
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Old 04-12-2010, 08:25 PM   #22
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The bottom of the relays have blades that plug into sockets. Make sure they are clean and have good contact.
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Old 04-16-2010, 01:00 PM   #23
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Angry

I've cleaned everything

I got a fuse tester and the tested every fuse in the relay box and in the fuse panel behind the glove box just to be double sure

I took a circuit tester (The light with a power lead attached) and tested to make sure there's a circuit from the battery to the ASD relay and from the battery to the injectors

Everything is testing out fine fuse and relay wise

Still not turning over
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Old 04-18-2010, 10:33 PM   #24
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My Jeep had the same problem just recently. I was driving suddenly the tachometer went to zero and I coasted to the side of the road. I would try to start it and it would crank but the engine would not start. After having it towed home, I went through the same checklist that everyone else here is telling you to do. Eventually, it dawned on me that fuel was not getting to the rails. It was the fuel pump. They usually go out after 80K-90K miles or so. I have 172K on mine and this was the second one that had to be replaced (First one was around 90K). What is the mileage on your TJ?

If it is your fuel pump, it should not be that bad of a repair. It cost me around $500 at a trusted repair shop. This is a messy repair, so I strongly recommend that you do not attempt this yourself. You do not want to be banging metal around those fumes.
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Old 04-19-2010, 01:25 AM   #25
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Well, you've said you have fuel in the rail, and smelled fuel in the Throttle body. But - you may not have enough pressure.
Try something - get some starting fluid from the parts house. Spray about 1/2 teaspoon down the Throttle body throat. Try to start it. The starting fluid will duplicate fuel and it will try to start for a moment if it really is a lack of fuel. KEEP YOUR FACE BACK - IT MAY BACKFIRE!

If it starts it's one of 2 things - either there's not near enough fuel pressure in the rail - pump, or the injectors are not firing.

Fuel pressure - Maybe you can beg, borrow, or steal a fuel pressure gauge? Some parts houses will rent them. If the pressure is too low, from a bad pump, it won't run. You can buy a new pressure gauge from Harbor Freight for about $19,95, even lower on Ebay.

If fuel pressure is fine - I think it should be about 49 lbs, next step is see if the injector is triggering. Feel real closely again for the subtle clicks when cranking.
No? I'd suggest getting a Noid light from the parts house - I think it's about $5. It's a little light bulb that flashes if the injector is firing. Maybe you can even borrow one.

If it's not flashing, trace the injector harness back to the rear of the engine - I think there's a connector back there that I suppose could come loose.

Next step would be the ECM, but there's a few more things to try first.
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Old 06-14-2010, 10:53 AM   #26
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Alright - I know I have been off for a while, but I thought that I'd get back on and let everyone know the end result. The ignition coil (yes the one I bench tested and thought was working correctly) while it was giving spark, was not giving enough.

Replaced it and now it's all good.

Just goes to show, the simplest answer is usually the correct one.

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