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Old 12-07-2011, 01:15 AM   #1
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Unhappy TJ spins engine but No Start

I have an '05 4.0 6sp TJ. Drove it to work, all was well, eight hours later she would not start. It spins the engine fine (new battery) but will not hit. I sprayed ether into the manifold and she hit a few times, this tell me she's firing. I checked (in fact swapped the relays around) relays and fuses with a DVM, all check good. My next step is to check fuel pressure, but Chrysler did not provide me with a check port, so I have to come up with an adapter to do so. The fuel pump gives the normal 3-5 second humm on initial "key on". I did check the ASD at both the relay and PDC, all values checked out per service manual. There are No codes recorded on my code reader, OBD11. I do not want to just start replacing fuel pump and other parts in a blind frenzy. Can the check valves on the fuel tank cause such? Fuel pressure regulator/filter? I do not have access to the diagnostic computer of with the manual speaks so highly of, but with no codes, do I need it? I even tried swapping my spare key, no difference.(had a GM "security" ignition switch do this to me). I am open to suggestions. Thanks

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Old 12-07-2011, 01:23 AM   #2
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If the fuel pump pressures up that says to me it's a spark issue. Pull off a plug wire, have someone crank it and see if you have an arc to ground. Off the cuff, I'm going to say CPS.

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Old 12-07-2011, 03:02 AM   #3
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cps
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Old 12-07-2011, 04:28 AM   #4
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It might be your ecu. Computer might not be reading right. also check injectors n spark plugs...
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Old 12-07-2011, 06:22 AM   #5
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People complain about the engine cranking but not starting. When its cranking and not starting you also dont have a Check Engine Light during cranking and when they put the key in position 2. Then all of a sudden when your cranking and about ready to quit your Check Engine Light comes on and the jeep starts.

People spend a good amount of money trying to fix this problem on stuff that is not the problem. The problem lies with the vehicles engine computer also known as the PCM, ECM and ECU.
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Old 12-07-2011, 09:35 AM   #6
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I will check fuel pressure and if it's acceptable, CPS next. May be Sat before I can. Thanks for input guys.
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Old 12-07-2011, 01:28 PM   #7
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easiest thing to do is to see if you have spark, then fuel.
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Old 12-07-2011, 02:20 PM   #8
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It might be your ecu. Computer might not be reading right. also check injectors n spark plugs...

yup...ecu can quit anytime w/o warning.
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Old 12-08-2011, 07:25 AM   #9
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Not that easy, 05 has some kind of a coil pack rail. No plug wires, looks like boots are an integral part of rail. Remove one, remove all.
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Old 12-08-2011, 07:33 AM   #10
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Been through this before. I would definitly replace the crank sensor. Cheap enough part and not too hard to get too. Went to the Hardware store, all was well, turned the Jeep off, came back out and no start. Same symptoms.
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Old 12-08-2011, 08:31 AM   #11
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I replaced CPS last night, still no start. Removed neg battery cable, replaced this morning, still no start. I poured some gas into air intake, she started right up. I just don't know if the injectors are working or the gas was entering the intake valves. I do know the ignition system is not at fault. I don't have the adapter nor the special tool to remove fuel line, as of yet. Does Jeep have a security system like GM. Had an S10 ignition security switch do this to me. Same symptoms.
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Old 12-10-2011, 12:11 PM   #12
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Well, no fuel to injectors leads me to replace the fuel pump this fine Sat. Just never had an electric pump quit pumping all at once while not running.
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Old 12-10-2011, 12:25 PM   #13
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That the fuel pump cycles on for its normal 3 seconds when you turn the ignition switch on leads me to believe it's not the fuel pump. That you have replaced your crankshaft position sensor without it helping leads me to suspect the camshaft position sensor, on the passenger side of the engine block, on top of the shaft that used to hold the distributor.
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Old 12-10-2011, 12:51 PM   #14
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That the fuel pump cycles on for its normal 3 seconds when you turn the ignition switch on leads me to believe it's not the fuel pump. That you have replaced your crankshaft position sensor without it helping leads me to suspect the camshaft position sensor, on the passenger side of the engine block, on top of the shaft that used to hold the distributor.
and if the noodle heads at the parts store can't locate it on the computer, try ignition sensor--also when i replaces mine there were more than 1-difference being the connector so if you can take the old one with you it may save you a trip(wish i wouls have known)
mine would turn over good but nothing-did get a CEL though.
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Old 12-12-2011, 11:23 PM   #15
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Well. Turns out the fuel pump quit pumping even though the pump motor did not fail. New fuel pump and all seems well. Thanks for the suggestions. Hope this thread helps someone else.
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Old 12-23-2011, 07:03 AM   #16
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Mine did the same thing but my pump won't cycle in at all. My fuses are good but there isn't power getting to the pump.... Suggestions?
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Old 12-24-2011, 10:41 AM   #17
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Well Big Green, I'd start by swapping the fuel pump relay with a known good relay, say the horn or hvac relay(make sure the horn or a/c works). Or test your relay, BACKINBLACK's Grand Prix electrical modificationsRelays.htm. To check fuel pump, disconnect fuel line at rail,(position in safe direction) jump a 12+ wire (preferably with a momentary push button in line) from the battery to fuel pump relay slot 87 located in the fuse box(power distribution center) on fender under hood.. This should bypass everything to send voltage to pump. If pump does not pump gas, it's the culprit. If it works I'd check the ASD(auto shutdown) relay. Any codes? I hope this helps.
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Old 12-27-2011, 08:40 PM   #18
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No codes... Thanks for the input..... I will give that a shot
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Old 12-30-2011, 11:00 AM   #19
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I bypassed the relay and the pump works. What does this mean
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Old 12-31-2011, 01:42 AM   #20
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Try bypassing the asd (auto shut down) relay and see if it starts. If it does, there are several possibilities. I would have to check the manual to advise on what activates the ASD. If it dont start, the ecm would be my next guess. Hope this helps.
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Old 12-31-2011, 10:04 AM   #21
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Originally Posted by BigGreen98 View Post
I bypassed the relay and the pump works. What does this mean
That doesn't really tell you much at all. The fuel pump relay is under control of the ASD (auto shut down) relay which is under control of the PCM (engine computer) and the PCM will only energize the ASD relay when the PCM is happy with all its various inputs, especially from the Crankshaft Position Sensor and, secondarily, camshaft position sensor.

At the least, you can swap the fuel pump relay with another relay like the horn relay to verifiy you don't just have a bad fuel pump relay. There are probably 3-4 relays inside the PDC that are the same that can be swapped around for troubleshooting purposes.
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Old 12-31-2011, 05:33 PM   #22
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Yea I swapped around all the relays and all are fine. I was under the assumption that the cam and crank sensors only controll timing of fuel and spark..... Which makes me think computer, but I don't wanna piss away 200 bucks on the computer and that not be the problem
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Old 12-31-2011, 05:52 PM   #23
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Without input from the CPS, the PCM won't let the engine start period.
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Old 01-02-2012, 10:35 AM   #24
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This is an exert from my Jeep manual: OPERATION - PCM OUTPUT
The ASD relay supplies battery voltage (12+ volts)
to the fuel injectors and ignition coil(s). With certain
emissions packages it also supplies 12–volts to the
oxygen sensor heating elements.
The ground circuit for the coil within the ASD
relay is controlled by the Powertrain Control Module
(PCM). The PCM operates the ASD relay by switching
its ground circuit on and off.
The ASD relay will be shut–down, meaning the
12–volt power supply to the ASD relay will be de-activated
by the PCM if:
˛ the ignition key is left in the ON position. This
is if the engine has not been running for approximately
1.8 seconds.
˛ there is a crankshaft position sensor signal to
the PCM that is lower than pre-determined values.
This is why Ithink if you bypass ADS relay and it starts, it would be the CPS( crankshaft position sensor). If it don't start, have the PCM checked. Just saying what I would do.
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Old 01-02-2012, 01:35 PM   #25
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This is why Ithink if you bypass ADS relay and it starts, it would be the CPS( crankshaft position sensor). If it don't start, have the PCM checked. Just saying what I would do.
A bad CPS would prevent the engine from starting. It will also prevent the ASD relay from engaging but if you bypass the ASD relay, a bad CPS will still prevent the engine from starting. The CPS is what provides the engine's master timing signal which is required for the ignition system to generate spark. Bad CPS = no spark.
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Old 01-06-2012, 12:08 PM   #26
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Ok but how do I bypass the asd relay. I feel like such a tard right now because I work on cars all the time but I'm chasing my tail on such a small problem
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Old 01-06-2012, 01:10 PM   #27
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Ok but how do I bypass the asd relay. I feel like such a tard right now because I work on cars all the time but I'm chasing my tail on such a small problem
Find the ASD relay (I would assume it is in the PDC) and jump the power.
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Old 01-06-2012, 02:42 PM   #28
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I just didn't know which slot to put power on to bypas it
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Old 01-07-2012, 01:48 AM   #29
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Ok, remember how I told you to bypass your fuel pump relay? You can bypass your ASD relay the exact same way. The CPS(crankshaft position sensor) is less than $20, so I'd replace that if she don't start by bypassing ASD relay. If after doing those two tests she still refuses to start, I'd have someone with a diagnostic computer to check the PCM. If she's getting fuel and air, the only thing left is spark. The way Chrysler made the plug wire system makes it very difficult to check for spark. I guess one could run a bare wire from the plug boot to a timing light to check for spark. There are three things that an internal combustion engine require: correct fuel/air mixture, and correct timing of the spark. Get those three things right and she should run. The cam position sensor could be the culprit if there is no spark. Hope this helps.
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Old 01-07-2012, 02:01 AM   #30
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guys there could be two jeeps here with the same, or similiar, problem.

http://www.wranglerforum.com/f5/new-...-120852-4.html

my 100+ thread has many ideas.....still not wprking but feel ivam near solution....

i believe my prob is goijng to be ground related.....just not sure where the groind is

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