HELP....MY JEEP WON'T START

[BRADFORDXJ]

So heres the deal, I went to start it last night and it just keeps turning over, not even close to firing. I don't smell any fuel after a couple minutes of craking it over, so I am going to start there... I check the pressure at the rail and I get nothing, but I am not sure if I am supposed to be cranking it over while I do it. I don't want to just start replacing parts, especially since the fuel pump is not cheap..Wanted to see if you guys have any ideas I should try, before I start replacing stuff.

Thanks,

Ryan

[Clean Racing]

What year XJ is it?? If its the early Renix 87~90 there is a balast resistor on the drivers fenderwell that supply's power to the fuel pump. Check your power there with a test light. Also on the right fender liner is a block of relays, one is for the fuel pump. It also may be a CPS as well too.. the more info you give about your jeep will help. I hope some of this helps..

Scott.

[goodburbon]

check the fuel pump relay first. you should get a quick little squirt of fuel when you press in the valve after cranking on it.

if not check relay, make sure you have fuel (fuel gauges have been known to be wrong.....Mine said I had 1/8 of a tank this morning as I sputtered into the gas station and proceeded to add 19.89 gallons to a 20 gallon tank.)

then check to see that the fuel pump is getting voltage when you turn the key to run using a multimeter. if you're getting voltage in and no fuel out, it is the pump. Unless it is freezing outside and you have a bit of water in your fuel lines, If you're in the frozen part of the country You may just need to warm things up a bit.

[rpraterxj]

Unless it is freezing outside and you have a bit of water in your fuel lines, If you're in the frozen part of the country You may just need to warm things up a bit.

Good point, BUT he is in Midway City, CA... no chance of it freezing there any time soon..... BTW Midway City is in Orange County (southern CA)...


But like these guys have said, more info on the Jeep,

Then check fuses and relays, and then voltage to everything BEFORE you start replacing parts. Check the CPS before the fuel pump.

Good luck!

[gigage]

X2 on the cps, seems like alot of talk about that lately. check this out, good luck
http://www.floridajeepers.net/viewtopic.php?t=20947

[4xSanta]

Midway City is the key to this problem,you need to call the Police and report the guys that stole your gas last night and put it in there low rider so they could do a drive by

[MJR]

I see it's a 96.

First does the tach register RPM when you crank the engine over?

If you just have someone cycle the key from off to on (don't crank it) do you have fuel then?

Have you checked for any codes? By cycling the key on/off/on/off/off counting the check engine lamp flashes.

[rpraterxj]

I see it's a 96.

I guess looking at someone's profile would have answered that one, huh??

Glad to see you are alive Mike... hope you're feeling better!

[MJR]

I guess looking at someone's profile would have answered that one, huh??

Glad to see you are alive Mike... hope you're feeling better!

Yup. Better today, yesterday was hell.

[BRADFORDXJ]

Yeah, it is a 96 auto.....I have no tach..it is the cheapy, just the idiot lights and spedo.....

[MJR]

You can check the other things I listed. For the crank sensor test try turning the key on, pressing the fuel rail shrader to bleed off any pressure, then crank it and see if you had pressure.

The fuel pump will turn on for about 5 seconds when the key is turned on, if the engine controller sees a crank signal it will keep the fuel pump running.

[old_man]

The CPS will not keep the fuel pump from running.

As soon as you turn on the key the pump should start up at least for a few seconds and you should have fuel pressure. Crawl under and pull the power plug on the fuel pump back by the tank. Check for voltage when the key is first turned on. If no voltage, the problem is electrical. If there is voltage and you don't hear the pump, you have a pump problem. If you hear the pump, you may have a loose hose between the pump and the bracket, inside the tank.

[MJR]

The CPS will not keep the fuel pump from running.

Did you read what I wrote?

The fuel pump will turn on for about 5 seconds when the key is turned on, if the engine controller sees a crank signal it will keep the fuel pump running.

Maybe I should have said it this way.

The fuel pump will turn on for about 5 seconds when the key is turned on, after that if the engine controller sees a crank signal it will keep the fuel pump running.

[SBrad001]

Yeah, it is a 96 auto.....I have no tach..it is the cheapy, just the idiot lights and spedo.....

Check your 30 amp fuse in the engine compartment's fuse box. It's a little tiny fuse in the the middle of the fuse block. It's the fuse for the entire ignition system, from O2 sensors, to fuel rail and injectors, to the coil and distributor. Check it.

[BRADFORDXJ]

there we go, I would love for it to be a $.30 fuse instead of the $130 fuel pump....I was even checking the fuel gauge to make sure somebody didn't steal my gas....they tried to steal my daughters power wheel jeep out of the back of my car, I guess it was a good thing the retard couldn't figure out how to fold the rear seat down with 2 carseats in it : )

[MJR]

Any electrical problem should always be started by checking all the fuses even if they don't seem to apply. Also sometimes overlooked are missing fuses which I have seen before.

Next you should cycle the key off/on a few times just to make sure that the fuel didn't drain back from the fuel lines when it was off (bad check valve). This would tell you where to look.

You could also pull the fuel pump relay and check for battery +12V on one pin. Then you could jumper it to the output to see if the pump runs.

I have had a friends XJ die while driving and it seemed like a fuel pump until we took it out and found this rubber plug got sucked into the inlet. It came off the prefilter sock when it was floating around in the tank.

http://gotgroceries.net/TierraDelSolDesertSafari305/photos/photo74.jpg
http://gotgroceries.net/TierraDelSolDesertSafari305/photos/photo76.jpg

[BRADFORDXJ]

Well, it is not the fuel pump...I could've sworn it was. So I wasted $140 for nothing. I checked all the fuses, they're all good. I seem to have a little more pressure at the rail but the dang thing still will not start

[MJR]

The CPS will not keep the fuel pump from running.


Actually Yes it can. The first clue is it's a 96. Second clue the fuel pump does not turn on when the ignition key is turned on or cycled.

Now if you are throughly confused let me explain what happened when I went over to look at it.

First things first I plug in the DRB III (factory scan tool) and try to communicate with the engine controller but get No Reponse. Start with the basics, fuses good, ignition switch looks good, so now on to the wiring diagrams (not thinking about prior experience with Grand Cherokees). Unplug the engine controller and check feeds/grounds directly at the engine controller connector, battery feed good, ignition switched feed good, and 2 grounds good.

Huh seems like a bad engine controller right? Wrong.

Ok here is the next step. Unplug throttle position sensor (TPS), manifold pressure sensor (MAP), upstream oxygen sensor (O2), downstream oxygen sensor 96-01 (O2), camshaft position sensor (CMP), and crankshaft position sensor (CKP). Try again to communicate with engine controller and what do you know I can now talk to it. Plug everything back in except for the crankshaft position sensor and I can still communicate with controller. Plug the crankshaft position sensor back in and I am no longer able to communicate with engine controller.

Problem bad crankshaft position sensor.

Reason is the JTEC (Jeep/Truck Engine Controller) which was first used in 96 (used from 96-01 in XJ's) is not as forgiving when inputs/outputs are shorted as the previous SBEC (Single Board Engine Controller) used from 91-95.

When the crank sensor shorted internally (or for that matter any other sensor that uses the 5V provided by the engine controller) it pulled down the 5V reference provided by the engine controller which caused the controller not to power on (or for that matter communicate with the scan tool) when the key was turned on. Therefore the fuel pump wouldn't turn on when the key was cycled because the engine controller didn't turn it on.

I should have remembered the Grand Cherokees I had seen this on before since it would have saved me some time but in the end it all worked out. I was glad to help diagnos the problem and as soon as he gets a new crank sensor it will be up and running again.

[corbinafly]

Actually Yes it can. The first clue is it's a 96. Second clue the fuel pump does not turn on when the ignition key is turned on or cycled.

Now if you are throughly confused let me explain what happened when I went over to look at it.

First things first I plug in the DRB III (factory scan tool) and try to communicate with the engine controller but get No Reponse. Start with the basics, fuses good, ignition switch looks good, so now on to the wiring diagrams (not thinking about prior experience with Grand Cherokees). Unplug the engine controller and check feeds/grounds directly at the engine controller connector, battery feed good, ignition switched feed good, and 2 grounds good.

Huh seems like a bad engine controller right? Wrong.

Ok here is the next step. Unplug throttle position sensor (TPS), manifold pressure sensor (MAP), upstream oxygen sensor (O2), downstream oxygen sensor 96-01 (O2), camshaft position sensor (CMP), and crankshaft position sensor (CKP). Try again to communicate with engine controller and what do you know I can now talk to it. Plug everything back in except for the crankshaft position sensor and I can still communicate with controller. Plug the crankshaft position sensor back in and I am no longer able to communicate with engine controller.

Problem bad crankshaft position sensor.

Reason is the JTEC (Jeep/Truck Engine Controller) which was first used in 96 (used from 96-01 in XJ's) is not as forgiving when inputs/outputs are shorted as the previous SBEC (Single Board Engine Controller) used from 91-95.

When the crank sensor shorted internally (or for that matter any other sensor that uses the 5V provided by the engine controller) it pulled down the 5V reference provided by the engine controller which caused the controller not to power on (or for that matter communicate with the scan tool) when the key was turned on. Therefore the fuel pump wouldn't turn on when the key was cycled because the engine controller didn't turn it on.

I should have remembered the Grand Cherokees I had seen this on before since it would have saved me some time but in the end it all worked out. I was glad to help diagnos the problem and as soon as he gets a new crank sensor it will be up and running again.
Mike,

Good to know!

Kyung

[rpraterxj]

Actually Yes it can. The first clue is it's a 96. Second clue the fuel pump does not turn on when the ignition key is turned on or cycled.

Now if you are throughly confused let me explain what happened when I went over to look at it.

First things first I plug in the DRB III (factory scan tool) and try to communicate with the engine controller but get No Reponse. Start with the basics, fuses good, ignition switch looks good, so now on to the wiring diagrams (not thinking about prior experience with Grand Cherokees). Unplug the engine controller and check feeds/grounds directly at the engine controller connector, battery feed good, ignition switched feed good, and 2 grounds good.

Huh seems like a bad engine controller right? Wrong.

Ok here is the next step. Unplug throttle position sensor (TPS), manifold pressure sensor (MAP), upstream oxygen sensor (O2), downstream oxygen sensor 96-01 (O2), camshaft position sensor (CMP), and crankshaft position sensor (CKP). Try again to communicate with engine controller and what do you know I can now talk to it. Plug everything back in except for the crankshaft position sensor and I can still communicate with controller. Plug the crankshaft position sensor back in and I am no longer able to communicate with engine controller.

Problem bad crankshaft position sensor.

Reason is the JTEC (Jeep/Truck Engine Controller) which was first used in 96 (used from 96-01 in XJ's) is not as forgiving when inputs/outputs are shorted as the previous SBEC (Single Board Engine Controller) used from 91-95.

When the crank sensor shorted internally (or for that matter any other sensor that uses the 5V provided by the engine controller) it pulled down the 5V reference provided by the engine controller which caused the controller not to power on (or for that matter communicate with the scan tool) when the key was turned on. Therefore the fuel pump wouldn't turn on when the key was cycled because the engine controller didn't turn it on.

I should have remembered the Grand Cherokees I had seen this on before since it would have saved me some time but in the end it all worked out. I was glad to help diagnos the problem and as soon as he gets a new crank sensor it will be up and running again.


:yelclap: :yelclap: :worship: :worship:

[BRADFORDXJ]

THAT'S WHAT I'M SAYING......MIKE YOU ARE THE MAN THANKS AGAIN !!!!:party:

[Lady XJ]

Careful,the Jeep god's head is swelling.............;)THAT'S WHAT I'M SAYING......MIKE YOU ARE THE MAN THANKS AGAIN !!!!:party:

[MJR]

The CPS will not keep the fuel pump from running.


Actually yes it can X2 now.

Problem #2. 01 XJ was running and suddenly died and won't restart. No fuel pressure, check engine lamp on, instrument cluster gauges not working, odometer displaying "No Buss" message, and unable to communicate with a scan tool.

Lucky for the owner he had my phone # and I had just diagnosed the 96 one. Failure was the same as BRADFORDXJ's. Bad crank sensor pulling down the 5V reference from the PCM which in turn pulled down the entire data buss affecting the cluster/gauges (97-01). New crank sensor and runs again.

[XJ6]

Thanks to the info above my '96 runs again. :yelclap:

This morning I got in to go to work and nothing - it cranked but wouldn't start and the loss of dash warning lights made me think there was more to it than a sensor fault, checked circuits to pump and ASD relays good EXCEPT had no turn on signals from PCM, had good grounds to PCM, time to do a search on NAXJA - found this thread on page 7, unplugged crank sensor WOW dash warning lights are back and OBD II reader now communicates, replaced crank sensor and the XJ lives again. Thanks to posts like this membership in NAXJA is more than worth the small fee. Thanks for sharing this info, was a great help.

Mike

[MJR]

Thanks to the info above my '96 runs again. :yelclap:

This morning I got in to go to work and nothing - it cranked but wouldn't start and the loss of dash warning lights made me think there was more to it than a sensor fault, checked circuits to pump and ASD relays good EXCEPT had no turn on signals from PCM, had good grounds to PCM, time to do a search on NAXJA - found this thread on page 7, unplugged crank sensor WOW dash warning lights are back and OBD II reader now communicates, replaced crank sensor and the XJ lives again. Thanks to posts like this membership in NAXJA is more than worth the small fee. Thanks for sharing this info, was a great help.

Mike


Glad you found it and it helped. Man I really need to do a frequent problem list, maybe when I redo my web site.

[cal]

Glad you found it and it helped. Man I really need to do a frequent problem list, maybe when I redo my web site.

I was just about to email you and ask where your website went? I wanted a picture from it for another thread.

[MJR]

I was just about to email you and ask where your website went? I wanted a picture from it for another thread.

I know it's my stupid web host company. They have been a problem off/on.

[Jump This]

Glad you found it and it helped. Man I really need to do a frequent problem list, maybe when I redo my web site.


Book

[XJ6]

Glad you found it and it helped. Man I really need to do a frequent problem list, maybe when I redo my web site.

A sticky in the OEM forum with links to frequent and or strange problems could be really helpful and possibly easier to find answers than searching (do a search for "no start" to see how much info comes up - a lot of it should be "no cranking" or "poor fueling" etc.). Just a thought, I of course am not the one to do this as I'm still a noob at the Jeep systems and they are a bit different than the Jaguars I deal with every day.

Again thanks for sharing this info :worship:

Mike