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Discussion Starter #1
Ok, posting this question for hubby. He's planning on ripping the jeep apart(again) as soon as he gets home from work and is hoping for some ideas. Did some moderate wheeling last weekend, including some water crossing. Monday he jumped in the jeep(99TJ), it started, drove 10 feet and died. Seemed to not be getting fuel. Poured some gas into the top of the engine(manifold?....sorry I'm not a wrencher by any means!) and the jeep would start, but not continue running. At that point he knew that he had spark, but not fuel. Everyone thought it had to be the fuel pump. He replaced the fuel pump yesterday to no avail... and worse yet, now it doesn't have spark and there doesn't seem to be power to the fuel pump. He double checked all wiring. Switched relays around and all are working. Any ideas? Grasping at straws he's probably going to install a new coil, but it just doesn't make sense to me that there would be spark one day and not after the new fuel pump was put in. Any thoughts on what could have went wrong with the install or any idea what else could be going on? Thanks guys!!!

Tami
 

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Discussion Starter #3
Thanks.. searching "crank trigger" posts now... makes sense from what I've read so far...
 

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Does the fuel pump cut on and off when you turn the key to the start position? If yes then you should look on your fuel line under the hood there is a schrader valve there and when you press it (like deflating a tire) it will spew gas. Let the pressure out and the gas following it into a large shop rag. Now turn the engine over two to three times and do the same. If there is gas coming out again you have a working fuel pump. If not you have comfirmed the pump to be the issue.
 

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Discussion Starter #5
Ok, it's not the Crank Position Sensor. Replaced that tonight, no change.

We can not hear the fuel pump come on when the key is turned to the start position. When the valve is pressed the first time some gas comes out. Beyond the first time it doesn't. Did the same yesterday.

Any other ideas? :confused:
 

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pump will only power for about 2 seconds when you first turn the key on, then it goes into standby mode until the Jeep is started. Did he replace the fuel filter when he did the pump?
 

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I may be way off, but doesn't the "sentry key" (sp) kill the motor if it doesn't get a signal?
 

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First, you need to solve the fuel problem. As noted above, the fuel pump runs for 2 seconds and then goes to standby. This is for a couple of reasons...it pressureizes the fuel rail for starting....and it keeps the system from pumping gas when the engine is not running (if you are in an accident and the engine dies, you don't want the fuel pumpt to keep running).
There is a relay in the enigne compartment that powers the fuel pump. Make sure it energizes. If not, trace back from there. If it does...then use a voltmeter to confirm you have voltage going to the fuel pump. Going through water can cause connection problems. When you press on the valve stem on the fuel rail...gas will blast out if you have proper pressure.

I would also have a look in the dist. It provides the cyl #1 TDC signal....this, along with the CPS tell the computer when to fire the plugs. If you have water in there, it could cause a problem.

Good Luck
 

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I agree with DDawg, pull the cap on your dist and check for water.

Also, did he properly prime the system when he replaced the fuel pump? I have an external pump which makes that mandantory... if his is submerged intank, please disregard
 

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Discussion Starter #13
Rad, thanks for the link to the other thread. I see at least a few things to try from there. So, there is a ASD relay and a ASD fuse? All relays work, but I don't think he's specifically looked for an ASD fuse. He supposedly checked all the fuses, though, so who knows? I'll run it by him with the other ideas from your post.

Dawg, thanks. I know the relay is working... I got to sit in the jeep honking the horn numerous times as he switched them around <gg> I know he was out there playing with his voltmeter, but I don't know if he specifically checked to see if he had voltage going to the fuel pump. I'm pretty sure he thinks he doesn't, but not sure how he determined that. Will have him check the distributer if he hasn't already. Thanks.

Stroker, the fuel pump is submerged in the tank. Thanks for trying to help, though! Really appreciate any ideas at this point! He's frustrated beyond belief .

Tami
 

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water crossing.. then dead jeep...

have you checked to make sure its actually getting FUEL and not just a bunch of water.
 

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me too...

My 4.2 I6 is converted to EFI with a MOPAR kit. The 33 gal Aero tank was so badly mashed up, we replaced it w/ a new 33 gal Aero tank. Since i was doing the tank, lets swap in the new (spare) in line fuel pump, new filters and lines, etc.

Go to fire it up and it will fire for a brief moment, then sputter and die. I screwed on a EFI fuel pressure guage (from Hesco) and with about 3' of hose, can tape the guage to the drivers mirror. It was immediately apparent the MOPAR computer, that powers the pump for about 2 seconds, was not completely pressurizing the line, only up to about 12psi. with that little psi, it'll fire, sputter and die.

So the solution is to manually run or 'bump' the pump-- i used a 12VDC power source and manually ran the pump till it hit 32 psi. This is easy if u have an external pump. Disconnected the jumper wires and she fired right up and runs fine to this day.

Once last year on rubicon, a driver with a dead TJ--could not get sufficient power to the fuel rail. We mcgyvered in an in line pump, manually 'bumped' it to 32 pounds and it started right away. This after the other helpers tried all sorts of wild and unsuccessful ideas to get it running.

So lesson here, even if all the connections look fine, etc., reliance upon the computer to properly pressurize the line will not work. repeated key on/off/on/off won't do it either. One must manually overide the pump control unti its pressurized. This will be the case especially if u depressurize the line via the schrader valve.

The EFI guage from Hesco saved my bacon, and others in same situation, many times. It's like $50.00 and worth every penny to help isol;ate ur fuel delivery issues, since w/out it, u don't know if the rail is getting proper psi.

JMO


mb
 

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Does the TJ have a "rollover" fuel pump shutoff switch?

I know those can be tripped in cars.

I ask because my buddy has a similar problem, and it died right after landing hard on a rock.
 

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[

I know the relay is working... I got to sit in the jeep honking the horn numerous times as he switched them around <gg> I know he was out there playing with his voltmeter, but I don't know if he specifically checked to see if he had voltage going to the fuel pump. I'm pretty sure he thinks he doesn't, but not sure how he determined that. Will have him check the distributer if he hasn't already. Thanks.


Tami[/QUOTE]

Tami, by "moving" the relays, you have checked them, but not the input signals from the ECM or powe to the relays from the PDC(underhood fuse panel). You need to check the ASD and fuel pump relay. If you place your finger on them while somone turns the key on, you can "feel" them click which means they are working. How deep was the water you went through? Was it at a high rate of acceleration? Start by disconnectiong the neg batt cable, unplug each of the 3 connectors on the ECM(brain) and look for water or mud on contacts. The ECM is sealed so no water can get inside it but the PDC is easily contaminated. Also disconnect the C103 and C104 connectors to check them also. They are the two located in the middle of the firewall up by the hood. One is grey and the other is black. Look at the ECM ground wires on the firewall for mud or loose connections. If you cant find the problem, you can e-mail me for more suggestions [email protected] Evan
 
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