Cranks but will not start

Tiny
KENKELL72
  • MEMBER
  • 2000 JEEP GRAND CHEROKEE LAREDO
  • 4.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 152,000 MILES
I went out to start my Cherokee this morning (drove it yesterday it was fine). It cranked but would not start. The key with the line through it keeps coming on and staying on steady not flashing and the fuel gauge is not moving at all.
Thursday, December 21st, 2017 AT 2:43 PM

1 Reply

Tiny
HARRY P
  • MECHANIC
  • 2,291 POSTS
Do you hear a humming sound coming from the fuel tank when you turn the key on (but not to the crank position)? You may have to get a helper to turn the key on and off while you get on the ground and listen for that sound. If you hear it, then I would start by taking that key to the dealership and having it checked. If it's the key that I think it is, then it has a security code programmed into it. I think that with that light staying on, it's telling you that there is something wrong with that key.

If you do not hear the humming sound, try tapping on the bottom of the tank with a hammer or other blunt object immediately after the helper turns the key on. If you then hear the pump come on, then you need a new fuel pump. Simple as that. You freed up the brushes in the electric motor inside the pump. This is a very temporary fix (might give you an hour or two of running time).

If you still do not hear the pump come on, then you need to check the fuses. There are fuse box diagrams attached below. The first fuse box to look at is the power distribution center, which is under the hood, right behind the battery. In particular, look at the fuses for "fuel pump", "ECM/TCM," "PWR Train," and "ENG Ign." ALLData's description (slightly confusing) is in the last image attached below.

Just because the pump receives power and comes on, doesn't mean that it is pumping enough. We will circle back to checking the pressure output later on, if necessary.

If the pump is coming on, the next easy thing to check is for sparks. You can do this with a tester that's available at AutoZone or any other auto parts store. Here is a link for one on Amazon: https://www.amazon.com/Lisle-20610-Inline-Spark-Tester/dp/B0002STSC6/ref=sr_1_3?ie=UTF8&qid=1501325755&sr=8-3&keywords=spark+tester

Basically, you pull the plug wire off of the ignition coil (also pictured below) and plug in this tester between the coil and the plug wire. Then get someone to turn the key while you observe it. If it flashes, then you have spark. Check all of the cylinders.

Let us know and we'll go from there. There are more advanced tests that you can do for free or very cheap. We will go through them if needed.

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Friday, December 22nd, 2017 AT 5:04 AM

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