Starting problems

Tiny
CHARLES NORTH
  • MEMBER
  • 1995 JEEP CHEROKEE
  • 4.0L
  • 6 CYL
  • AUTOMATIC
  • 222,000 MILES
Vehicle cranks and if it starts it shuts off after a couple of seconds. I changed the filter and put a new fuel pump on. Same thing happens.
Monday, September 16th, 2019 AT 11:45 AM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,873 POSTS
Is there any related history that led up to this? There's two common things to consider. The first is except for diesel engines, you won't solve a running problem on a Chrysler product by replacing the gas filter. They typically last the life of the vehicle unless they rust out and start to leak. If you can hear the hum of the fuel pump for one second when you turn on the ignition switch, the pump is working. When Chrysler fuel pumps fail, they rarely stop working while you're driving. Once they're running, they continue to run until you stop the engine. Their typical failure is they fail to start up. Banging on the bottom of the gas tank often gets them going again, but the problem will occur again within the next start-up or as much as a few months later. What you described is very unlikely to be a fuel pump issue.

The first thing to look at is if the vehicle is in anti-theft mode. The engine will start and run for about two seconds, as you described, but it's running on the residual fuel pressure in the system. That gets used up in about two seconds. Unlock either front door with the key to get it out of anti-theft mode. If that doesn't work from one front door, suspect broken wires between the door hinges.

A second, real common problem is caused by disconnecting the battery. Doing so erases all the stored data in the Engine Computer. Most of that will be relearned as you drive, without you even noticing, except for "minimum throttle". The computer needs to relearn that to know when it must be in control of idle speed. A very specific set of conditions must exist for that relearn to take place. Until then, the engine may not start and run unless you hold the accelerator pedal down 1/4". If it does run, it will tend to stall at stop signs or when shifted into gear. The clue to this is the engine does stay running when you hold the accelerator pedal down just a little.

To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.
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Monday, September 16th, 2019 AT 4:59 PM

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