Jeep would not start original replaced crank sensor starts now then stalls after approx 3 sec swapped ecu with known good one still happens
These computers have anti theft it needs to be flashed to ur vin by a proprietary computer costs around 100 if u don't it will just start run for 3 seconds then shut right down
I have a 2000 cherokee that only ran for about 3 secounds and none of the guages would work. I did all of the checks I found on this web site and still nothing. Found out my battery had a dead cell, put in a new battery and so far so good. Might give that a try
I am going to assume that it will not run even if you push on the accelerator pedal?
Can you install or attach an old timing light to the spark plug wires, turn it one and try to start it. The light should flash with the engine running, but if it shuts off at time of engine die, and the engine is still spinning, you are losing spark, My suggestion is the cranks shaft sensor on bell housing.
Second, install a pressure gage on the test port on the fuel rail and watch it as you start the engine, fuel pressure should not drop as the engine dies, if it does, the pump is not working correctly. There are two modes of power to that pump, one to start and timed, for only a few seconds to prime the system, and one to run continuously. Find the wires going to the pump at the tank. Connect test light to those wires and watch what happens during crank and at stall, You should not have the pump shut off and the engine dies.
If you have spark, and fuel pump working, when did you last change the filter,,but I put that LAST.
It has to be one or the other of these.
Good Luck
You need to check the connector to the crank sensor for damage and or a poor connection.
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jumped fuel pump have pressure all times loses spark and crank sensor is new new sensor solved problem of vehicle not starting at all
My car is a 96 4.0 liter. It was running perfectly, until, one day nothing. No spark, gas and battery gauges were dead. PCM showed it was dead. Replaced it. Still no good. Found the bad Crank. Pos Sensor and replaced it. Now, the car starts like a champion, and stalls within 3-5 seconds. Remember, the only original problem was a bad CPS!!!. Hardly any time for a fuel pump, etc. to go bad, and the FP was replaced 5 yrs ago. Security system has nothing to do with it either. Tried taking the screws out of the PCM,,,possible grounding,,,didn't work either.
Breddynj, Sounds like we have the same problem, different year cars. When my CPS went bad, the ground and 5V (from the PCM (or ECM)) were grounded internally in the CPS, causing the PCM to act dead. When the CPS was replaced, the PCM and gauges came back to life. Still searching for why the car only runs (beautifully by the way) for only 3 to 5 seconds. If you solve your problem, let me know. I'll do likewise. Just disconnected the battery for 14hrs to give the PCM time to reset. Unfortunately, my original PCM (which was good) got shipped back to an outfit in Davies Florida.
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