Roadroach

My Jeep will not start. It cranks over and seems like it is going to start but will not continue to run. Checked spark with ignition tester, checked fuel pressure with gauge, fuel pump works-pumped fuel into a gas can, checked two of the injectors to see that they were getting signals, replaced spark plugs, my diagnostic tool will not connect, system worked before I changed the heater core and evaporator-no obvious unconnected plugs. Not sure what else to check. It is a 1994, 4.0L.

Bustedback

So you got gas to drain into a can, but what is the fuel pressure?

Roadroach

Fuel pressure 39 Lb.

Bustedback

You may have a bad cam or crank sensor, but check the condition of the battery first. Put a volt meter on it and see how much the voltage drops while you crank the engine over. There may be enough juice to crank the engine over, but not enough to supply the ignition and fuel pump too.

Roadroach

Changed Crank Sensor - no improvement. Using a test light poked into the wire I am seeing pulses both on Cam sensor and Crank sensor. Fuel pressure during cranking is over 40Lb. Have tried augmenting battery with charger and jumping from another vehicle. Reexamined cables/connectors to PCM and under dash, nothing obvious.

Bustedback

You may have fried the PCM by poking the wires with a test light.

Roadroach

Verified crank and cam sensors and probably PCM. Unplugged each sensor individually and tried to start the jeep. Checked the error codes and they seemed to be correct. Reconnected sensors, disconnected and reconnected battery tried to start motor and the only error code is battery disconnection error code. Right now the motor runs for a 1 to 1.5 seconds then stops. Could a bad VTA module be causing this problem and is there a way to bypass the module? Starts the same with module plugged in or unplugged.

freegdr

Motor turns ? You mean it runs then shuts off maybe ?

freegdr

Try this yet......

Roadroach

Symptoms are like the video, that something in the controls are shutting the motor off. I grounded the reset line for the Vehicle Theft Alarm module which stops the lights from flashing but does not let the car run. I have disconnected the VTA module and the systems works the same. The VTA module does not activate the horn like it is supposed to so I suspect that the module is bad and is causing the car to not start. Is there a way to bypass the VTA module? Or is there another aspect to the controls that could cause a similar problem.

rangermonroe

I just had a similar issue.

It would fire up, then shut down.

I had to take the key to the passenger door, turn it clockwise and hold for about 10 seconds, then it started right up.

Roadroach

Thanks rangermonroe. I tried your suggestion the night you posted but alas still no luck. That maneuver does reset the VTA module. I have also tried to replace the VTA module with the same results. Thanks again.

rangermonroe

Back to basics...

A turning engine needs three things to run:

Spark,

Fuel,

Air,

they need to come at the right time.

Sometime ya need to go back to the basics and work forward from there.

Good luck and keep us posted.

Not a one of us is as smart as all of us.