I have a 1999 Jeep Grand Cherokee Limit with a 6 cylinder (4.0 liter) engine. The engine is a replacement with 70k miles on it. I have driven it under 500 miles and it now is stalling every 5 to 10 miles. I’m forced to sit for 10 minutes or more before I can start it again. I got it to Advance Auto to get it diagnosed. The code came back P1494, however they didn’t have a book the read that high up. I can’t go back to the garage as they have filed for bankruptcy. If I know what and how to test the problem I think I can fix it.Also the Check Engine light is on as you could have guessed. Thank you for your help on this matter.
Okay, so drive 10 miles …things stalls …cranks fine …but no start/run. Could be lots of things. You need to verify fuel pressure at the rail when you turn the key on. Then check for spark. This is while it’s not starting, obviously.
The code is for some leak detection deal. Check all electrical and vacuum connections. Also swap like relays around in the Power Distribution Center.
When it stalls you need to find out if it is not getting fuel or spark.
You can do this with starting fluid,spark checker,timing light.
Does it have org computer or one with the new engine,was it exact same engine. I am wondering if codes are correct with different motor,maybe they are!
When it starts shut it off and turn key and see if you can hear fuel pump, you may have to stand outside of Jeep.If so when it will not start see if you can hear it.
P1494-LEAK DETECT PUMP SW OR MECHANICAL FAULT
Immediately after a cold start, with battery/ambient temperature between 40 deg. F and 90 deg. F and coolant temperature within 10 deg. F of battery/ ambient.
The state of the switch does not change when the solenoid is energized.
DTC not equal to freeze frame DTC
Wiring harness intermittent defect
Wiring harness observable defect
LDP switch sense circuit open
LDP switch sense circuit shorted to ground
Leak detection pump defective
Vacuum hose defective
Powertrain control module defective