Good morning everyone,
I have been doing some searching throughout the forum trying to find the same problem/symptoms as I'm experiencing on my Jeep. I found a thread which describes my problem almost perfectly but I've already tried the solution from the thread and I'm still experiencing the same problem, maybe even worse now.
I have a 2005 Jeep Rubicon with 100k on it. It has the 4.0 motor and fresh oil with a mobile 1 filter. Periodically it would have zero oil pressure (at the idiot gauge) at startup. This has only happened to me when I started the jeep and it didn't matter if the motor was hot or cold. My son claims it happened to him while driving but i'm wondering now if it wasn't working when he started the jeep and the buzzer went off after he was driving. Anyway, this has only happened to me at startup. I would start the jeep and the gauge would never register pressure. After a few seconds, the buzzer would go off and the idiot light to check the gauges would come on.
I did my research in the forum and determined I would change my sending unit. I bought the following sending unit from RockAuto:
STANDARD MOTOR PRODUCTS PS404 (PS-404) Oil Pressure Sender / Switch $ 10.16
I installed it over the weekend and started the jeep. First time I started it, zero oil pressure. I turned it off, started it again...and i had oil pressure. Next day, started it...zero oil pressure. This time i let it run for maybe a minute and also raised the engine RPM's to see if it would find the signal. I never did. I turned the jeep off and immediately started it back up...and i had oil pressure.
I bought the switch from RockAuto because my local O'Reilly's said it was a special order. Now i'm wondering if i should have bought the switch from my local jeep dealer?
Another interesting note. Before i installed the new sending unit I probably had the alarm go off a total of 4 times over a few months. Since i have put the new switch in I'm guessing I've had zero oil pressure at startup 6 out of the 8 times I've started the jeep. If the jeep starts with the gauge working it always seems to work, it has never lost oil pressure/signal after it has started the 2nd time.
This is a strange one for me and i'm hopeful someone has some insight. I'm going to see if i hear anything from the forum for a few days but as of now I'm planning on ordering another sending unit from the jeep dealer and replacing the oil and filter as both are easy and relatively inexpensive.
Winter hit Kansas yesterday...this is when i need the jeep to run!!
Thanks in advance to anyone who has read this.