I have an 03 4 dr 4x4 with 126,550 miles. I was on a road trip for about 500 miles. I had run some super concentrate plus thru the gas tank and had gotten 20.5 mpg. After the next fill up, I started hearing a clanking sounding from the motor. I stopped and checked oil and coolant levels both were fine. I decided to turn around. After 110 miles or so the oil turned black and smelled burnt. It also had a strong gas smell to it. No cel light came on till I parked it for the day. I had both O2 sensor detecting low circuit voltage. Also the tailpipe smells like raw fuel. At first I thought rocker or valve had broke but after checking compression removing valve covers and rotating engine by hand, all the valve train is operating properly and smoothly. Next step Would to drop oil pan and check bearing on the rods i guess. Any ideas? I have changed the oil and let it run for about 10 min but noise is still their as well as the other symptoms.

 

I haven't had any luck figuring this out. Looks like a pull out motor is in my future.

 

Run a fuel pressure & leak down test as described in the Tech Article (DIY) section. You may have experienced an FPR (fuel pressure regulator) failure which could be dumping raw fuel into the intake manifold.

 

Ok will do. Thanks for the input.