Ill start by saying I have a 1999 Cummins 5spd with 108,000 miles on it. No issues thus far.

However, tonight I went to refuel and the pump that I always go to was pumping oddly slow, it seemed weird to me so i stopped pumping. I put 9 gallons in my tank before stopping the pump and getting the rest of my money from the clerk. When I started my truck the check engine light went on (it never has before). I wanted to get my truck home because I only live about a mile from the station. While driving home I noticed my rpm gauge go from 1800 rpm's down to 0 quickly, it did this about 3-4 times then went back to normal.... the weird thing is my engine still remained at the same speed and sound when the gauge was at zero... so I didn't have any power loss the needle was just dancing.

Im not sure if the slow pump was due to the fact that it's 7 degrees here in Detroit Michigan or if the tank was almost empty.

note: I run an anti-gel/water separator supplement to my fuel every time I fill up and my "water in fuel" light did not come on. Also my fuel pressure remained at its normal 10-11 psi.

Any input would be greatly appreciated

 

Well never mind turns out it had nothing to do with the fuel the code came back as P0336 -Crankshaft Position Sensor. I plan on replacing it once the part gets to my local Cummins dealer. It just seemed too strange that the CEL would come on right after I had issues with that particular pump.