After a recent fuel filter/s change (10th time over the past 70K miles) on my 2017 Titan XD. My stage #1 pump started to prime and then quit mid-cycle before clearing the low fuel pressure warning. I tried several times to prime but no sound the pump was running, so I decided to drop the filter assembly. Where I found absolutely nothing wrong, so I reinstalled the filter and tried once again to prime the fuel system, with no luck. I then check and found the 20 AMP fuel pump fuse had blown. At this point, I disconnected the 12VDC power supply to the lift pump, replaced the 20 AMP fuse and tried to prime the system once again. This was done as a means of confirming if it was either the pump itself and/or a fault somewhere else. The fuse was found intact, so I re-energized the lift pump power supply, started the prime cycle and it immediately took out the fuse. It was at this point, I found myself having to order and wait nearly a week for the delivery on new $850 stage #1 lift pump.
Being the pump was shot and a new one had been ordered. I decided to tear down the pump assembly and see if could determine what might have caused the failure. As soon as I removed the (2) screws holding the housing around the internal pump and pulled the housing off. I found the cause of the failure and most likely the same cause involving most, if not all of the lift pump failures I've read online. The lower 10% of the pump's metal outer casing was covered in heavy surface rust. I'm quite certain this rust was pull up into the pump's suction inlet and caused it to bind up under load.
Here’s the issue I have with Nissan. This part is only warranty through 50K miles and/or 60 months and their service recommendations state to change/drain the water/fuel separator every 10K miles or 12 months. I personally drain and changed this filter assembly every 7K miles, or roughly twice a year on my truck and the pump still failed. I’m not sure what good a filter does in stopping debris from damaging the pump? When the pump casting is rusting out downstream of the filter and subjecting the pump’s internal moving parts to chunk of rust debris. Nissan needs to lower their recommendations on draining of water/fuel the separator and extending the warranty on the subpar pumps rusting out under their manufacture guidelines.
Attached is a picture of the stage #1 internal pump and you can clearly see the residual marking on the body of the pump near the suction inlet, even after I removed a good portion of the rust with a rag.