Not sure if this is the right place for this but I'll give it a shot and this just started a few days ago. First of all it is a 2004.5 Ram 3500, 5.9L HO with a Fass lift pump. When I turn the key in the ignition to the "run" position the pump (Fass) now runs about 25 seconds, when it used to run about a second or 2. It is also very loud.

I can start the truck anytime during this 25 second run-up and then the pump will continue to run and stay very loud after start-up. If I let the pump run until it shuts off I can start the truck and the pump will not be running...initially. Then it will sporadically go on and off (again quite loud) but if I hit the accelerator as soon as it starts, it will stop...and then in about 10-15 seconds it will do it again.

Sounds like the pump is going but, then again, it could be a filter issue or tank issue. I checked the lines at the pump and they seem to be on clean with no air suction issues.

 

By the way, through all of this the truck starts and runs fantastic. High or low end it responds immediately with no hesitation. I have an EDGE CTS that I use to monitor a few things including fuel rail pressure. The FRP is still showing between 6.5 and 7 kpi during idle and responds accordingly to acceleration.

Thoughts? I am supposed to take a short trip (about 120 miles) on Monday and have little time to do anything with this.

The amount of time it's running will be ECM controlled or caused by a faulty relay. I'd check/swap the relay first.