2003 Dodge Ram 5.7 High Fuel Pressure (90+ PSI)

[chubbysauto]

Vin#1D7HA16D53J677601
2003 Dodge Pickup 1500 5.7

Need help figuring out this problem. This is a customer's truck. They first brought it for a intermittent no-start after driving for a while. P0172 -Fuel System Rich.
I could hear the fuel pump whining. I checked the fuel pressure and it was 90+ to 100psi. Normal is around 45-60 PSI. So I figured the fuel pressure regulator on top of the actual fuel pump. I replaced the entire fuel pump with the fuel pressure regulator. Fuel pressure dropped to normal 45-60 PSI. Customer picked it up and it drove fine for a week or two.

Comes back, same whining, same high fuel pressure. Truck doesn't want to start after they drive for a bit.

So I figured the brand of product they purchased. I switched brands. Fuel pressure dropped back to normal, 45-60 PSI. Ran good for another 2-3 weeks, then same. Pump whining.

Actually, whining noise is coming from fuel pressure regulator. So I'm going to warranty this pump again, but i want to check and see WHAT IS KILLING THESE FPRs? I blew out the fuel line but there is only ONE fuel line. No return. Just one singular pressured line to the fuel rail. I also remember that the truck was having evap codes but i never got a chance to check it out. What if the fuel tank is staying pressurized? EVAP system not purging out pressure? That increased pressure is killing the FPR?

I'm lost and the customer is understanding, but i need to get this fixed.

Thanks.

 

[Hanover Fiste]

On my 2005 5.7, the normal fuel pressure is supposed to be 59 +/- 5 PSI. It also has two fuel filters; one at the bottom of the fuel pump module, and the other within the fuel pressure regulator. Did you replace the other filter, if it has one? (Not sure if the '03 setup is the same as the '05).

These are just wild guesses, but possibly the vent tube/filter abutting the filler tube is clogged, a bad fuel filler cap, clogged injector rail or bad injectors. However, I would think if the vent tube/filter is clogged, the owner would have a difficult time refueling; and if the injector rail/injectors were clogged, then the engine wouldn't run properly--just throwing these ideas out there.

 

[Grams]

Fuel pump relay issues are common with Ram gassers. ( BTDT myself, but there was no code thrown, only hard starting/lack of pressure. Fix was a TIPM fuel pump relay kit, cheap fix.)

The first thing pops into my small mind is fuel press sensor and/or relay.

 

[Daw14]

I agree with either the sensor or relay, like it is not shutting off when the desired pressure is reached.

 

[chubbysauto]

Thank you everyone for your input. I do not believe there is a fuel pressure sensor so that rules that out. I am going to try swapping the fuel pump relay with another to see if that changes anything. Thanks again. I'll keep you posted.