Fuel Pressure value?

[Winfield]

Hey all, sorry if this has been posted before but the search isn’t bringing it up (that I can find). I'm trying to figure out if I have a lift pump issue in my 2015 Ram where the truck won't start or starts for a second but never gets enough RPM and the starter keeps trying to start it. The truck sounds like it's starved of fuel. I've pulled off the fuel line in front of the C4 and I am getting fuel. I've pulled the metering valve or sensor (not sure) from the C4 and the filter is clean and the fuel is clean (no metal). I have a XTOOL D8 scan tool and when I set the ignition to RUN and view live data I get a line that says FUEL RAIL PRESSURE TARGET 269.95 BAR and a second line below it that says FUEL RAIL PRESSURE MEASURED (SENSOR) 7.06 BAR. That's a pretty big delta . When I put the ignition in the RUN position the pump is timing out trying to pressurize the system. My gut (and this limited data) leads me to believe it's the lift pump but I'm not sure those two values above are supposed to match or be closer together when the truck is not running put the line is primed. The truck started to shrug on me on the road and then picked back up only to start shrugging again 30 seconds later then my electronic accelerator quit working at a four way stop because the rpm at idle dropped supper low and the engine was misfiring. Any ideas on the fuel pressure measurement? I’m not throwing any codes by the way.

 

[06 Dodge]

Have to ask when was the last time the fuel filters were changed and are you using more than 5% Bio Diesel?

 

[Winfield]

A little bit if a back story...about 2 weeks ago I filled up from nearly empty and drove about an hour. No issues but when I got back into the truck it was a super hard start and then wouldn't idle high enough for the throttle to start responding (similar to my current issuea). I opened the drain on the bottom of the filter housing and took about a cup of fuel into a clear cup. It was orange and not green. I set it next to a cup of clean dieself I had from a can and they were clearly different. I pumped the tank nearly dry into a 55 gallon barrel by cycling the ignition after routing some fuel line I had from the filter housing to the barrel. Hard on the pump I'm sure. I changed the filter, primed the line with the clean diesel I had, started the engine and blew a load of white smoke out the tailpipe and then headed to fill up with fresh diesel along with some diesel kleen. The truck ran fantastic for half a tank, ddin't miss a beat. The all of a sudden the hesitation and the stall. I had it towed home and pulled the filter again. It was till white (no conatminents) but I swapped it for another new one. I drained the tank again (same procedure - again hard on the pump I'm sure) but this time I went until it was grabbing air. I put 5 gallons of fresh diesel in, cycled the ignition about 10 times but couldn't get it to start (it tries but dies). That's when I pulled the feed lien before the CP4 and was getting diesel and pulled the metering dodad off the CP4 and had clean fuel in there. I was thinking maybe teh lift pump was shot from when I first filled up with contaminated fuel. Long story...but a number of filter changes in the last week and a half.

 

[Winfield]

I'm not sure about the bio content. I fill up 90% of the time at the same station since 2015 and have never had a problem....until the recent orange fuel.

 

[06 Dodge]

Wowzers have you checked to see if any codes show up, if so what are they and it also sounds like contaminated fuel has fur-bared something in your fuel system hope you know of a good repair shop...

 

[Winfield]

No codes unfortunately. Well except for the humidity sensor on my windshield DTC showing up....I do think the contaminated fuel might have jacked up the pump. I'm starting to think that because I had no issue for teh first half of the tank it might be something to do with the pump failing when the fuel is below a certain level. After reading all the horro stories on CP4 pumps etc I went ahead and ordered a FASS system last night. I'm going to pull the bed, drop the tank, clean out anything not replaced by the FASS install and go from there. I'm really hoping to get far more than 140K miles out of this truck. I bought the signature series that uses the pump lid and cup but puts a new straw and such inside the stock pump. When I pull it from the tank I'll bench test it a bit to see if shows anything. I'm guessing its the pump.