04 xlt 4.0 low fuel pressure

[Captngeetch]

some background. Truck ran fine, turned on the a/c and after a short time she started to sputter, lost power and wanted to stall. Threw the Fuel Rail sensor code when I read it. I put in a new one (fun job) and took her fpr a test ride. Ran perfectly with and without the a/c. Parked and went to drive the next day and she has zero power, sputters, runs too rich and wont rev past 3k. When I did the fuel rail sensor there was ZERO pressure when I removed it. Thought that was odd, but the test ride went perfect so I ignored it. Today I changed the fuel filter and again ZERO pressue when I removed it. I didnt relieve the pressure on purpose so I could see it it had pressure. It throws the fuel rail pressure code and a sensor 1 bank 2 O2 Rich code. I am baffled. Its not the fuel pump reset, tried that and besides it does start. Am I looking at dropping the fuel tank and replacing the fuel pump or could it be something else ? I would think if the fuel pump went it wouldn’t start at all. Could it be the cats ? there is also an exhaust leak, but its had that for months without causing any issues.

Any help is GREATLY appreciated. It’s our only vehicle since the ‘03 XLT threw a bearing. I should also say that i did a tranny swap in the ‘04. It’s the one from the ‘03. That was last year and has run great since. Doubt it has anything to do here.

 

[imp]

some background. Truck ran fine, turned on the a/c and after a short time she started to sputter, lost power and wanted to stall. Threw the Fuel Rail sensor code when I read it. I put in a new one (fun job) and took her fpr a test ride. Ran perfectly with and without the a/c. Parked and went to drive the next day and she has zero power, sputters, runs too rich and wont rev past 3k. When I did the fuel rail sensor there was ZERO pressure when I removed it. Thought that was odd, but the test ride went perfect so I ignored it. Today I changed the fuel filter and again ZERO pressue when I removed it. I didnt relieve the pressure on purpose so I could see it it had pressure. It throws the fuel rail pressure code and a sensor 1 bank 2 O2 Rich code. I am baffled. Its not the fuel pump reset, tried that and besides it does start. Am I looking at dropping the fuel tank and replacing the fuel pump or could it be something else ? I would think if the fuel pump went it wouldn’t start at all. Could it be the cats ? there is also an exhaust leak, but its had that for months without causing any issues.

Any help is GREATLY appreciated. It’s our only vehicle since the ‘03 XLT threw a bearing. I should also say that i did a tranny swap in the ‘04. It’s the one from the ‘03. That was last year and has run great since. Doubt it has anything to do here.

@Captngeetch
There is a fuel pressure relief valve built into the pump assembly, in the tank. It is put there to protect the pump from over-pressure, in the event of failure of the fuel pressure drive module, which is built into the PCM beginning in '04. Prior, it was a separate module, and is used only with the returnless fuel system. If that relief valve is faulty, and the Fuel Rail Pressure and Temperature Sensor is working properly, it will be running the pump full-bore and not getting adequate fuel pressure to the engine. The pressure relief is mechanical, and the PCM has no way of producing a code to that effect, so throws a code for the pressure sensor.

Your code for rich fuel mixture would seem to be unrelated. You seem to have covered the bases checking filter, etc. I would replace the pump assembly, based on the symptoms. Also, I could be wrong. Where faults not directly detectable by electronic means occur, it becomes something of a "craps shoot". imp

 

[Captngeetch]

Thanx for the reply. I kind of figured this was gonna be the answer. Was hoping it was possibly an external module of some sort that I didn't know about in the fuel system. The lack of pressure led me to believe I would be dropping the tank. Ugggg. Well, i dropped the tank in my '03 to drain it fully and remove any salvagable parts..and am bummed to learn the fuel system changed in 04. And there are actually 2 different assemblies for 04.

Ordered the parts today..total cost was $112 shipped for a Delphi assembly. Of course it was the more expensive of the 2 different models. Motorcraft branded is close to $400. The Delphi comes with a Lifetime warranty, so nothing to lose except my time I guess.

Thanx again for the insight.

 

[Captngeetch]

Well....that wasn't it. Car acted the same after the 3hr job. Same codes. Cleared the codes and now it struggles to even start. Thought it might be the PATS system. Saw a code refrencing it, but once cleared it didn't return. Fuel is not making it to the engine apparently. Was thinking of trying to clean the fuel injectors and rails, maybe they are clogged. Any further hints as to what would cause no fuel pressure would be GREATLY appreciated.

Changed already: Fuel Rail Sensor, Intake Gaskets, Fuel Filter, Fuel Pump (entire assembly incl strainer).

 

[imp]

Well....that wasn't it. Car acted the same after the 3hr job. Same codes. Cleared the codes and now it struggles to even start. Thought it might be the PATS system. Saw a code refrencing it, but once cleared it didn't return. Fuel is not making it to the engine apparently. Was thinking of trying to clean the fuel injectors and rails, maybe they are clogged. Any further hints as to what would cause no fuel pressure would be GREATLY appreciated.

Changed already: Fuel Rail Sensor, Intake Gaskets, Fuel Filter, Fuel Pump (entire assembly incl strainer).

@Captngeetch
At this point, I would get a fuel pressure reading at the fuel rail. Jury-rig a gauge connection if necessary. A clog in the rails is highly unlikely, unless the filter element had ruptured, allowing foreign materials into the rail. If rail pressure is low, check pressure back towards the tank. Possibly at inlet to filter. What exactly is the fuel rail code being thrown? I've assumed from the start it is the "Fuel Pressure and Temperature Sensor.........". Or is it some other code? imp

 

[Captngeetch]

@Captngeetch
At this point, I would get a fuel pressure reading at the fuel rail. Jury-rig a gauge connection if necessary. A clog in the rails is highly unlikely, unless the filter element had ruptured, allowing foreign materials into the rail. If rail pressure is low, check pressure back towards the tank. Possibly at inlet to filter. What exactly is the fuel rail code being thrown? I've assumed from the start it is the "Fuel Pressure and Temperature Sensor.........". Or is it some other code? imp

Same code I had from the start. Fuel Rail Pressure Sensor. I still have the old one, I will cut the old filter open today and look. The fuel that came out when I changed it was really dirty. Will also see if I can get a gauge on the fuel rail bleeder. Will have to rig something. I use ScanXL Pro to read codes, it does live data. Will see if I can read it thru that too.
Thanx for the help. This had me baffled and I hate just throwing parts at it

 

[imp]

Same code I had from the start. Fuel Rail Pressure Sensor. I still have the old one, I will cut the old filter open today and look. The fuel that came out when I changed it was really dirty. Will also see if I can get a gauge on the fuel rail bleeder. Will have to rig something. I use ScanXL Pro to read codes, it does live data. Will see if I can read it thru that too.
Thanx for the help. This had me baffled and I hate just throwing parts at it

@Captngeetch
Please be aware that there is a big difference between Fuel Rail Pressure Sensor, and Fuel Rail Pressure and Temperature Sensor. The former is older, used with return-type fuel systems. Returnless uses the other, which provides fuel TEMPERATURE data also. They are distinguishable from one another by the temperature type having a wiring connector, the other does not. imp

 

[Captngeetch]

The filter was intact. The sensor I changed is on the fuel rail and only has a vacuum line and electric connector. Are you saying there is another one ? Or just that the 04 is a returnless system, I know there is a difference, I have an ‘03 that is now a parts car and was bummed to see I couldn’t cull the parts from it for the 04.

 

[imp]

The filter was intact. The sensor I changed is on the fuel rail and only has a vacuum line and electric connector. Are you saying there is another one ? Or just that the 04 is a returnless system, I know there is a difference, I have an ‘03 that is now a parts car and was bummed to see I couldn’t cull the parts from it for the 04.

No, just one, with the vacuum line and electrical connector, first used in '04 with 4.0L. Don't know about the V-8. imp

 

[Captngeetch]

Sorry to have to bring this back up but still not fixed. I replaced the fuel rail pressure sensor and she started and ran great for the test ride, then went right back to the same as before. I replaced every part in the fuel system and still the same. I decided to check the FRPS again and sure enough the diaphram was blown out. Replaced it again and the same result. I cheaped out on the sensor and bought the cheapest available ($15). Is that my issue ? Do I need to breakdown and buy the namebrand ($130+) ? Or is there another part that would cause the sensor to blow out ? I know the sensor is bad, fuel is getting into the vacuum lines and I can think of any other way that would occur ??

Any insight would be GREATLY APPRECIATED. It's our only vehicle and we have been stuck withoutmone for about 2 months now

For reference..I have changed the FRPS twice, new fuel pump, filter, vacuum lines, the vapor sensor near the fuel tank, the one up front as well as the Fuel Pump Control Module.

 

[imp]

Sorry to have to bring this back up but still not fixed. I replaced the fuel rail pressure sensor and she started and ran great for the test ride, then went right back to the same as before. I replaced every part in the fuel system and still the same. I decided to check the FRPS again and sure enough the diaphram was blown out. Replaced it again and the same result. I cheaped out on the sensor and bought the cheapest available ($15). Is that my issue ? Do I need to breakdown and buy the namebrand ($130+) ? Or is there another part that would cause the sensor to blow out ? I know the sensor is bad, fuel is getting into the vacuum lines and I can think of any other way that would occur ??

Any insight would be GREATLY APPRECIATED. It's our only vehicle and we have been stuck withoutmone for about 2 months now

For reference..I have changed the FRPS twice, new fuel pump, filter, vacuum lines, the vapor sensor near the fuel tank, the one up front as well as the Fuel Pump Control Module.

@Captngeetch
The fuel pressure regulator in the tank should protect the entire fuel system from excessive pressure, which in theory might blow out diaphragms, if it went too high. Without knowing the actual pressure being delivered, I think I would buy and install the name-brand Pressure/Temperature Sensor. imp

 

[Captngeetch]

Solved

Thought I would update this, albeit 2 months later. It turned out to be the Fuel Pressure sensor. And I learned to NEVER buy aftermarket Chinese parts..well at least not this particular sensor. After install every other part in the system, after it ran fine on the test drive, the next start would give me fuel in the vacuum lines again. I finally broke down and bought the Bousch part, took off the plenum for the third time and BAM...it was fixed. The Chinese parts do not have the ball bearing in the sensor that the Bousch has and it kept blowing out the diaphram. On the upside, she has an all new fuel system, including the in-tank fuel pump.

So anyone searching the forums and has these symptoms...do yourself a favor and spend the extra $$ on the OEM part..you will save yourself lots of time and headaches.

Also DO NOT forget to change the oil BEFORE running the engine. And change the oil at least TWICE. You do not want to run her with fuel in the oil. I changed it before starting after sensor install and then again after a short drive.