patyroach
New Member
- Joined
- April 22, 2019
- Messages
- 3
- Reaction score
- 0
- Year, Model & Trim Level
- 2004, Explorer, NBX 4.6l
Greetings all,
I just finished a month long battle with a fuel delivery issue on my wife's 2004 Explorer 4.6l
She called me at work to rescue her from the side of the road. After an intense tow trip home in the snow (her first go at being towed redneck style as all my usual suspects were working) I parked the vehicle in my buddy's garage and the fun began.
Initial diagnosis: Fuel pump. I tested power from the cable to the pump to verify it had power, which it did. I ordered a $60 pump from rock auto and played the waiting game for a week. Installed the pump (which included a fancy new hole in the floor upgrade located behind the front passenger seat to avoid dropping the tank) on arrival and the ol girl barked right off. I took it for a test spin to check on my old man's place as he's on vacation and after ravaging his fridge of whatever bottom shelf liquids I could find I found the truck wouldn't start. After doing the rap on the fuel pump trick it barked off again and I headed back to my buddy's garage for what would prove to be an epic battle.
I found that I had somehow lost ground all-together. I pulled the pump and ran it directly from battery 12v and the pump worked, as did the old one. I have worked as an industrial E&I controls tech for years so basing what I know about controls in that world I spliced into the pump harness and made my own ground to the frame assuming my wire had opened up somewhere along the way. This fixed the issue. Take 2 on a test drive. I drove again to my dad's place and after letting the vehicle rest for a bit found it was dead in the water. I got the original pump and threw it in and headed back to my buddy's garage for some more fun.
I hooked up the code reader and it showed a p0191 fault (fuel rail over pressure). I ordered a new rail pressure sending unit and waited yet again. When it arrived I installed it and to my non surprise nothing had changed, nothing was fixed. I scratched my head for a while as I could hear the pump running but yet didn't have any fuel pressure, I removed my newly installed fuel filter to verify this and it was confirmed, pump spinning but no go go juice. I pulled the pump enough out of the tank so I could see it and had my buddy turn the key. I found that the main line coming from the pump motor was cracked spewing the gas back into the tank and not to the rail. Rock auto owned up to this and sent me a replacement pump. Another week goes by and it's time to go at it yet again.
I install the pump and find the same result, a line had opened up from the pump motor. I send the cheap-o-pump back and get a refund this time. I decide I will order a Delphi OEM pump this go round, it arrives fairly quick as I opted for expedited shipping this time. Now keep in mind that yes, I'm doing my due diligence on my end learning anything I can about this god forsaken whip that I'm ready to set fire to. In the mean time I install the original pump and continue to beat my head against the wall as this pump works, but the car idles like !@#$ after warm up and I'm getting odd codes, I even change out an O2 sensor since I'm shot gunning at this point.
What I find is there is a lack of information on this models (2004 ford explorer 4.6l NBX) fuel delivery system, I'm talking the real dirt. I am thinking now that maybe the pressure is being regulated by a FPDM (which from what I have read this model doesn't have one). I chased the cable bundle down to it entering in upwards to the rear passenger side tail light of the car. To my surprise I find it leads to an FPDM attached to the car body. If you tear apart the plastic enough you will find it is located on the rear of the passenger side, basically right behind the passenger rear taillight inside the car. I decide to do a continuity check from the each end of the plug as the module is in physically great shape and get very strange readings when I get any at all (the wire is open and on life support) I find the black with an orange stripe wire ( ground from the pump connector end) to be severely decayed just after the plug connector heading up to the taillight pass way, it took a rock or was rubbing on something, either way this was my issue the entire time.
I made new connections and the ol girl sings like a song now, I installed a new pump anyway as it has 125K on it. I now know that this module pulses ground to regulate pressure (which contradicts anything I know from the industrial world) and by me jumping the ground the pump was running 100% all the time (no bueno!!).
The point of my long winded rant is that I hope my drag out brawl with this car is able to shed some light to some other poor soul who happens upon this similar situation. Yes this model does have an FPDM and it is NOT OK to jumper the pump to ground if it opens up, check the wiring at the back of the car as explained as it is the weak link in the chain. Please learn from my mistakes!
I hope this is helpful, or if nothing else amusing at my expense. I'll post pics for those that care to take a look.
PS, my experience with rockauto was a good one, they are easy to deal with and I would recommend them.
I just finished a month long battle with a fuel delivery issue on my wife's 2004 Explorer 4.6l
She called me at work to rescue her from the side of the road. After an intense tow trip home in the snow (her first go at being towed redneck style as all my usual suspects were working) I parked the vehicle in my buddy's garage and the fun began.
Initial diagnosis: Fuel pump. I tested power from the cable to the pump to verify it had power, which it did. I ordered a $60 pump from rock auto and played the waiting game for a week. Installed the pump (which included a fancy new hole in the floor upgrade located behind the front passenger seat to avoid dropping the tank) on arrival and the ol girl barked right off. I took it for a test spin to check on my old man's place as he's on vacation and after ravaging his fridge of whatever bottom shelf liquids I could find I found the truck wouldn't start. After doing the rap on the fuel pump trick it barked off again and I headed back to my buddy's garage for what would prove to be an epic battle.
I found that I had somehow lost ground all-together. I pulled the pump and ran it directly from battery 12v and the pump worked, as did the old one. I have worked as an industrial E&I controls tech for years so basing what I know about controls in that world I spliced into the pump harness and made my own ground to the frame assuming my wire had opened up somewhere along the way. This fixed the issue. Take 2 on a test drive. I drove again to my dad's place and after letting the vehicle rest for a bit found it was dead in the water. I got the original pump and threw it in and headed back to my buddy's garage for some more fun.
I hooked up the code reader and it showed a p0191 fault (fuel rail over pressure). I ordered a new rail pressure sending unit and waited yet again. When it arrived I installed it and to my non surprise nothing had changed, nothing was fixed. I scratched my head for a while as I could hear the pump running but yet didn't have any fuel pressure, I removed my newly installed fuel filter to verify this and it was confirmed, pump spinning but no go go juice. I pulled the pump enough out of the tank so I could see it and had my buddy turn the key. I found that the main line coming from the pump motor was cracked spewing the gas back into the tank and not to the rail. Rock auto owned up to this and sent me a replacement pump. Another week goes by and it's time to go at it yet again.
I install the pump and find the same result, a line had opened up from the pump motor. I send the cheap-o-pump back and get a refund this time. I decide I will order a Delphi OEM pump this go round, it arrives fairly quick as I opted for expedited shipping this time. Now keep in mind that yes, I'm doing my due diligence on my end learning anything I can about this god forsaken whip that I'm ready to set fire to. In the mean time I install the original pump and continue to beat my head against the wall as this pump works, but the car idles like !@#$ after warm up and I'm getting odd codes, I even change out an O2 sensor since I'm shot gunning at this point.
What I find is there is a lack of information on this models (2004 ford explorer 4.6l NBX) fuel delivery system, I'm talking the real dirt. I am thinking now that maybe the pressure is being regulated by a FPDM (which from what I have read this model doesn't have one). I chased the cable bundle down to it entering in upwards to the rear passenger side tail light of the car. To my surprise I find it leads to an FPDM attached to the car body. If you tear apart the plastic enough you will find it is located on the rear of the passenger side, basically right behind the passenger rear taillight inside the car. I decide to do a continuity check from the each end of the plug as the module is in physically great shape and get very strange readings when I get any at all (the wire is open and on life support) I find the black with an orange stripe wire ( ground from the pump connector end) to be severely decayed just after the plug connector heading up to the taillight pass way, it took a rock or was rubbing on something, either way this was my issue the entire time.
I made new connections and the ol girl sings like a song now, I installed a new pump anyway as it has 125K on it. I now know that this module pulses ground to regulate pressure (which contradicts anything I know from the industrial world) and by me jumping the ground the pump was running 100% all the time (no bueno!!).
The point of my long winded rant is that I hope my drag out brawl with this car is able to shed some light to some other poor soul who happens upon this similar situation. Yes this model does have an FPDM and it is NOT OK to jumper the pump to ground if it opens up, check the wiring at the back of the car as explained as it is the weak link in the chain. Please learn from my mistakes!
I hope this is helpful, or if nothing else amusing at my expense. I'll post pics for those that care to take a look.
PS, my experience with rockauto was a good one, they are easy to deal with and I would recommend them.
