Fuel rail pressure , front sensor or rear ?

One call a/c

New member
Hello everyone.
Have had some issues with a fuel rail pressure codes for a few months. Key cycles reset and sometimes it runs perfect, others little acceleration and 2800 rpm max with pedal to the floor. I have an autel 802 which seems to cover a lot of the complex modules. So today I was monitoring the live data of the fuel rail pressure and I witnessed the pressure go from 18,000 psi to 0.0 psi. Then after a few seconds it goes back to normal. My question is what sensor is actually showing the rail pressure, the one on the front of the rail or the solenoid on the back ??


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NelsonSprinter

Former Nelson BC Sprinter
To my knowledge the front is the pressure sensor, the rear is the pressure control regulator/solenoid
 

random

05 140" SHC 2500 Cargo
As you know i have been watching my rail pressures also. As far as I know, it should not drop to 0, the van would do far more than a mild LHM, it would totally quit. In fact, to drop to zero would take several minutes of engine being off. So this makes me suspect your fuel pressure sensor(front of rail). Get more advice before you spend the money, but that my 2 cents.
 

One call a/c

New member
Thanks random. I plan on it. Don't wanna throw parts at it. Especially expensive ones at that. I looked at the harness to see if there were any cuts or wear but couldn't see any. Could be the sensor. But seems unlikely though. I'll just keep plugging.


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One call a/c

New member
In the third picture where it just shows the four sensors being monitored the FRP is around 45,___ psi at that rpm(idle) and it's showing 7 +. Now after I turn the van off and start right back up it goes back to the 45,000 psi at idle. I'm thinking the sensor is toast.


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One call a/c

New member
Trying to upload the video with the graph but it's not letting me saying upload failed network error šŸ˜’


Howboutcha-
 

One call a/c

New member
Ok. I had the scanner in hand while checking out the sensor/ plug / wiring ect. I started the van and the fuel rail pressure was normal to start. I started wiggling the plug and wiring nothing changed. So I unplugged the sensor on front of rail and the engine rpm spiked for a sec and went back down. The scanner showed 21,--- psl frozen on the graph. So I plugged it back in and the graph started to show the psi reading again BUT now the reading is HIGHER like when I start having issues while driving. Basically when my problem arises with the slow acceleration 2800 RPM Max the PSI of the fuel rail is normally higher on the scanner then normal. So when I unplugged the sensor, and plugged it back in the reading was higher than normal. My question is where does the fuel rail sensor on the front of the rail get its power from. Is there power at this sensor at all? I'm trying to determine if the sensor itself is the problem or if it's loosing power/connectivity from somewhere ???
 

Aqua Puttana

Poly - Thread Finder
5 vdc

215CommonPointFaultDiagnosis.jpg

229CommonPointFaultDiagnosisNote.jpg

vic
 

One call a/c

New member
Does anybody know if the fuel rail sensor is measured differently than the fuel rail solenoid I get psi on the fuel rail pressure sensor and I'm not sure if that fuel rail solenoid is measured and bar any clues or ideas?

Today I plug the scanner and when first starting up the sprinter taking it for a drive I had immediate PSI zero out intermittently got to my destination about 30 minutes away turned it off another 15 minutes 20 minutes started it back up everything's fine no problems. Turned it off turn it back on no problems everything's fine beginning to wonder if the sensor issue is when happening when it's cold rather than warm? at a loss

I'm wondering if a sensor could fail like that intermittently and then cycle the key and it be fine or if there's an ECM problem?

Or could another sensor cause me to get a zero psi reading it doesn't seem likely the scanner live data is measuring or at least monitoring the PSI output of that sensor and four to go to zero that quick and then go back to normal its boggling


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random

05 140" SHC 2500 Cargo
Well I think it is the solenoid. I have another one on the way now. Did you test yours?
 

One call a/c

New member
Yeah. Nothing got by it on the leak-off test. Injectors are good also. There's something going on with the rail sensor on the front or the ecm.


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One call a/c

New member
When it's acting out , I can get the live data to show it zeroing out as im driving and sometimes when I press the pedal fast. Then I can shut her down , start back up and everything is perfect. No crazy live data reading, great power , no problems. I am suspicious if this problem is happening after the van is sitting for a while either overnight or for a good amount of time I'm going to keep an eye on that before I order a rail sensor


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One call a/c

New member
random, have you monitored your rail pressure while driving? What kind of readings are you getting ?


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random

05 140" SHC 2500 Cargo
random, have you monitored your rail pressure while driving? What kind of readings are you getting ?


Howboutcha-
I get about 350 or so bar at idle then up to 1350 or so before it goes into its LHM thingy.
You should never see a 0 reading like you got.
 

One call a/c

New member
Yeah. I never see zero when in the mode your seeing bar. That is normal. It's in the obdll mode then live data is when I see the psi reading of the rail. That's when I see it go to zero and kick me into LHM or fuel related LHM. I can clear the code while driving and I get my power back unless it sees zero again. I did that today while taking an hour drive to a job.


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