What should the Fuel Rail Pressure be on OM647?

GasolineLover

New member
2005 Dodge Sprinter 5 Cylinder Mercedes Diesel...

What is the correct fuel rail pressure when climbing a hill about 2500 RPM with the accelerator pedal all the way down on the floor?

I'm getting about 19,000 PSI when the P0087 occurs (Low Fuel Rail Pressure)
 

sailquik

Well-known member
GasolineLover,
What are you using to determine that you have 19,000 PSI while driving down the road?
Why are you only running 2500 RPM.....that's about 200 RPM BELOW where the OM-647 Sprinter engine really begins to pull well.
Best pulling performance and best fuel mileage when pulling is in the 2700-3150 RPM range.
What are the sub codes associated with the P0087 DTC you are getting.
Does this throw your Sprinter into LHM?
Does it reset when you shut the engine off and restart it?
Hope this helps,
Roger
 

GasolineLover

New member
I have a scan tool that gives me fuel rail pressure (BlueDriver). I can view readings in real time and I get a file with the measured data during the event. It shows pressure on 0.1 second intervals. Pressure rises steadily as I press the pedal to the floor but tops out at about 19,600psi
I am running up a hill near my house to test the conditions causing the code to set.
I don't see any sub codes. Just P0087
I've checked the low pressure supply and it is good.
From the reading I've done, it looks like the most likely problem is that the injectors are leaking back into the return or the rail pressure solenoid is leaking back into the return. My next step was going to be to test those. But I'd like to know what pressure the fuel rail can reach when things are working properly.
 

GasolineLover

New member
Thanks for your interest.
Yes, the sprinter is going into Limp.
I'm not sure if it is coming back out of limp when I shut off and back on. But the check engine light stays on.
 

HazyOutdoor

New member
Did you ever find a fix for your issue? Im having the same exact problem. 99.2% load and 19,844psi but trips p0087. HP has been replaced, injectors are newer, leakoff test is even, new filter, new LP fuel pump in gas tank with 70psi read past filter before HP pump.
 

StevenL

New member
Did you ever find a fix for your issue? Im having the same exact problem. 99.2% load and 19,844psi but trips p0087. HP has been replaced, injectors are newer, leakoff test is even, new filter, new LP fuel pump in gas tank with 70psi read past filter before HP pump.
Under full load and full throttle mine runs around 24000 psi. Ides at just under 5k psi
 

avg_man

New member
Did you ever find a fix for your issue? Im having the same exact problem. 99.2% load and 19,844psi but trips p0087. HP has been replaced, injectors are newer, leakoff test is even, new filter, new LP fuel pump in gas tank with 70psi read past filter before HP pump.
Did you ever find a fix for your problem? I seem to have the same issue. 99.2% load and 19,850 psi when I get the P0087 code and CEL comes on.
 

Nautamaran

2004 140” HRC 2500 (Crewed)
Did you ever find a fix for your problem? I seem to have the same issue. 99.2% load and 19,850 psi when I get the P0087 code and CEL comes on.
Mine also tops at around 24,000 psi, so you’re down on pressure. The system regulates pressure by restricting the return flow out the Fuel Pressure Relief Solenoid Valve on the back end of the fuel rail, but also restricts fuel volume by cycling the Fuel Quantity Control Valve on the high pressure pump. HP fuel volume produced by the HP fuel pump is “consumed” by the:
- injector fueling events (combustion)
- injector pilot valve return flow (leak-off)
- fuel rail pressure relief solenoid valve

The pressure relief valve is controlled using a PWM signal from the ecm. The duty cycle of this signal can be viewed in Live Data on many T1N-aware scan tools… mine ranges broadly from less than 20% at idle to around 70% highway cruising. A higher value indicates “more closed” - a more restrictive relief valve setting.

If the combined volume of the fueling and leak-off is greater than the pump is producing then the system will loose pressure even with the relief valve running “maximum closed” with a 100% duty cycle signal. If that happens the ECM will set a fault code…

This can happen due to:
- excessive leak-off of injectors (also causes hard starting)
- leaking fuel rail relief solenoid valve
- fuel quantity control valve sticking closed
- worn HP fuel pump (relatively rare)

There are two leak-off test procedures described in the service manual: one for the injectors, the other for the fuel rail solenoid. Replacement of the leaky components is then required. (note that MB does not recommend servicing the OM647’s individual fuel rail components… you must swap the whole rail)

Unplugging the FQCV might diagnose a sticking valve, assuming it can open back up, though this will likely throw a separate code, which may then prevent building full power and invalidate the test.

Good luck!

-dave
 

avg_man

New member
For those who search these forums and wonder what the final resolution was, here you go.
I replaced the fuel filter twice, tapped on the bottom the tank to make sure the in-tank fuel pump was working, and performed an injector leak down test which showed barely any leak past (less than half an inch). The engine also started throwing the CEL more frequently and sometimes idling rough.

I ended up unplugging the fuel pressure sensor located at the front of the fuel rail while it was idling rough and it immediately started running fine. I ordered a new Bosch replacement sensor and everything has been good since. Runs great with no codes. Some will say you cant just replace the sensor but instead have to replace the entire fuel rail. On my OM647 I was able to get a replacement and install it myself. Amazon was cheapest, even cheaper than Roack Auto.
 

Midwestdrifter

Engineer In Residence
The rail pressure sensor can be swapped without much trouble, just make sure to follow the torque spec in the manual. The rail solenoid (back end of the fuel rail near the firewall) is much harder to replace, both due to access, and the sensitivity of the solenoid to proper torque.
 

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