been having problem with my 2008 crd srt design
engine management light comes on also etc light ...car was going into limp mode used code reader and code p0088 high fuel rail pressure fault came up
cleared codes comes back again and car shuts down ..when i check fuel rail pressure it goes all the way up to 47000..anyone any ideas or know what the fuell rail pressure should run at.or what part could be faulty..is there a regulator or solenoid .........:17:
Fuel pressure will typically be just below 4000 psi at idle and about 23000 psi under max acceleration.
Could be:
Fuel Pressure sensor giving wrong info to ECU
Contaminated Fuel
Air in Fuel
HP Fuel Pump
Fuel Pressure Quantity Solenoid
Fuel Pressure Solenoid
Its a long list and a case of deciding which way to go.
If you have a code reader or access to a code reader you could start by reading the fuel pressure when the ignition is set to "Run" but without starting the engine. This will allow the electric pump to prime the system before the mechanical pump runs. The code reader would then be able to read the fuel pump pressure which should be around 150psi (or thereabouts, not critical). This would basically prove the Fuel pressure sensor is not giving out a permanently high output.
Would probably be worth checking for chaffed wiring in the engine compartment in case the fuel pressure sensor wires are chaffed and giving a permanently high output. 43000 is very high though so I would suspect chaffed wires or a faulty pressure sensor.
Just read that you have a code reader.
Connect it up and read pressure without starting engine. Should be low (about 150psi)
thanks ..tried conecting code reader when ign on gives a reading of 5710kpa or 828 psi so it looks like its giving a high reading before mechanical pump kicks in ...any idea where the sensor is there seems to be a sensor on each fuel rail front of rhs and rear of lhs looking from front of car ..please can anyone help...does anyone even know what mercedes engine this is so i can source parts
The Fuel Pressure Sensor is on the RH fuel rail at the end nearest the windscreen (RH when sitting in the car).
If you have a voltmeter you could check that the 5Volt supply on pin 3 is actually 5V and not something greater.
Also check pin 1 has good continuity to chassis or has zero volts on it.
See drawings attached.
You have to be very careful working on the fuel system on modern diesels the pressure can get extremely high.
Engine is an OM642 but not sure which version.
I would not be certain its a faulty sensor though because the reading has not stayed at the very highest value measured. The fuel pressure solenoid would be worth a check. Ideally the fitting of a temporaray mechanical pressure guage would confirm if the pressure sensor is faulty or not.
thanks jack...certainly will try that ..one last thing i tried..i unplugged the fuel pressure sensor this gave a reading of 33000 kpa when unplugged took the car for a drive and drives fine not going into limp or shutdown and shows no fault codes......any further thoughts would much appreciated
thanks jack...certainly will try that ..one last thing i tried..i unplugged the fuel pressure sensor this gave a reading of 33000 kpa when unplugged took the car for a drive and drives fine not going into limp or shutdown and shows no fault codes......any further thoughts would much appreciated
You could have left the code reader plugged in to monitor the fuel rail pressure while driving.
Have someone in the passenger seat looking at the reader and shout out out the pressure. Drive at a steady speed and have them write down the pressure. Accelerate hard and write down the pressure. (This is assuming your reader hasn't the capability to draw a graph)
As said before should be about 4000psi at idle and 23000psi accelerating hard.
There is an APP for Android phones called Torquepro but you also need an ELM ???? electronic device to plug into your OBD socket to get the readings to the phone. This app is very good and gives you graphing capabilities.
I would definitely check wiring for chaffing as well though. But to get your problem the 5V supply would have to short to the sensor wire on Pin2 which is unlikely. The shorts on 300C's are usually to chassis.
thanks again jack im going to try fuell pressure sensor and fuel pressure solenoid ...just waiting for delivery ...thanks for your help will let you know how i get on
You do need some means of monitoring the fuel pressure and analyzing the results.
Problem can sometimes be caused by:
1) Air in the fuel system causing spikes in pressure
2) Fuel Pressure sensor
3) Fuel injector or injectors
4) Fuel pressure solenoid
5) Fuel Pump
6) Fuel system contamination causing spikes in pressure.
You should also checked for chaffed wires round engine bay, especially at the RHJ rear of engine when viewed from front: around the air conditioning pipes.
BUT you must have some means of measuring the pressure. Even if its just an OBD reader.
Its difficult to tell, and I am no expert, but the video does not help much because the accelerator is being pressed too often and it doesn't give a chance to see how stable the pressure control is.
I assume there are no other error codes ?
The ECM sends a signal to the pressure control system and tells the system exactly what pressure to deliver. If the pressure spikes by more than about 7Kpa it will set the code P0088 which you have.
The pressure range on your video looks about right so it is just the specific pressure that is not being regulated accurately enough for some reason. Its difficult to check the control on the video because the accelerator is being operated too much.
It could possibly end up being the:
Fuel Pressure Solenoid or the
Fuel Quantity solenoid.
These are usually checked by replacing them as they are difficult to prove.
If possible you could check the fuel pressure again under various accelerator positions, but maintain the accelerator steady at a few different positions so you can see exactly how bad the pressure control is.
I think you will probably just have to swap the Fuel pressure Solenoid or Fuel Quantity solenoid and see how it goes.
I assume you have done the basic check of changing the fuel filter and cleaning out the housing ?
It doesnt surprise me that you have also had the low error code up also. As I said before it is just bad control for some reason.
Poss Fuel Quantity Solenoid or Fuel Pressure solenoid. Just because you have 12V supply doesnt mean they cant be faulty. i.e. Passing Fuel when they should be shut off, or not passing enough fuel.
A dealer would just swap these one at a time and work on the process of elimination. No easy checks can be made to find out if they are working OK. Can only be proved to work if the car runs OK as far as I'm aware.
I assume you have checked the wiring loom for chaffing as mentioned before.
The cable loom does rub through on these cars and cause many false error codes.
They rub through in the area of the Air Con pipes, twist the loom around and check for signs of rubbing or poss bare wires.
Hope you get it sorted soon. It is access to replacement spares to try that is the biggest problem so you can swap and retry
RH rear of engine when stood at the front looking at the engine.
If the wires are OK and it was my car I would go for the Fuel Quantity Solenoid first, but this is only a guess. But this solenoid controls the fuel flow to the HP fuel pump.
If the wires are OK and it was my car I would go for the Fuel Quantity Solenoid first, but this is only a guess. But this solenoid controls the fuel flow to the HP fuel pump.
hi, i have no problem with low pressure any more few days driving and no problems at all drive as should but still have problem with fire up the engine at first time need turn the engine few seconds some times repeat few times, any suggestions ?
Even with the current ambient air temperature the glow plugs should probably come on for a few seconds.
If it is only a problem the first time you try and start it on a cool morning and it starts OK if you shut it down and try it a few minutes later you could have glow plug, or glow plug circuit problems.
As said before not necessarily the glow plugs themselves but could be the glow plug circuit (relays etc.)
But I don't fully understand what you mean. Are you saying it is bad to start in a morning and then is worse once it warms up and the coolant temperature is 89 Degrees ? (I assume you mean degrees C)
Once the coolant temperature is up to 40 Deg C there probably wouldn't be any need for the glow plugs. Especially with ambient temperatures at the moment.
Glow plugs operate for a certain length of time dependent upon, Air Temperature/Coolant Temperature/Battery Voltage.
See attachment for Glow Plug operating times dependent upon coolant temperature.
Yes I agree could be a Crank Sensor especially if problems on hot start. But it does appear as though it does eventually start OK.
I cant quite understand the symptoms poster is describing.