P008700 Fuel presusure too low
Thread Starter
Newbie
Joined: Oct 2024
Posts: 7
Likes: 0
E220 CDI
P008700 Fuel presusure too low
Hi there,
Maybe someone can help here.
My car, Mercedes E Class, W212, 2010, E250 diesel.
Suddenly stopped on te road and I got it towed to my mechanic.
After testing with the computer, we got P008700 error, low fuel pressure in the system.
After many weeks of testing injector, high pressure fuel pump, replacing fuel filter, fuel pump and the relay beside the fuel pump, and replacing the ECU, nothing worked.
It will run for 10 to 30 min, then stops.
When we checked the coltage on the fuel pump, it was down to 3.5V
As a test, we bypass the relay the powers the fuel pump, ( the one beside it, underneath the back seat) with separate power that its only on when the ignition is on, and that got the engine running, no problem.
Has power, runs smoothly without any issues.
But I have a feeling that it could cause issues in the long run.
Question is, what exactly control the voltage going to the fuel pump?
Has anyone come accross this issue?
Regards,
Louie
Maybe someone can help here.
My car, Mercedes E Class, W212, 2010, E250 diesel.
Suddenly stopped on te road and I got it towed to my mechanic.
After testing with the computer, we got P008700 error, low fuel pressure in the system.
After many weeks of testing injector, high pressure fuel pump, replacing fuel filter, fuel pump and the relay beside the fuel pump, and replacing the ECU, nothing worked.
It will run for 10 to 30 min, then stops.
When we checked the coltage on the fuel pump, it was down to 3.5V
As a test, we bypass the relay the powers the fuel pump, ( the one beside it, underneath the back seat) with separate power that its only on when the ignition is on, and that got the engine running, no problem.
Has power, runs smoothly without any issues.
But I have a feeling that it could cause issues in the long run.
Question is, what exactly control the voltage going to the fuel pump?
Has anyone come accross this issue?
Regards,
Louie
Out Of Control!!
Joined: Apr 2019
Posts: 11,958
Likes: 6,802
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
parts canon led to pump
Hi there,
Maybe someone can help here.
My car, Mercedes E Class, W212, 2010, E250 diesel.
Suddenly stopped on te road and I got it towed to my mechanic.
After testing with the computer, we got P008700 error, low fuel pressure in the system.
After many weeks of testing injector, high pressure fuel pump, replacing fuel filter, fuel pump and the relay beside the fuel pump, and replacing the ECU, nothing worked.
It will run for 10 to 30 min, then stops.
When we checked the coltage on the fuel pump, it was down to 3.5V
As a test, we bypass the relay the powers the fuel pump, ( the one beside it, underneath the back seat) with separate power that its only on when the ignition is on, and that got the engine running, no problem.
Has power, runs smoothly without any issues.
But I have a feeling that it could cause issues in the long run.
Question is, what exactly control the voltage going to the fuel pump?
Has anyone come accross this issue?
Regards,
Louie
Maybe someone can help here.
My car, Mercedes E Class, W212, 2010, E250 diesel.
Suddenly stopped on te road and I got it towed to my mechanic.
After testing with the computer, we got P008700 error, low fuel pressure in the system.
After many weeks of testing injector, high pressure fuel pump, replacing fuel filter, fuel pump and the relay beside the fuel pump, and replacing the ECU, nothing worked.
It will run for 10 to 30 min, then stops.
When we checked the coltage on the fuel pump, it was down to 3.5V
As a test, we bypass the relay the powers the fuel pump, ( the one beside it, underneath the back seat) with separate power that its only on when the ignition is on, and that got the engine running, no problem.
Has power, runs smoothly without any issues.
But I have a feeling that it could cause issues in the long run.
Question is, what exactly control the voltage going to the fuel pump?
Has anyone come accross this issue?
Regards,
Louie
AtoZ got replaced without improvement until the tank pump 03.5V got directly connected then everything works.
What low and high pressures are available?
What's the mileage?
Any other chassis faults that impact CAN-C?
I wonder if tank pump uses a 3-phase controller like GDI low-pressure feed. Is sensor shot ?
Last edited by CaliBenzDriver; Oct 11, 2024 at 03:54 PM.
Out Of Control!!
Joined: Apr 2019
Posts: 11,958
Likes: 6,802
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
This confirms the low pressure is from a 3xPhase AC pump...
I really don't get how it can run on 12Volts DC??
Mercedes fuel Pumps were legendary for burnt connections from high currents - Double check for good measure in addition to priors.
I really don't get how it can run on 12Volts DC??
Mercedes fuel Pumps were legendary for burnt connections from high currents - Double check for good measure in addition to priors.
Thread Starter
Newbie
Joined: Oct 2024
Posts: 7
Likes: 0
E220 CDI
You have a Direct Injected diesel with fault for low fuel pressure.
AtoZ got replaced without improvement until the tank pump 03.5V got directly connected then everything works.
What low and high pressures are available?
What's the mileage?
Any other chassis faults that impact CAN-C?
I wonder if tank pump uses a 3-phase controller like GDI low-pressure feed. Is sensor shot ?
AtoZ got replaced without improvement until the tank pump 03.5V got directly connected then everything works.
What low and high pressures are available?
What's the mileage?
Any other chassis faults that impact CAN-C?
I wonder if tank pump uses a 3-phase controller like GDI low-pressure feed. Is sensor shot ?
direct wire to the fuel pump worked but I have a feeling it’s not the right thing
Thread Starter
Newbie
Joined: Oct 2024
Posts: 7
Likes: 0
E220 CDI
look to MB wiring diagram PE47.40P-2101DAC the 651.911 fuel pump is controlled by N118 fuel pump control mod---first remove all the BS wires you attached then check B4/7 fuel pressure switch then front SAM fuse f34 and rear SAM fuse f42 if ok then you have a faulty N118 fuel pump control mod(under R rear seat)----fyi there is no relay in the 651 fuel system----forget all the other HS
That's the feed I bypassed with direct current.
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Out Of Control!!
Joined: Apr 2019
Posts: 11,958
Likes: 6,802
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
hooking up an AC pump on DC is not the way forward.
Hook up a compatible scanner to troubleshoot what's wrong will help you stop replacing good parts for no progress.
Let us know when you're ready
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From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
This engine , its fuel pump at the tank is not 3 phase unit as per the diagram PE47.40P-2101DAC
It is a 2 wire pump. So traditional simple pump, with speed control PWM probably.
Attached N118 wiring
Need a proper scanner to see what is the fuel pressure ( B4/7 sensor ) as seen by N118.
The amperage and voltage of duty cycle of the fuel pump as read by N118 should be available if using Xentry .
Sorry, me have no experience with diesel fuel pump and not a 3-phase pump.
It is a 2 wire pump. So traditional simple pump, with speed control PWM probably.
Attached N118 wiring
Need a proper scanner to see what is the fuel pressure ( B4/7 sensor ) as seen by N118.
The amperage and voltage of duty cycle of the fuel pump as read by N118 should be available if using Xentry .
Sorry, me have no experience with diesel fuel pump and not a 3-phase pump.
Last edited by S-Prihadi; Oct 12, 2024 at 11:41 AM.
Thread Starter
Newbie
Joined: Oct 2024
Posts: 7
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E220 CDI
There is something very wrong with you or your mechanics thinking----you used xentry to get the fault----all you had to do is double click the fault and you would see three very simple electrical tests to locate the faulty part--is it the sensor, fuses, fuel pump control module or the pump----what did you do!!!!
And I got desperate, after waitting for 4 months, and when I got a chance to get it to work, I took it, as I need to do the NCT (4 months waitting list) and it passed with flying colors
I know is not the right thing to do, the reason I am here asking experts, because I want to get to the bottom of it.
As far as I know, the mechanic changed the fuel rail line and the sensor.
