Low Fuel Pressure Check Engine
Thread Starter
Junior Member
Joined: Mar 2023
Posts: 41
Likes: 8
GL63
Low Fuel Pressure Check Engine
My 2014 GL G3 AMG has had a check engine light come and go and I was ignoring it.
Initially it was upon hard acceleration and Autozone checked the code for me....something about too much boost "turbo".
Apologies, I don't have the code that it was for the turbo...and this thread is about a different matter.
That turbo matter has somehow cleared itself up (is gone) no code...but I suspected a "new" issue was present because upon HARD acceleration (passing a semi on freeway or flooring the accelerator) I have noticed the check engine light come on immediately after a "bump sensation" at WOT at which time seemingly the engine computer says "ah ah NO" and it's like the engine computer cuts off accelerator or derates (to protect the engine possibly) won't complete a WOT pull.
Anyway, with an immediate code set at that instant (of doing a WOT pull) a few days later the check engine light goes out but go do another HARD pull turns the check engine light right back on... so I went to autozone and it read P0087 LOW FUEL PRESSURE. No other codes present (initially).
The car was sitting for two weeks and upon a cold start the check engine light came on this time with a P0030 engine misfire accompanied by the LOW FUEL PRESSURE CODE.
My question on a 140 000 mile engine is should I suspect a bad fuel pump (that it's failing on low side) or is it wasteful to just "assume" and swap out a fuel pump (without doing any) testing of fuel pressure or potential data collection?
- I have zero data logging tools mind you....
I watched a couple videos from some Italian fellow linked to a thread someone posted on an ML63 with same issue and his fix was drop fuel tank and replace the fuel pump....this of course after he diagnosed it.
Sorry cannot make it to dealer. Car drives fine if you stay out of the WOT accelerator function...
NO HARD PULLS.
Thanks
Initially it was upon hard acceleration and Autozone checked the code for me....something about too much boost "turbo".
Apologies, I don't have the code that it was for the turbo...and this thread is about a different matter.
That turbo matter has somehow cleared itself up (is gone) no code...but I suspected a "new" issue was present because upon HARD acceleration (passing a semi on freeway or flooring the accelerator) I have noticed the check engine light come on immediately after a "bump sensation" at WOT at which time seemingly the engine computer says "ah ah NO" and it's like the engine computer cuts off accelerator or derates (to protect the engine possibly) won't complete a WOT pull.
Anyway, with an immediate code set at that instant (of doing a WOT pull) a few days later the check engine light goes out but go do another HARD pull turns the check engine light right back on... so I went to autozone and it read P0087 LOW FUEL PRESSURE. No other codes present (initially).
The car was sitting for two weeks and upon a cold start the check engine light came on this time with a P0030 engine misfire accompanied by the LOW FUEL PRESSURE CODE.
My question on a 140 000 mile engine is should I suspect a bad fuel pump (that it's failing on low side) or is it wasteful to just "assume" and swap out a fuel pump (without doing any) testing of fuel pressure or potential data collection?
- I have zero data logging tools mind you....
I watched a couple videos from some Italian fellow linked to a thread someone posted on an ML63 with same issue and his fix was drop fuel tank and replace the fuel pump....this of course after he diagnosed it.
Sorry cannot make it to dealer. Car drives fine if you stay out of the WOT accelerator function...
NO HARD PULLS.
Thanks
Last edited by MB18436572; Aug 19, 2025 at 02:09 PM.
Thread Starter
Junior Member
Joined: Mar 2023
Posts: 41
Likes: 8
GL63
Update:
I spoke to the dealership and they were very nice and encouraged me to come in.
I am thinking however to spend the money and buy a professional automotive scanner and subscriptions…
I am thinking that maybe I will be able to drill down into the fuel system computer and verify more than the standalone P00087 code
I spoke to the dealership and they were very nice and encouraged me to come in.
I am thinking however to spend the money and buy a professional automotive scanner and subscriptions…
I am thinking that maybe I will be able to drill down into the fuel system computer and verify more than the standalone P00087 code
Super Member
Joined: Jun 2025
Posts: 784
Likes: 250
From: USA
Based on your symptoms, it's almost certainly the low-pressure fuel pump. The P0087 code and the engine cutting out at WOT are classic signs. At 140k miles, replacing it is not a wasteful guess. That is the most common fix for this exact issue.
Thread Starter
Junior Member
Joined: Mar 2023
Posts: 41
Likes: 8
GL63
Update:
this is/was most definitely the Low pressure pump going out. I hooked up a gauge and have less than 5.5 bar at idle and noteworthy the low pressure pump failing is contageous causing damage to downstream systems subsequent attempts at WOT pulls caused damage to the high pressure fuel pump(s). Replacing low pressure pump and both high pressure pumps.
M157
this is/was most definitely the Low pressure pump going out. I hooked up a gauge and have less than 5.5 bar at idle and noteworthy the low pressure pump failing is contageous causing damage to downstream systems subsequent attempts at WOT pulls caused damage to the high pressure fuel pump(s). Replacing low pressure pump and both high pressure pumps.
M157
