E55 dual fuel pump control circuits
08-24-2015, 10:47 PM
#1
MBWorld Fanatic!
Thread Starter
Join Date: Jan 2014
Location: Republic of Texas
Posts: 3,324
Received 977 Likes
on
760 Posts
'99 and '05 E55 AMG
E55 dual fuel pump control circuits
Query: does the E55 (and other AMGs) have dual controllers for the fuel pumps? If yes, any information on the system?
My W211 E55, due to over-current draw, literally melted the fuel pump relay and the insulation on the fuel pump wires when the fuel filter clogged.
MB WIS shows dual fuel pump current draw to be 17-20 amps at idle. After diagnosing and replacing the fuel pumps and filter, I decided to assemble a test setup to measure voltage and current for both fuel pumps at regular intervals. A 15-minute test that could save me time on the side of the road on an elevated expressway during rush-hour traffic (and this happened to my wife). Probably a better tool for an aftermarket shop.
I expected both pumps to be pulling similar current. Not so. One pump is consuming approximately 180 watts of power and the other is drawing only 55 watts of power. My assumption is that the second (lower-power)pump only engages under full-throttle and full boost. I did not connect my oscilloscope but I would presume a PWM signal is applied to the pumps. If anyone knows differently, enlightenment is welcomed.
So...for now, 17.4 amps at idle. If it goes above 22 amps at idle (this is a SWAG, I'll admit), I'll replace the fuel filter. The relay that powers the two circuits to the fuel pumps is rated at 40 amps. Makes sense if the current draw at idle is 17.5 amps (13.6 +3.9), and if the current draw at full boost, full throttle, and max RPM is 27.2 amps (13.6+13.6). An engineering safety factor of 1.5 would give 27 x 1.5 = 40.5 amps which is the rating of the relay.
I assembled this using two each DROK volt/amps meters and an adaptor cable from Mercedes. Cost was $55 and a few hours of my time enjoying this.
Again, any info on dual-control circuitry for the fuel pumps would be appreciated.
My W211 E55, due to over-current draw, literally melted the fuel pump relay and the insulation on the fuel pump wires when the fuel filter clogged.
MB WIS shows dual fuel pump current draw to be 17-20 amps at idle. After diagnosing and replacing the fuel pumps and filter, I decided to assemble a test setup to measure voltage and current for both fuel pumps at regular intervals. A 15-minute test that could save me time on the side of the road on an elevated expressway during rush-hour traffic (and this happened to my wife). Probably a better tool for an aftermarket shop.
I expected both pumps to be pulling similar current. Not so. One pump is consuming approximately 180 watts of power and the other is drawing only 55 watts of power. My assumption is that the second (lower-power)pump only engages under full-throttle and full boost. I did not connect my oscilloscope but I would presume a PWM signal is applied to the pumps. If anyone knows differently, enlightenment is welcomed.
So...for now, 17.4 amps at idle. If it goes above 22 amps at idle (this is a SWAG, I'll admit), I'll replace the fuel filter. The relay that powers the two circuits to the fuel pumps is rated at 40 amps. Makes sense if the current draw at idle is 17.5 amps (13.6 +3.9), and if the current draw at full boost, full throttle, and max RPM is 27.2 amps (13.6+13.6). An engineering safety factor of 1.5 would give 27 x 1.5 = 40.5 amps which is the rating of the relay.
I assembled this using two each DROK volt/amps meters and an adaptor cable from Mercedes. Cost was $55 and a few hours of my time enjoying this.
Again, any info on dual-control circuitry for the fuel pumps would be appreciated.
Last edited by bbirdwell; 08-24-2015 at 11:36 PM.
08-25-2015, 10:27 PM
#2
MBWorld Fanatic!
Thread Starter
Join Date: Jan 2014
Location: Republic of Texas
Posts: 3,324
Received 977 Likes
on
760 Posts
'99 and '05 E55 AMG
Update on fuel pump controller modules
I still have not found the fuel pump controller modules in my '05 E55 but I did find a reference to them online. My car has the "cut lines" on the insulation over the right rear fender but nothing is mounted there. I found one picture online referencing the controller modules and relay but it is a different version of the W211 E55.
Part number is: Mercedes 035-540-01-45 Fuel Pump Driver Module. Costly little beasties at approximately $300 each.
So...it appears the relay in the trunk of my '05 E55 (build date after 06/2005) handles the current to two each fuel pump controller modules (location in my car unknown at this time).
Again, if anyone knows the location of these modules (not as shown in the picture), the information would be appreciated.
Part number is: Mercedes 035-540-01-45 Fuel Pump Driver Module. Costly little beasties at approximately $300 each.
So...it appears the relay in the trunk of my '05 E55 (build date after 06/2005) handles the current to two each fuel pump controller modules (location in my car unknown at this time).
Again, if anyone knows the location of these modules (not as shown in the picture), the information would be appreciated.
08-25-2015, 10:51 PM
#3
MBWorld Fanatic!
Join Date: Jul 2012
Location: Orbiting the planet
Posts: 4,478
Received 1,488 Likes
on
986 Posts
This place is a joke.
Saw your post in the 211 AMG section... There are no fuel pump control units, per se, they are "dumb" pumps...either on or off on the E55. There is a production year break on the E55's, but I don't have the wiring diagram in front of me, but somewhere in 2006 I believe. The early cars- 2003,4,5? ran both pumps all the time, the relay is located in the right rear trunk area, and are turned on/off or powered by the rear SAM (fuse box assembly left side of trunk.) The later E55's 2005? ,06?, ran the second pump only on "demand" as dictated by the engine control unit. If you have the factory wiring diagrams they show the month/year production break and appropriate diagrams.
