Fuel pump function - Benzworld.org - Mercedes-Benz Discussion Forum

Naj · 11-19-2009, 07:18 PM

Hi,i know w124 300e have 2 fuel pumps,but i would like to know why 2 not only 1?And how do these 2 function togather?Thank u

i6h000 · 11-20-2009, 06:56 AM

I've asked this ques myself w/ no replies. I do know they are set up for parallel operation (fuel passes through one then is directed to the other). Surely mercedes could of designed a single pump for the proper pressure/capacity needed but I believe by using two pumps it is designed to be a fail safe deal that if one fails, the other will be sufficient to start and operate the car (limited speed and power of course) to get you safely home or to the nearest service facility. The chance of both pumps failing at the same time (unless there is an electrical issue) is pretty unlikely. There is really no other logical reason for two pumps. This would be easy to test by disconnecting the power to one pump and seeing if the car will start and operate. I'm sure someone has tried this before.

Elk of the Month · 11-20-2009, 07:36 AM

I believe the two pumps serve different purposes, while still functioning together. One establishes fuel pressure, and the other maintains it. This kind of system was used on even older Mercedes as well.

No need to test out whether or not the car will run with only one pump though, its the way the car was designed. Engineers didn't waste hours configuring the W124 fuel system only have it deemed unnecessary and removed.

Naj · 11-20-2009, 01:55 PM

Thank u for replying,can u check my other topic and tell me what u think about that?it is 300e hesitation.

maliyer35 · 02-17-2010, 09:26 AM

hi ı have 86 260E W124 mercedes and ı have problem with fuel pump. but ı dont find where the fuel pump is?? I'm going to be crazy. if one of the man say me where the fuel pump is I will be very very grateful. I'm waiting your helps...

**Jayare** · 02-17-2010, 11:09 AM

Quote:

Originally Posted by maliyer35

hi ı have 86 260E W124 mercedes and ı have problem with fuel pump. but ı dont find where the fuel pump is?? I'm going to be crazy. if one of the man say me where the fuel pump is I will be very very grateful. I'm waiting your helps...

Beneath the car, under the right rear passenger seat, you will find a black plastic shield. Remove the four plastic nuts that secure the shield, drop the shield and find the fuel pumps and fuel filter.

Take just a few minutes and please complete your profile. It helps all of us, better help you. Welcome and

Good Luck,

Jayare