Fuel Pump (s) question
 

I have a 93 300E with the two Bosch fuel pumps connected in series. This is the same setup as many other ealry 90's W124s. Here's my questions:

1. Do both the pumps always run together or does one of the pumps turn on only when under certain load/rpm conditions?

2. Does anyone know the combined output capacity of this series confirguration ? Liters/hour? The WIS software mentions 90L/hr but I think that must be in reference to the single pump setup used earlier. The 93 500E uses the two Bosch pumps in series and would require more than 90L/hr so it must be higher.

Thanks for either answer.

pump
 

as to question #1 both run at the same time always

on the same thought process, if one is crapping out, does it stand to reason that I should replace both? I have a hard-starting problem and it sometimes won't restart. One or both is humming really loud, which I'm taking as a bad sign. I was quoted $199/pump, roundly $30 per filter, but they are not the same and $2/ for sleeves. And is this a DIY job?

$199/ pump is a very good price, since Fastlane has the bosch pumps for 266/ea. It is a fairly easy DIY job, under the rear passenger side of the car you'll find a big rectangluar plastic cover where the fuel pumps and filter reside.

There is a special test procedure which requires a special tool to determine which pump is failing, but this is only to test relatively new pumps for a defect. If you have two old tired pumps, I suggest you replace both unless you enjoy aggravation and mystery as to which pump will leave you dead in the water in rush hour traffic or in the middle of the night with limited recources.

If I'm going to all this trouble, are there any other filters or other odds and ends I should address at the same time? I want to get this sorted out once and be done with it.

I'd just change the pumps and only change the filter if it's been about 30k since the last change. I don't understand the $2.00 sleeves. What are they? If they are talking about the plastic sleeves that go on the pump, they should come with the pump, and where you live it is a good idea to make sure they install them. I'm assuming you get snow in the winter.

Be careful when you take off the inside pump, from there its a clear shot to the gas tank, and all the gas that's in it:eek:

You can buy some cool fuel hose clamps to pinch off the hoses. I have one pair that sort of looks like vice grips. I have a couple that clamp around the hose and tighten with a knob. Also I tie rags around my wrists to keep from burning the ***** out of my arm pits.

I'm not really sure what the sleeves are...I went to my parts dept with the VIN and these are the parts the M-B system spit out as being necessary for this repair. I asked the parts guy what they're for and he just shrugged. I never thought about all the gas in the tank dumping on me, guess I would have learned that little lesson the hard way if you guys hadn't pointed it out.

No reason we both need to learn that lesson the hard way:rolleyes: