I went out this morning to start my 1989 300TE and I hear a sound kind of like air being released from a tire when or air compressor when you push on the valve. I looked under the car and sure enough there was a puddle of gasoline there, so I pull the cover off and had an assistant give the key a turn and from the end of the fuel pump (facing the front of the car) there where 4 streams of fuel shooting out.

I was wondering what was causing this and can the pump be rebuilt?

I also see on Pelican Parts that it says there are two, I only see the one...So where is the 2nd one located?

There is also a choice of Bosch or Walbro. Is one of these preferred over the other?

The 300 TE (124.090) always have two fuel pumps.

The second is mounted left to right against the fuel tank under a black cover. Just follow the fuel lines and you'll see it.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Fuel pumps rarely spring a leak like that. I am all about buying new but in this case is pick up a set on eBay or something. Buy All new rubber hoses and copper washers and you will be good as new.

Down there you should see two smaller cylinders, (fuel pumps), and a large one which would be the fuel filter.

There was a model that had only one fuel pump but I think it was the 260e or something. Snap a picture if you can, that will remove all doubt.

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

Only the 260 E (124.026) and 300 E (124.030) produced before 11/1986 (not 300 TE) had the one fuel pump.

The fuel pumps are in series to produce enough pressure to run CIS injection. Many brands of cars use one pump, the only reasons I can think of to use two is noise / pump life and the ever so slight chance of limp home at half fuel pressure.

If you live in a salt area, the metal / rubber tube between the two pumps might be leaking.

Fuel spray under pressure is way more dangerous than a drip, keep heat / sparks / bare trouble lights away.

The use of the second pump is solely to prevent the formation of vapor bubbles. It does not provide extra volume. However if the first pump's performance declines, I am sure it helps provide a buffer for longevity. But that is not the designed thought.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

The wagons are weird in that one pump is rear of the subframe near by the diff in the middle of the car and the other is under the cover on the right rear along with the filter. The pumps usually leak at the check valve fittings so I would make sure that there isn't a situation where tightening the fittings would resolve the problem. To tighten the check valve fittings you need to slack off the acorn nut sealing the banjo fitting before tightening the check valve fitting into the pump body. Counter hold the check valve, not the pump body, while tightening the acorn nut.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

Formation of bubbles from where?

The series pump setup increases pressure due to 2 stages. If one motor was strong enough, both pumping elements could be driven by the same motor giving the same effect. Pressure is only built when the outlet is restricted and the resulting increase in pressure is shared between the two pumps. ( Both pumps have the same part number. )

Gravity >> pump 1 + 50 PSI >> 50 PSI >> pump 2 + 50 PSI = 100 PSI

Don't know. Its in the factory service manual. MB sure didn't go through the extra work and updates to add a secondary fuel pump without reason.

It may only affect a minority of vehicles under certain circumstances -- but that is why our vehicles are quality.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Not worth the trouble, the pumps are critical to the car operating. Just get a set of new ones and then you don't have to worry about them again for 15-20 years. I replaced ALL of the components under my 420 a couple years ago, lines, pumps, filter, bracket....0 issues, and smooth and quiet. Buying a used pump on ebay means you are possibly getting another 20 year old pump with hundreds or thousands of hours of use on it.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I havent pressured checked an MB yet but in a Volvo, the 1st pump goes to about 40psi while the 2nd pump takes the fuel to the needed 75psi.

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1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

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