Fuel pump problem

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Joined: Mon 17 Aug, 2009 5:19 pm
Model you own: w124
Location: Wagga Wagga. NSW.

Fuel pump problem

Post by Wag230 » Fri 20 May, 2016 11:13 am

Having a fuel problem that has my mechanic stumped.
As you probably know the CLK has a saddlebag type fuel tank. Briefly what 's happening is that the fuel is not getting from the left tank to the right one.

We've run out of fuel twice when the guage shows 1/2 full.
My mechanic at first thought it was the pump. But on inspection it seems that the right side tank was just about dry and the left one was 1/2 full.

Any ideas on what's causing it and how to fix it ?
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Re: Fuel pump problem

Post by Ivanerrol » Mon 23 May, 2016 7:46 pm

Have a look through this thread of Tony's

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Tony From West Oz
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Re: Fuel pump problem

Post by Tony From West Oz » Mon 23 May, 2016 8:39 pm

My experience is with W202 C250D cars. I imagine that MB did not redesign the whole system for different models using this tank config, so this may be relevant.
You could be in luck! If the drivers side is dry, the venturi pump on that side is working properly. The passenger side being at 1/2 tank indicates that the venturi pump on that side is not working properly.
Fortunately, the venturi for the passenger side of the fuel tank is conveniently located on the fuel gauge sender and it can be removed and cleaned :dance:

If the drivers side of the tank were still 1/2 full and the passenger side empty, it is most likely that the venturi pump on that side does not work. You would then have 2 options:
1. Remove the tank and replace it (OK if you have lifetime warranty from MB, but probably wouldn't be covered any way) at a cost of around $1K or more, or
2. Add a pump to transfer fuel from the drivers side of the tank to the passenger side of the tank. I chose this method for my car.

I considered getting a tank which had been removed (because of this) and trying to locate the drivers side venturi outlet to the 'anti-splash container' and drilling a hole to allow me to blow compressed air back into the venturi, hopefully clearing the blockage. Rinse out that side of the tank and 'plastic weld' the hole closed again, but I couldn't locate a removed tank - they go straight into the skip.

I can help you drain the tank safely, using the drain valves. PM me for details.

Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

'83 W123 300D 325000km (Wife's car Josephine - sold).
'84 W123 300D replaced good OM617 912 with OM617 952 and enjoyed having good acceleration for the first time since first driving a 300D in 2002 - became engine and trans donor for 300CD Turbodiesel conversion. Now parted out.
'86 W124 300D sold (Wife's old car - sold )
'85 W123 300CD, 275 000km (Fatmobile) rebuilt turbodiesel from previous Fatmobile transplanted into 280CE (SOLD)
'99 W202 C250 Turbodiesel (my darling Wife's car - Sold)
'98 W202 C250 Turbodiesel (my car - Sold)
'06 Ssanyong Musso Crew Cab 2WD Ute (OM662 diesel and Auto Transmission)

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