280s fuel pump

1965 - 1972: 250S, 250SE, 300SEb, 280S, 280SE, 280SEL, 280SE 3.5, 280SEL 3.5, 280SE 4.5, 280SEL 4.5, 300SEL, 300SEL 6.3, 300SEL 3.5, 300SEL 4.5
Post Reply
mercjerk
Dernburg Wagon
Posts: 8
Joined: Sat 13 Aug, 2016 3:42 pm
Model you own: w108
Location: melb

280s fuel pump

Post by mercjerk » Thu 25 Jan, 2018 5:51 pm

hi . can i get a kit to repair my mechanical fuel pump m130 zenith carbys.. its leaking fuel after storage of 6 months
diaphram i suspect

User avatar
Bartman4800
300 SLR
Posts: 1905
Joined: Fri 10 Oct, 2008 12:10 am
Model you own: w111
Location: Perth WA

Re: 280s fuel pump

Post by Bartman4800 » Thu 25 Jan, 2018 6:30 pm

Send us a picture of the pump please.

Is this about the fuel pump or the acceleration pump on the carbie?

Some of the later pumps are replacement only. But the earlier ones can be rebuilt.

Also, be so kind to add your location in your profile, so local people can help you.

First port of call is the forum sponsor (MBspares in Canberra)
Then there is Ruddies in Berlin, Germany, who can get a kit for just about any (older) mechanical fuel pump in existence....


Regards, Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

mercjerk
Dernburg Wagon
Posts: 8
Joined: Sat 13 Aug, 2016 3:42 pm
Model you own: w108
Location: melb

Re: 280s fuel pump

Post by mercjerk » Fri 26 Jan, 2018 11:16 am

IMG_20180126_101402494.jpg
IMG_20180126_101337736.jpg
thanks for your advise
You do not have the required permissions to view the files attached to this post.

User avatar
Bartman4800
300 SLR
Posts: 1905
Joined: Fri 10 Oct, 2008 12:10 am
Model you own: w111
Location: Perth WA

Re: 280s fuel pump

Post by Bartman4800 » Mon 29 Jan, 2018 12:09 pm

Yep,

That one is fully rebuildable, have done one myself.

See earlier reply to get spare parts.

If the diaphragm fails it might dump fuel into your sump oil.

Check the valves too, they are bakelite circles with a little spring behind.


Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

User avatar
VFRBoy
B Class
Posts: 22
Joined: Fri 18 Mar, 2016 2:48 pm
Model you own: w108
Location: Watsonia Vic

Re: 280s fuel pump

Post by VFRBoy » Wed 31 Jan, 2018 2:18 pm

In a related area, after sitting for a few days I seem not to have any fuel in the float bowl. Makes starting difficult, and I fret about flattening the battery while cranking over and over waiting for it to fire..

Is there a drain-back valve or similar to keep it there? Does pumping the accelerator before starting draw fuel from the tank or does the fuel pump need to turn over while cranking to draw fuel up to the carbies?

Or does an electric fuel pump in the tank solve this?
1966 W108 250S
4-speed floorshift

Carn the Dees...

User avatar
Bartman4800
300 SLR
Posts: 1905
Joined: Fri 10 Oct, 2008 12:10 am
Model you own: w111
Location: Perth WA

Re: 280s fuel pump

Post by Bartman4800 » Wed 31 Jan, 2018 2:50 pm

Hi,

Pumping the accelerator does nothing if your fuel bowls are empty.

I don't have these carbs, but fuel evaporation from the bowls is a known thing on Solex carbs.
It could be drain back, that is easy to check - run your engine then undo the fuel hose between pump and carbs.
Check again after a week.

The engine needs to crank over to operate the pump, which works from a cam on the distributor shaft.

You can go with an electric pump, but I would not run both if I was you.
Either take out the mechanical pump and run an electric one, or just leave it be and make sure you have a fully operational pump.
Don't discard old technology because it just has not been maintained...


Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

User avatar
VFRBoy
B Class
Posts: 22
Joined: Fri 18 Mar, 2016 2:48 pm
Model you own: w108
Location: Watsonia Vic

Re: 280s fuel pump

Post by VFRBoy » Wed 31 Jan, 2018 3:45 pm

Thanks. I figured that the accelerator pump would only be effective it it has something to, well, pump..

Do you know if there is a non-return valve or similar that may have failed? Or can be retro-fitted inline?

Common in diesels of course, but what about ours?
https://www.onlineautoparts.com.au/prod ... /ZPN-03897
1966 W108 250S
4-speed floorshift

Carn the Dees...

User avatar
Bartman4800
300 SLR
Posts: 1905
Joined: Fri 10 Oct, 2008 12:10 am
Model you own: w111
Location: Perth WA

Re: 280s fuel pump

Post by Bartman4800 » Wed 31 Jan, 2018 5:11 pm

There is a non-return valve in the fuel pump, but no separate valve.
However, if the fuel in the line bleeds down because of a leaking pump valve, it cannot suck fuel out of the carburetor bowl because of the air gap above the float level.

Rebuild your pump, make sure the valves work before you start adding parts.

Like I said, the Mercedes Engineers knew what they were doing.

Also, make sure your fuel lines are not full of crap, and the tank filter is not blocked.
There are rubber joiners under the floor in the middle of the car. Make sure all rubber hoses are crack free. Your pump may be sucking air...

Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

User avatar
VFRBoy
B Class
Posts: 22
Joined: Fri 18 Mar, 2016 2:48 pm
Model you own: w108
Location: Watsonia Vic

Re: 280s fuel pump

Post by VFRBoy » Thu 01 Feb, 2018 10:28 am

OK so before starting it this morning I checked the inline fuel filter - it's just before the fuel pump and was 3/4 full. Fuel lines all appeared secure and no leaks apparent.

I pumped the throttle lever on the carbs 15 times and checked the fuel lines again - fuel filter actually appears full now.

Then hopped in to start it. Fired immediately, ran fine thereafter. Possibly fuel in the lines was drawn through by pumping the accelerator pumps?

If there was going to be a problem it would have been today as the car has sat for 10 days, including through 4 days of 40+ heatwave.

Anyways, this will do for now!
1966 W108 250S
4-speed floorshift

Carn the Dees...

Post Reply

Return to “W108/109”