Fuel Pump Options

1961-1968: a.k.a "Finnie" or "Heckflosse" models
190, 190D, 200, 200D, 220b, 220Sb, 220SEb, 230, 230S, 250SE coupe, 280SE coupe, 280SE 3.5 coupe, 220SEb cabrio., 250SE conv., 280SE cabrio., 280SE 3.5 Cabrio., 300SE, 300SE coupe, 300SE conv., 300SEL
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harryskater_220
250s
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Joined: Mon 11 Feb, 2013 7:46 pm
Model you own: w111

Fuel Pump Options

Post by harryskater_220 » Fri 02 Jan, 2015 6:19 am

While I'm on with my resto I'm wondering if there's a general rule of thumb to determine if the diaphragm in my mechanical fuel pump (APG stamped on the side) should be replaced. The diaphragm part all looks intact and is softer than the gaskety part which gets screwed down but does feel a little tough. I don't have a new one to compare with and I know this has been unused for many years as it came from the donor car.

I'm wondering what you lot think of swapping the entire pump out for a style I've seen used on the pontons with the priming lever (would this be any more beneficial than the original?) or, is it best to just give it an overhaul with new diaphragm and seals etc- if so where do I find the correct kit for my pump? I've seen SLS mentioned but it looks like it's for a different unit.

At this stage I'd rather change old parts out than keep something in which is likely to give up a short distance down the road.

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Bartman4800
300 SLR
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Location: Perth WA

Re: Fuel Pump Options

Post by Bartman4800 » Fri 02 Jan, 2015 12:46 pm

I ordered a new original pump for my maroon finnie (from memory it was 70 euros) from Ruddies:

http://www.ruddies-berlin.de/index2.html

This is the one without the lever you are talking about.

Kermit (my new green purchase) has a pump with a lever, but I haven't had to use that yet.
I guess if you leave the car a long time you can use the lever to prime your carbs before you flatten the battery...


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)

CraigB
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Re: Fuel Pump Options

Post by CraigB » Fri 02 Jan, 2015 3:09 pm

If your going to use the car I would be tempted to hide an electric pump somewhere! Just had a bad day yesterday down on our scrub block watering 250 young trees with a fire unit on the back of my series 2a landrover which has a mechanical pump, with a lever. But being a hot day, every time I stopped the car and fuel not pumped through to cool the pump, the fuel would vaporise and the only way to get it started again was to pour water over the pump and then work the lever until fuel appeared in the filter. Then it would start and run fine until I stopped again. Not normally a problem but a real PITA yesterday. Not something I would want to deal with if I was actually using it in a fire situation so next time I go down will take a little facet pump or something and a bit of wire to connect into an ignition 12v feed. And that is a brand new oem out of the box pump fitted about 12 months ago. There is an insulating block between pump and engine, but it gets bloody hot down there on a hot day.

Just thought I would plant the thought though.
Craig Baulderstone
Lurch
280s's
280SE3.5
280SL
350SL
500SEC's
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Bartman4800
300 SLR
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Joined: Fri 10 Oct, 2008 12:10 am
Model you own: w111
Location: Perth WA

Re: Fuel Pump Options

Post by Bartman4800 » Fri 02 Jan, 2015 3:16 pm

Isn't that why there is a fuel return line back to tank on the carburized finnies (and others)

That should take care of a vapour lock, or not?

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)

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harryskater_220
250s
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Joined: Mon 11 Feb, 2013 7:46 pm
Model you own: w111

Re: Fuel Pump Options

Post by harryskater_220 » Fri 02 Jan, 2015 3:18 pm

Nice, Cheers Craig. Definitely will consider the electric pump although haven't allowed for one in my loom..
Might just give the mechanical one a shot. At least with the priming lever it might be easier to encourage that fuel through the lines when needed. Does anyone know if they are a straight swap?
Yes I believe the idea of the return pipe and scavenge valve is to help with vapour locks too Bart!

CraigB
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Re: Fuel Pump Options

Post by CraigB » Fri 02 Jan, 2015 3:28 pm

The return line would help with that cooling effect of fuel flowing at full rate through for sure, but for me it still wouldn't have worked because it was on sitting it was vapourising in the pump. But if it is not a common problem then probably fine, from memory MB had it right up the front in the fresh air, Landie right down the back near the firewall etc! Mechanical fuel pump is not rocket science and I would imagine the main thing to compare is the lever length etc so it works properly. - sure someone will know on here.
Craig Baulderstone
Lurch
280s's
280SE3.5
280SL
350SL
500SEC's
560SEL's

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Mercmad
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Re: Fuel Pump Options

Post by Mercmad » Sat 03 Jan, 2015 8:29 pm

A couple of things, the lever pumps are very rare ,no0ne have been made for at least 40 years. You can buy new peirberg pumps easily enough. The return line is indeed designed to prevent vapor lock and as long as the valve on the front carb is adjusted properly so the fuel flows back to the tank at idle it does a good job of ridding the gas bubbles . Also ,the reason the fuel ines are covered in rubber is to insulate them from engine room heat ,again to prevent vapor lock.

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harryskater_220
250s
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Joined: Mon 11 Feb, 2013 7:46 pm
Model you own: w111

Re: Fuel Pump Options

Post by harryskater_220 » Sun 04 Jan, 2015 6:26 pm

Thanks for the info!

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