Fuel pump 1971 350SL

Hello, I own a 1971 350SL.

Until last year I had an original 107 pump, that stopped working in winter. I replaced it with Meat Doria 76034/1 inline pump which is 3,0bar pump and is a replacement for Bosch 0 580 464 006. And then my 1971 350SL started acting strange. Hasitation when accelerating, hasitation to start after quick stop,...

As I read through DJet system explanation, I saw the statement somewhere, that it is ok to use Bosch 05 580 464 021 (3bar Porshe 944 pump) or Pierburg 7.21287.53.0 pump. I already ordered Pierburg non return valve and will get it today.

On some other forum everyone recommends Nissan pump as it is supposed to be identical to original pump...

As I can see that here lives a true doctor of DJet system, I would like to ask, is it really so important to buy a Nissan pump or is it ok to buy a 3.0 bar pump as you reccomend? I am just about to order a Nissan pump...

And then there is a problem of fuel pressure regulator and damper... how can I know if they are ok? Can I buy some other regulator with manometer to see if the pressure is truly just 2.0 to 2.1 bar? Or just the original MB?

Thank you for any answer!

Best regards, J

Hi J. ???,

we usually sign by first name to give politeness a better chance.

Well best is the original pump as it has a valve that opens when fuel line to engine is blocked and ensures a maximum pressure of 3 bar. Fuel pressure regulator would also handle a pump for 5 bar system pressure as in K-Jetronic. This pumpe would create roughly 8 bar when line is blocked. And it also creates much higher pressure peaks when injectors and pressure regulator open and close. These peaks are the dangerous part. They can make damage on injectors and on diaphragm of pressure regulator.

That is why we recommend the pumps made for 3,0 bar system pressure as replacements. You found those nos from Bosch and Pierburg in my compendium. There are however also pumps with a similiar housing as the original one. Mercedes used such a one also for K-Jetronic in first cars. Later they were all swapped in field to the modern design.

So that means that the Nissan pump could look the same but have a different valve spring allowing a different max pressure. To be honest I do not know that and that is why I do not comment on the Nissan pump.

Best option: Try to repair original 0 580 464 005 pump if it only leaks on pump head. I wrote in my compendium which O-rings you need. If fuel comes from the motor housing or electrical connectors: Forget it. Use the replacement pumps that I mention in compendium.

Regarding pressure regulator:

It can be that your intermediate pump has damaged the diaphragm inside of 0 280 160 007 regulator. You will need a gauge with a reasonable class of accuracy. I'd propose a class 1,0 manometer with a range of 2.5 Bar. Why? Class 1.0 means 1% accuracy on max range value, so we have an accuracy of 0,025 Bar.

You can try to pull a vacuum on pressure regulators flange towards pressure damper. If it holds tight and does not drop quickly, its diaphragm is still okay.

Hello,

my original fuel pump died electrically. Is this even possible to repair? Or is it only possible to repair leaking working pumps?

I will test the pressure regulator next week when I will get to my car. If the membrane is torn, is it better to fit the original MB pressure regulator or the more modern regulator? Perhaps even a regulator with manometer installed?

Thanks, Jarni

Hi Jarni,

ever repair is possible. It is a matter of what is broken, how much effort you want to spend and what spares you get. I have never seen an electrically broken fuel pump. What exactly is broekn there? Or is it just worn coal?

You will not find 0280160007 pressure regulator as new any more. No more production since 2 years. So you have find a used one or use whatever you find and fits.

I just went to test if my old fuel pump is really broken. But now if I connect it directly to a battery, it starts working... what could be wrong with it last winter when it did not show any signs of life anymore?

Thanks, Jarni