Fuel pressure regulator 69 280sl

[travellerdogs]

Hi I am redoing my fuel system on my 69 280sl and need a diaphram for the fuel pressure regulator on the return line to the tank. This regulator is after the fuel injector pump and apparently regulates the pressure in the system. Where can I get a rebuild kit for this or where can I find a new unit. I am in British Columbia and mostly buy my parts online out of the US. Appreciate any help on this if anyone knows. Thanks.

[Benz Dr.]

The fuel pressure regulator is in the outlet of the IP. What you are looking at is the fuel dampner. It softens the pulses coming out of the IP and this is supposed to reduce noise in the return fuel line.
Since I've never heard this noise, they must all be working on everything I've ever seen.  ::)Somehow I doubt that, which makes me think it can't be all that important, but since it's part of the system, it's nice to know it's working.

[wwheeler]

I have rebuilt mine and it is easy. You need a compression spring and diaphram and seal rings. If the flats on the fittings are buggered up, you can replace those as well. You can also buy a new one although I think they are on back order.

Seal rings:
(1) 636 997 02 44 and (2) 007603 014100

Diaphram - #127 070 00 52
Spring - #127 993 00 01

That should do it.



 

[travellerdogs]

Thanks Dan and Wheeler for the info. I finally identified it this morning from scouring the BBB. That book is quite intimidating, too much information. I have been reading the forums and I see that Dan is still the one that I look for for practical answers. Thank you Wheeler for the part numbers, guess those are for MB parts for ordering at the dealer. Local 3 Point here on the west coast are quite helpful. They would have been my next visit. Just rebuilt the old style Bosch pump but am not getting the 1 litre in 15 seconds. Got it before I hooked it up to the car. Pumped big time in the varsol tank, got the litre in 11 seconds. maybe the varsol screwed it up. Getting a litre in 25 seconds now on the car. I just removed it again and will check it on the ground with a battery hookup. I have 11 volts at the connections. I have a donor pump for parts minus the brush holder. Both bellows were good when I first rebuilt it. Car has been off the road since 89 in a heated garage so not sure when the PO last fired it up before he passed away. Fuel was really old and smellled like varnish. been cleaning all the lines and darn near everything so far except the IP. Hopefully it won't be varnished up. Taking it a step at a time. I'd be lost if not for this site, a godsend.

[twistedtree]

If you get good flow in a test fixture, and slow flow connected to the car, I'd suspect blockage in the tank.  These tanks get crudded up pretty easily.

[travellerdogs]

Just pulled the fitting on the inlet of the pump and I had repaired the screen in the fitting with a piece of screen to repair the holes in the little screen fitting attached to the fitting. I suspect that the extra piece of screen was impeding the flow. I took a fitting off the donor pump and am presently soaking it in my cleaning tank after which I will clean it. Also I rebuilt the tank and maybe there is some left over crud partialling  blocking the screen on the new bottom plug that I ordered from mercedes. The feed tube gets the fuel at the bottom of that new plug which has a screen filter attached. Quite an ingenious setup. I will take the plug out and also blow through the feed pipe from the outside to make sure there is no blockage. Which means I have to drain the tank again. Thankful I have a hoist to work on. I follow the rebuild instructions in the technical notes on this site. Great instructions.