I have a 1979 300 SD that will not start, and I assumed that I was having a problem with the injection pump because I was getting fuel up to but not past it. I ordered a new pump off of ebay that looks identical except for the part in these photos. This is a photo of the original pump:



The injector pump installed on the car is the one I purchased on ebay, but the plastic white line that went to the other pump (the one on my bench) wont fit the component on the new pump.



Additionally, the part on the top of the "new" pump has the vacuum/pressure line coming out of the bottom while the "old" pump has the vacuum/pressure line connection on the top. WTF? No comprende Im concerned that the vacuum connection for the installed pump may act opposite of the removed pump.

Your 'new' injection pump isn't the correct model for your car/engine. That particular pump is from a normally aspirated engine and will not work on a turbocharged model because it does not have an ALDA. The 'similar' part on your new pump is an altitude compensator and has no way to connect to the line from the overboost valve.

In turbo models, the ALDA senses boost pressure in the intake manifold and adjusts the injection pump's fuel delivery to take advantage of the increased air mass produced by the turbocharger.

__________________
Never a dull moment at Berry Hill Farm.

bit of topic:

what does ALDA stand for?

I would be very suspect of the primer pump that you currently have. From its appearance, it may have been leaking which would create a lot of air in the system between the lift pump, that it is mounted on, and the IP. Look for the new style of pump in Fastlane ($20).

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

I agree with the last post, pretty uncommon for a IP to fail flat out like you have outlined.

Also...the new pump you got...is for a non-turbo..I have one sitting on my floor for parts

And you can take my word on this, you do not want to open up the IP to change the ALDA over from one to the other, adjusted the fuel appropriately, and try to keep the idle consistant.

Just figure out what is wrong with your old IP and fix it

The pump you bought off ebay is NOT the correct pump. The pump you bought is for a NON Turbo car. It may actually run the car, but it has NO enrichment circuit for the turbo. Take that pump off and get yours rebuilt.

Did you have a pump shop check your old pump?

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

DAMMIT! I could have sworn that the ebay ad said it was for a "300 SD" - arent all 300SD's turbo? It looks like I may need to have a shop check the old one out and give me a verdict.

Recommended shops?

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1QB0O2WTZ1QB0O3BL7&year=1984&make=MB&model=300-SD-002&category=D&part=Primer+Pump+Assembly
http://www.***************/search/productx.aspx?sid=lphrhrybiw22pj55ow2ewm55&makeid=800016@Mercedes&modelid=1194038@300SD&year=1984&cid=22@Fuel%20%26%20Air%20System&gid=6259@Diesel%20Primer%20Pump
As you will soon find out,$9.25 is certainly much less than what any shop will charge you to bench check the IP!

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

Is there an echo in here?
Jeez.

__________________
Never a dull moment at Berry Hill Farm.

So... what are you trying to say?

You're kidding, right?

__________________
Never a dull moment at Berry Hill Farm.

p5150,

I have been driving MB Diesels for 35+ years and I have never seen a no start condition caused by an IP.

I had one IP onetime that did not pump fuel to one cylinder of a 4 cylinder engine but the engine started and ran on the other 3 cylinders. Chances of this happening to 4 cylinders at once is nil.

I'm sure U have an air leak problem that is caused by a leak in the fuel line or Manual primer pump.

P E H

Thank you for the responses. I really appreciate your input!