1980 Mercedes 300SD Starting problems - Injector or Fuel

When it is cold out, I can NOT start my car. If I warm the car up (pushing into the garage and warming it up over 40 degrees F. It will start.
However, it will only start if I first depress the gas pedal and then
take my foot off the gas. It will ONLY start with the pedal NOT depressed. It really sounds like a fuel problem.
Once the car starts, I can give it gas and then it runs GREAT, idles (with only a slight knock)
I KNOW it is not the glow plugs (I have pulled them all out, connected them just like when they are in the engine and watched them all glow).
I recently replaced Both fuel filters (primary and secondary).
At one point on the secondary fuel filter, it did look like it may have been sucking air but I sealed that up (around the bolt that holds the secondary filter up). I discovered it when I filled the car up to the top with diesel with rear tires on jacks and saw diesel come out the bolt on secondary filter but that is not happening anymore.
The only thing I can guess is: 1) Fuel Injectors 2) The actual Injector. Question: how hard is it to check for compression? Also, someone said there is some vacuum hose to the injector that may be causing the problem, Can somone tell me what his is and if this could be the cause of the problem. 3) Valves need to be adjusted
ANY other thoughts out there or simple checks I can do?
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I've owned this model for 26 years and will help you at Usenet.alt.auto.Mercedes, not at some commercial, content rip off site.
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2007 T.G.Lambach. Publication in any form requires prior written
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I have two of the same year and I have a problem with both cars.
""-->> T.G. Lambach" wrote: > I've owned this model for 26 years and will help you at > Usenet.alt.auto.Mercedes, not at some commercial, content rip > off site. > > -- > 2007 T.G.Lambach. Publication in any form requires prior > written > permission.
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That car's valves need to be adjusted every year. Do that first.
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http://www.AutoBoardz.com/1980-300SD-Starting-problems-Injector-Fuel-Mercedes-Benz-ftopict204847.html Had a similar problem with my '81 300D. Started fine with a short shot of starter fluid in the air intake. Started and ran perfectly for the remainder of the day but presented the same problem the next morning. I had replaced the glow plugs with the Autolite brand. Bad move! Got some Bosch on the internet with the kit and the new, longer-active relay and now it starts like a new car. Nothing like the original.

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