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twotops · Joined: 27 Jan 2015 Posts: 1 Location: Kansas

I was told you guys may be able to point me in the right direction. I inherited a 109000 mile 78 450SL. Was parked two years ago because it would die and had poor acceleration then would only start and idle. I couldn't get anything to work at first. I replaced the fuel pump and filter and now it starts on the cold injector then dies. I can pour gas in and it runs great for a bit. I have fuel in both lines at the warm up regulator and it measured 23 ohms across the contacts. The air flow and switch work and I hear the relay clicking when I depress it with key on. I have opened the gas lines individually everywhere and get a pretty good pressure squirt except the injectors on the fuel distributor.The air flap has a steady resistance under pressure and even cracked wide open it does not leak fuel out of any injector lines. I have the manual and have studied the way this works but it still seems like it should be pushing fuel to the injectors. What am I missing?
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It's always something!

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Probably gummed up fuel distributor. Time for a rebuild!
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

pmcaya2 · Joined: 24 Nov 2005 Posts: 191 Location: Scio, NY USA

I assume that you're getting gas to the regulator since the cold start injector is working and that you confirmed that there are no vacuum leaks in the intake housing. So a rebuilt or new fuel distributor might be the right answer.
I don't know if it can be cleaned internally. Since the 450SL CIS system is somewhat common to German cars of that vintage, I'm providing a few links - the first is a link on general function and the second is a trouble shooting guide. The others are Mercedes specific. Hope that this helps.

http://www.n56ml.com/CIS.html
http://audi.humanspeakers.com/tuning-cise.htm

http://arrc.ebscohost.com/ebsco_static/repair-tips/8852CH15_BOSCH_CONTINUOUS_INJECT
ION_SYST.htm

You want to look at the EFI info, 07.4:
http://handbook.w116.org/engine_75.htm
http://www.w116.org/
http://www.w116.org/library.php
http://handbook.w116.org/