I've been spending the last few months trying to track down a long crank start problem in my m110 280CE. Being new to gassers has made this more difficult as I'm learning about what each component does as I question whether or not it is functioning.

The problem: after sitting for a long time (over night, after work, etc.), my car takes a full second to maybe 3 full seconds to turn over. It cranks just fine but won't catch and start. Sometimes when it does catch, it's a little "stumbly." Doesn't matter if it's a cold morning, warm morning, cold engine, or warm engine, it does the same thing.

Here's what I have done: New last year: ignition pick up assembly, ignition control module, coil. New this year: fuel pump, fuel filter, all under car fuel lines, plugs, wires, cap, rotor, fuel accumulator, fuel pump relay, all new injectors, sleeves, holders, rings, and just yesterday, a new cold start injector. I've also gutted the vacuum system and paired it down to the basics. Works great, no leaks anywhere, all good.

The problem still exists. My next plan of attack was to replace the thermo-time switch as I can only guess that it might not be signaling my cold start injector. However, this problem exists on the hottest days in a hot parking lot after work as well...

Basically, I need to know what the difference between a fuel damper and a fuel pressure regulator are. Does my car have both? Should I try replacing either or them? Both?

Should I be looking into the vacuum connections/system of the WUR? I don't want to go near the internals of that thing though, not nearly enough mechanical experience to consider it. Maybe the vacuum connections under there are loose or dried out? The car lived in Arizona, I've had to replace a lot of plastic and rubber.

The air slide valve appears to be working just fine as well. Half turns on the white plastic screw bring my idle speed up and down just fine, no problems there.

I'm also using high octane fuel. I was using SUNOCO's Ultra93 at the beginning of the summer after she came out of storage. I've since switched down to their Premium 91 octane. I just read, however, that high octane can cause a difficult start. Should I just try out the mid Plus 89? I really like the response and quite engine I get from the high octane though, but I could try it if that's the issue here. Does anyone know what Mercedes originally suggested? This is the low compression m110.

Any thoughts? I know this has been a long read but I'd really appreciate the help and would love to hear from the more experienced. Thanks for the help.

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1985 300D - 1984 Euro 280E AMG Clone (SOLD) - 1978 280CE (SOLD) - 1983 300D (SOLD) - 1981 300D (SOLD)