Hello My 1985 380 SE won't start- keeps cranking and won't fire, tried putting starter fluid in breather no fire- It's allfully cold out also, when it was running it ran real smooth, so I don't think plugs or rotor I will pull a plug to make sure there is spark I'm wondering about CPS will check coil for spark also, any thoughts?

You should find some answers in these links.

Fuel Injection
http://www.peachparts.com/shopforum/showthread.php?t=142406

Engine Electrical:
http://www.peachparts.com/shopforum/showthread.php?t=142401

Spraying starting fluid into the filter won't do any good.

Remove the fuel pump relay & air filter housing. Push down on the air flow sensor plate (big round thing) and from about 12" away spray directly into hole. Have someone try to start the car while doing so. If you get nothing, it's more than likely not a fuel issue.

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A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.

It take three things to make an engine run. Spark, fuel/air mixture, and compression. If one of the three are missing, no run. No magic, just the basics.

I don't like to use ether, unless it's the only thing I have and all parts stores are closed for the holiday. What I like to use (and it works quite well) is carburetor cleaner. Ether is only intended for diesel use where there are no glow plugs and is not intended for spark ignited engines.

If the engine runs while spraying carburetor cleaner directly into the intake after removing the filter assembly, then the issue is not spark, but fuel. If it still doesn't start with carb cleaner, then the issue could be spark or compression. Rarely, though it does happen, do two systems fail at the same time. It'll likely be one of the three, spark, compression or fuel/air.

Hope this helps!

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1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

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When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.

I agree with Hispassion. Except, there is a 4th thing you must have. That is exhaust. I don't think that is your problem but I have seen plugged exhaust systems many times and they are hard to diagnose if they are completely plugged. Just keep that in mind.

Paul

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84 500 SEL (307,xxx miles)

So true. If you don't get air out, you won't get air in! Rare problem, but it does happen.

On small engines, this happens frequently as mud daubers like to make homes in the little tail pipes of little engines. On an automobile, it would likely be a prank potato in the tail pipe or a completely plugged converter.

Again, not likely your problem, but it has happened.

__________________
1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

Expert RV Generator Repair
Go To: MiGen Repair
When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.

You also need correct timing.

True, but I would categorize this under "compression".

__________________
1992 300CE - 157kMi (my white beauty)
1992 300CE - 220kMi (sold)
1990 300E - 189kMi (sold)
1990 300SL - 102kMi (salvaged parts available)
1986 300E - 230kMi (salvaged parts available)

Expert RV Generator Repair
Go To: MiGen Repair
When no one else can, I do!

We judge ourselves by our intent.
We judge others by their actions.

Since these are interference engines, I was referring to correct ignition timing, as in a failing CPS, damp/cracked/bridged dist cap, cross firing wires, malfunctioning CCU, ECM. The kind of thing where you check and see that you have spark, gas etc but it just won't start, because you don't realize it's firing at the wrong time.

On a non-interference engine, like the older Volvos B-23s/B-230s, correct mechanical timing is also essential to start it. If the timing belt jumps or breaks in a non-interference engine it will crank like mad, have spark, gas and everything but it won't start.