Hi, I recently had a similar situation waking up a 280 after many years buried literally in an uncontrolled storage unit. A big question is if you think it was properly stored or not. If not, then you should also put in some relatively easy but time consuming work on other things to check the safety of all critical systems before ever cranking it.
Pawel's advice is great and the rack should move very smoothly. Mine was locked up and even after many hours of work to free it, not all of the pistons were actually free. I learned that even if the rack is free pistons can become stuck in the upper position and of course then not pressurize fuel to corresponding cylinders. So it is worth pulling the cover off and inspecting. I saw a lot of sludge in my pump, which led to rebuild, well worth it. You should also suspect the injectors and certainly pull them to inspect and clean. Mine were all bad to some degree, since they corrode over time. I would have saved a lot of time if I had just pulled and high pressure tested them out of the car first rather than discovering widely different combustion between cylinders and chasing every other sort of cause. Which reminds me that compression and leak-down checks are also a good idea and pretty easy to do. Even if fuel was purged before storage, I'd strongly recommend changing all of the rubber fuel lines, return lines, vent lines, and make sure to use fuel rated metric sized hoses that fit well. You didn't mention fuel filter but thats obvious. I'd put a new filter in and run the pump for a couple hours to circulate fuel through the tank and then pull it apart and check to see what it collected. If clean you are blessed. I wasn't and there went 3 months of my spare time. I also added a clear pre-filter outside the tank to collect debris before it could get into that expensive electric pump.
Safety first! Fuel leaks and fires can ruin your day. If you ever smell fuel, you must get to the root of it quickly. Get a fire extinguisher that wont leave residue and keep it near.
Thinking safety brings brakes to mind. You should probably flush, replace, and purge all the brake fluid and carefully look at what comes out. That will tell you what you are dealing with. Mine was basically black chunks. I then completely rebuilt the entire brake system. PMB performance will make your calipers like new if you need. Don't forget the rear pressure dampener either, not sure what its official name is but if you don't verify its working right you risk locking your rears prematurely and losing control in a panic stop. Of course you don't want to test this the hard way. And brake fluid reminds me of clutch fluid. Thats a whole topic itself but not safety related so much. I just replaced the entire system. not expensive.
I'd also recommend flushing the cooling system (first without running the engine) and pay special attention to what you see when you drain it the first time. The color and consistency of the water/antifreeze will tell you much about what happened chemically in the engine while it waited. I went through multiple purges and soaked with distilled water to try and leach as much crud out of the system as possible. Water pump is another thing that should be suspect. Mine was corroded to the point I couldn't even see the vanes very well. Its cheap to pull and just replace as a precaution...and that led to replacing every piece of water hose...even that hard to get one that looked just fine...and wasnt at all.
It's worth removing the valve cover for a look at the condition of the cam, check valve clearances, look for crud pooled in the cavities. Consider at some point re-torque of the head bolts but thats after you get it running and warm. When you put the cover back on do the "linkage tour".
I just keep thinking of stuff! I was at it for well over two years in my spare time before I ever cranked the engine by starter. At some point I realized I was doing what I've come to call the 50 year maintenance plan, which is really very simple: If it's metal, remove and clean it, if its not metal then replace it. If you think you found something you don't need to do, you are wrong. Very simple, but if you do it you will protect yourself, the car, and have a ton of fun in the process. We wont talk of the money.
Bottom line, think about your personal safety and prioritize all of the systems and items that would be needed to pass a 10 point state safety inspection. lights, horns, safety belts, etc. Then think about protecting the car itself and doing everything you can to prevent damage to very expensive and hard to find components.
I take little credit for any ideas above and thanks again to all the veterans who spent their time here in the forum, freely giving advice.
Good Luck! and remember that everything is broken until proven otherwise. -Mark
