Mothball to startup

One problem with trying to prime the oil pump using the oil pressure line is there is supposed to be a restricted fitting on the engine, unless you remove that, you will not get any oil past it. If you have a oil filter adaptor, remove the filter and use the oil squirt can and pump oil into the opening on the outer portion of the adaptor.
I use a mix of aeroshell 100W and STP oil treatment for priming.

Thanks for the great advice! I wasn't sure if I had asked a bad question with no response!

OK, nobody responded, here is how I would approach it.

Oil is fine , leave it for now.
I would disconnect the oil hose going into the back of the engine, and using a cheap old fashion squirt gun style oil can, I would pump some oil into the engine to flood the oil pump and into the upper oil galleries. You want to see oil pressure on your gauge within 20-30 seconds after start up , If you don't stop the engine.


you say tanks are dry and clean.
Let's make sure. I'd pour about a gallon in the header tank and fill & purge the fuel line to the gasolator and hopefully any crud or dust. Also to watch for leaks around the gasolator, the rubber O-rings get hard and deteriorate over time. If all is good, you will need this header tank gas to prime the engine for first start.
I would put a gallon in each wing tank and open the drains to check for dust and crud also. If clean all is good and this will be some of the first gas the fuel pump will see before sending it on to the header tank.

If you get a good engine start after priming and OIL PRESSURE is good on the gauge, you are well on your way to breathing life back into your purchase. Check or replace the 3 gas cap gaskets and make sure the little vent hole faces forward on the wing gas caps. Give the header tank float gauge a good look-see and make sure it is free to move up and down and the cork is healthy and not shedding bits and pieces.

Before first startup, chock the wheels , tie her down. Once you get a good start with oil pressure and the engine oil is up to temp, and engine is well warmed up, time for a static RPM check. Run her up to full power and see what you get for a max ground RPM. Depending on engine and model, make sure you are getting the RPM called from by the manufacturer. If numbers don't make book, time for an A&P to get involved.
Also don't forget a MAG CHECK looking for left and right mag check/rpm drop. Also, with master power on, pull on that starter to make sure the key/ground is working. With key in off position and you hit the starter, if it comes to life there is a ground problem , don't want any hot starts just by touching or moving the prop. Don't forget to turn off the master power.
After running, place some clean cardboard under the engine and the 2 wing tank drains over night to find any leaks.

That is my rookie Ercoupe owner plan of action. Just waiting for the old pros, A&P/AI's to chime in and slap me upside my head, NO, NO, NO not like that. Putting my short bus helmet on now.

Bought a coupe that was last run in 2018. Fuel tanks are clean and dry, oil changed in 2018 also. Any tips for starting this up for a test?