I have an older 200 EFI and IM pretty sure the injector part number im looking for is 18715. Everywhere i look for it they want to sell me 6. Anyone selling individuals ?

At $512 Ea I bet they want to sell you 6
That's more than the motor is worth.
What is wrong with the injector?
If they have just been setting I would send them out to be cleaned. That is a pretty rugged injector.

Im assuming its the injector. I dont have a manual but from the way they are wired two injectors fire at the same time and the other one is functioning. The spark plug in the dead hole looks as it just came out of box.

Check your ignition system. you could have a bad switch box.
Or just a dirty injector.

make sure you dont have a bad coil and chk the switch box, move the coil to another cyl , than ck for spark. if is an injector, take the injector out turn it around and take air and shoot thru the injector, see if any junk shoot out, than make a small hook up and low battery supply fire the injector, i've made a small test bed to ck injectors. a good product to run in your tank is bg products, chk the on the internet , my shop we use there injector cleaning machine and customer come back saying there engines run better than ever. try some of those things , i will look in to see any more posts

I droped off the injectors at Diesel Injection Service in Stuart Fl. John Snyder great guy he flowed the injectors and found 2 not functioning. Then he cleaned them and flowed again now all are perfect. He replaced all the seals except the bottom ones which were in good shape. Not bad for 25 an injector. Highly recommended. I should have the engine running today. Thank you guys for your input. The boat hasnt run for years and lucky for me i have 12 coils and a couple switchboxes in case this doesnt fix the issue. Compression was lowest 123 highest 125 so I should be in good shape.

Good deal, if it has been sitting for that long, I highly advise replacing the oil injection check valve (screwed into the bottom of the VST) and put a diaphragm kit in your manual fuel pump. Good insurance....
And I assume you know that motor will eat an impeller every 12 months (especially when not being used much)

Got the motor fired up sounded ok but seemed rich running in yard. Cant really know until you put a load on it so off to the ramp. Slide trailer in water fire it up doesnt want to stay running in idle. I think maybe after it warms up it will clear up wrong. I limp away from dock and try to get on plane no power extremely rich. I replace fuel pressure regulator hoping for a cure no deal. I have 37 pounds of pressure at rail is this normal?

They might have reversed the VST vent and Map hoses. it will definitely cause that scenario.
Yes that pressure is about right. it should increase a bit with higher RPMs.
ALso take a look at the temperature sensor on the Port head, if any of the wires (2 bullets) are disconnected it will run rich.

Motor runs great. Replace detonation controler problem solved.