No spark on a 1996 Yamaha 150

I bought a used boat early this summer and the engine ran amazing, since it is now winter I have pulled my boat up. After about 2 days out of the water I went to it to flush the motor out and it cranks but it wont start. I have tested spark on all cylinders and I have nothing. It has good fuel and I have disconnected the kill switch from the dash but still nothing, any ideas?

Welcome. Check this out.

Thank you so much I will try this out. Is the CDI behind the cover plate on the back of the motor?

The people I had bought it for said it is a 1996, here is a link to new decals that I had already bought for it but look exactly like the original ones. https://www.ebay.com/itm/YAMAHA-150...Decals-115-135-175-200-250-TLRV-/371989794991

Start with the spark source....the battery. Volt test for 12.75v. If good then start troubleshooting down stream. Btw, when the kill switch is activated you won’t get spark.

I am looking at my CDI now and it is a kokusandenki CU2684. It is sealed and it has 2 connectors in the bottom, 1 has 6 wires they are white with colored stripes (comes in a blue shielding from the flywheel) and the other has 3 a black red, and white. Out of the top, wires are coming out that go to one side of the motor for spark plugs, and also out of the same place there is a plug with blue brown red and black with a red stripe. The other area with wires coming out of it at the top has the wires to the other spark plugs and a grounding wire.

Quick update: I have redone some tests and I now have spark on the left side of the motor (if you look at it from the back.) I also tested resentence from the 4 pin plug on top from the stator and one said averaged about 79 Ohms and I could not get anything out of the other pins. I later read that the high coil should run between 70-90 Ohms. Could the low coil cause no spark on one bank of cylinders?