Bought two 2006 vx110 sports. One was in working order, took it out and 1.5 hours later found out I had the joint pipe leak everyone talks about. Got new joint and sealed it, it runs great and is loads of fun.

The second ski was basically thrown into the deal just so the guy could get them off his hands. He really didn't know what was wrong and thought that it needed a new head gasket.

I was trying to start it. Figured out there was no starter relay so got a new one. After cranking for a good while still wouldn't fire. Oil was like milk chocolate. I pulled the head cover off and 4 exhaust valves were stuck. Pulled the whole head and found half an inch of crud sitting on top of the pistons in the cylinders.

I thoroughly cleaned the head. Changed oil. Lapped all the valves. New springs on the ones that needed them. Reassembled and reshimed. New head gasket. Got everything back together and after cranking for 10 minutes got a single backfire

All the coils are firing with decent spark with new plugs, all the cylinders have enough compression to blow my hand off the hole, I replaced the ecu with the one from the working ski. The fuel pump isn't working but I've manually poured gas and or starter fluid into the injector line and put pressure to the fuel log (this is how I get fuel for a backfire)

Any advice?
Kind of don't know where to go from here. Seems to be electrical of some nature. I thought it might be my cam sensor but Replaced and it's the same issues. I'm assuming if it was the throttle sensor or stop switch I wouldnt be getting a spark.

Of note everything is back together except for the air filter box and the electrical connections to the fuel pump