Runs on vertical cylinder only. Pulled the air box to see down each throttle body. On startup the horizontal cylinder gets two squirts of fuel and then stops. I swapped the fuel injectors and the same thing happens again on the horizontal cylinder. When running on the vertical cylinder, when I squirt a little starting fluid in the horizontal cylinder the front cylinder runs for a few seconds. So I have spark and compression but no signal on the horizontal fuel injection other than two squirts at start up. I don’t know where to go from here. The problem was intermittent at first but now it is chronic. Please help. Thx.