7.4 Gi power loss issue

[Oldsmoduck]

I have nagging issue with my port motor and hoping someone in here can help, I have a pair of 7.4 Gi's in a 1999 Four Winns 328 Vista. I push the throttles up to get on plane, both motors come up and right at 2k RPM the port motor loses power like its bogging. I can bring both engines back to idle and it will do this over and over. the engine never stalls. I can also hold it about 18-1900ish and it will run forever like that.. as soon as I give it any more load, right at 2k it falls back

Port motor has 43psi at idle and 48psi under full load when this happens. low pressure pump is 7psi. I even swapped them starboard to port to see if there was a volume issue, nope.... filters are new. check valve is clear, in fact ive pounded out the ball in the valve on this side. Tried a new ignition coil. nope again. distributor is brand new along with module and pickup.. I have solid 14.1 voltage going to the coil under load. Ive checked it for codes, nothing.

It almost feels like it may be going into a protection mode? I cant think of anything else that might cause this... Need someone who is familiar with these. Thanks in advance!

 

[MariahZ220]

Try checking all your spark plugs. Last year I had an issue where it ran great at idle and low RPM but when I gave it throttle, it wouldn't run at all. turned out I had a spark plug that had a crack in the porcelain and it was sparking against the block.

 

[robwny]

I have 5.0 Gi motors was going through the same thing I've done everything you've done. First question is that the right fuel pressure you should have I know my motors are smaller so maybe it's just less. Under load my motors are supposed to be 29 pounds plus or -2 I was just confirming.

My one motor would run up to 3000 RPMs and then just fall on its face. It looks like I finally got it it was the throttle positioning sensor. You can switch it from one motor to another and see if the problem jumps.