Had my 2011 250 Proxs upgraded to a 2020 250 Proxs 4 stroke on my Ranger Z521 today. Took it right to the lake to run it. Started up fine. Jumped up right on plane and accelerated fine. Was cruising in the 3000 rpm range for the first 20 mins and then accelerated up into the 4000 rpm range. Decided to take it to 5000 rpm and then it began to studder while accelerating...backed off and it runs fine. Accelerated again and it wants to drop rpms like its fuel starved. The propblem definitely is repeatable when accelerating in the 4200-4800 rpms. Any suggestions? The shop that rigged it recommended I remove the fuel line pump bulb.
Plz help!
Hitman
707-207-1781