rpm issue

[20cc]

I have a modified 260 merc efi problem is I have lost 1000 rpms, it runs up to 7000 & I can run 1 person empty and run 87 and I can run 2 people loaded to fish and run same rpm and speed, it runs slick as a button, wondering if there's something that is restricting it, could it be in ecu box and can that b checked, I've replaced and checked almost everything except electrical, any ideas.......

[Jay Smith]

I find on customers motor's when the rpm on the big end falls off the injectors are most of the time flooding and acting as a soft limiter and can loose as much as 1000 rpms , after a trip to Brucato WA LA the RPM's "ARE BAAAAACCCCK".....

just my .02
Jay

[us1]

Jay is right. Also make sure the timing arm is moving the all the way to the stop. I have seen many motors with a stiff trigger wire stopping full advance. I assume you have already checked that the throttle is opening all the way.

[olmo40]

1000 rpm is about what you loose when you drop a cyclinder ?