Boat looses power at 3300 rpm then takes off

[cruisersveesport]

I have a 1987 Cuisers with a 454 mercruiser and Bravo 1 drive. A rochester 4 barrell carb with electric choke

My problem is when I running, I go to open my throtle, the boat dies as I hit 3200 rpms and then shoots off right up to 3800. I hear it sometimes spit through the carb as it dies, feels like it is going to stall and then takes off. Runs fine when until I go to slow down and hit that range. It would starte to surge and drop off

My RPM's were capping out at 4000. I would have no midrange from 3200 to 3800 as it would not run smoothly when I tried to back down.

It feels like when the secondary are trying to kick in, the boatdies and the takes off. The carb was replaced a year ago but never in the water until now.

I also have older fuel in the boat. I tried to burn off as much as I could then added fresh fuel. This actually got me up to 4400 rpms. I still have the midrange problem.

I also noticed my temp guage is maxing out around 140 to 150. Could a colder engine cause this problem? Is there an easy check for the temp guage?

I also do not have access to premium fuel and run plus could this be a problem? Are there any additives that could help?

 

[freddyray21]

Re: Boat looses power at 3300 rpm then takes off

will it run at all in the mid range or does it just bog down upon acceleration or deceleration? Seems like a fuel problem. Old gas left in a rebuilt carb leads to needing to rebuild the carb.

 

[cruisersveesport]

Re: Boat looses power at 3300 rpm then takes off

It idles fine. Runs fine up until the rpm's hit 3200 or 3300 as I try to push through it, it bogs down and takes off and surges if I drop the idle down into the 3200-3800 range.

 

[Acer2428]

Re: Boat looses power at 3300 rpm then takes off

Sounds like you're dumping fuel on the motor.

Rebuilt carb? Was it adjusted for your boat?