'96 Challenger/ Engine Dog-Out at 4100 RPM's

[Kentac]

This started two weeks ago.
The engine works fine "once in a while". But after I run it and pull back to idle, when I try to accelerate, it won't go past the 4100 rpm mark. It's like that "over-drive" never kicks in to get it up on plane.
I put some water eater stuff in it yesterday, thinking that may be the problem. I have about 5 gallons of gas left in there. Also, cleaned the fuel filter. Worked fine when I first pulled away, but once I pulled the throttle back, I couldn't get it past the 4100 mark again.
I also have something goofy going on with my key. I posted previously about. Sometimes it works and other times I have to hit the start button without the key, then put the key on to get it to start. Also, the double "beep" is barely audible anymore. ...Not sure if everything may be related?
I appreciate any input...Thank You!

 

[Waterluvr]

When was the last time you performed maintenance on the fuel system? Lots of areas in your boat where problems can occur, most of them causing damaging lean conditions to your motor. On the fuel supply side you have an o-ring sealing the fuel / water separator filter that can leak air causing erratic fuel pump operation, the fuel selector on/off/reserve valve seals will deteriorate and obstruct fuel flow.

The carbs need to be removed, cleaned and rebuild every few years to keep everything running correctly and that includes servicing the accelerator pump circuit and nozzles and rebuilding the fuel pump, always start with a cylinder compression test then check ignition and move on to your fuel system from there.

If it hits the 4000 rpm mark with the throttle wide open and stops there, grab the choke and hold it open if that picks up the rpm's you know right away there is a fuel issue.

 

[Kentac]

Well... Carb's rebuilt about six years ago. Other than that, no maintenance. Guess I really slacked on that! I will try to the choke trick. I really think that I need to get it tuned up and running good again. At least we made it through most of the summer! Thanks WaterLuvr.

 

[Waterluvr]

Your situation with getting into a bog at 4K is really hard on the motor if the throttle is all the way open, that's 100% air with 30% of the fuel and oil needed to keep things from coming apart, scoring etc.

The choke trick is just that, don't run the boat any more than the bare minimum a few seconds is all that's really needed to confirm a fuel issue. After six years it's time to clean to clean the carbs and rebuild everything just for routine maintenance, cheap insurance more or less.

Your boat runs on a digital cdi ignition that's all integrated into the MPEM module, in your case the CDI fires directly from a trigger signal powered on the battery side of the charging circuit but it can be affected by erratic voltage from a failing rectifier which can cause a symptom similar to what your describing.