97 Challenger not reaching max rpms or speed...

[shocker]

This issue just started last weekend. Boat accelerates great and on plane in less than 10 secs. No wear ring or impeller issue. Seems to plateau at around 6250 rpms and 40ish on the speedo (35mph on gps). Usually got to 7000rpms and 50 on speedo. Raves are new last summer and freshly cleaned and functioning. Water regulator clean and functioning. Compression is 170 on both cylinders. Both plugs look equal in color and decent.

Rectifier maybe? Kind of doubtful because no surging in rpms but will check when I get home today. Blew out fuel lines yesterday and saw nothing suspicious.

What next?

Thanks!

[dsolie]

Re: 97 Challenger not reaching max rpms or speed...

You are running "R" type plugs?? How do you know the raves are functioning? How do you know the Water Reg is functioning?

[shocker]

Re: 97 Challenger not reaching max rpms or speed...

You are running "R" type plugs?? How do you know the raves are functioning? How do you know the Water Reg is functioning?

Yes, NGK Br8ES. Well, I'm only assuming they are functioning because they move freely up and down with good spring tension. Pull them up and they snap back into place. Is there any other way to know for sure? They are adj with caps screwed all the way in and water reg is flush. Water Reg moved freely as well but kind of sounded like something was loose on the inside. I know there is some kind of adj screw underneath it but can't recall it's purpose.

Tested rectifier and it's fine.

[wjoey]

Re: 97 Challenger not reaching max rpms or speed...

check spark plug gaps

[shocker]

Re: 97 Challenger not reaching max rpms or speed...

check spark plug gaps

.021

[woodsrider40]

Re: 97 Challenger not reaching max rpms or speed...

I also had an ECM box to go bad on one before that cuse this.