Low full throttle rpms

[mikeg205]

I had the same thing with my 95 PS205 - 41.5 is about top speed - I only got to 4200 with my 3B OJ legend and now get 4800 rpms on my OJ Force 4B... Try a different prop...if you can... just my .02 - sounds like everything normal... I wonder if tach is 100% if your hitting 41.5 - Rated speed on that boat/moter is 43 iirc.

[skiknox]

My manual says with lt1 should be 47mph and 5000rpm wot

[JimN]

Originally Posted by skiknox

Thanks Jim
The prop is a brand new acme 541 13x12 this is out there but would over torqing a prop nut do anything??? and all the other stuff you mentioned I didn't check that's a bit over my mechanical ability and tools. I do have a buddy that's a good car mechanic and has diagnostic equip so he might be able to help.

The prop nut wouldn't cause anything like this.

If your friend knows injection, have him check the TPS, MAP and ECT (coolant temperature sensor).

Verify that the spark plug gap is correct. Insufficient spark intensity will reduce power.

This is TBI and not LT1, right?

[skiknox]

it is a 95 LT-1

[skiknox]

Anyone know I good indmar mechanic particularly lt1 around Knoxville? I know America boat center is the mc dealer but would like to see if there are any other options?

[JimN]

Originally Posted by skiknox

Anyone know I good indmar mechanic particularly lt1 around Knoxville? I know America boat center is the mc dealer but would like to see if there are any other options?

Just for grins, look at the crank position sensors- if they look like they have metal shavings covering the sensors, remove that and see if it changes anything.

Other than fuel pressure, what has been changed recently? Did you change plugs, are the plug wires original (if they are, they're WAYYYYYY too old). Did you check/clean the battery terminals, ground terminals on the engine?

[skiknox]

Ran boat again today with the factory oj 13x13 boat ran 4200 at just below 40 on GPS. I did notice a rough shakey spot and a faint miss in rpms around 1200.

[skiknox]

Ordered new plug wires and going to change plugs and see.

[Mark rsa2au]

Let us know if you find a solution.

I have checked and changed everything except the fuel pump & filter (next on list), but I still cannot get the revs above 4200 with out it misfiring / backfiring. Somedays it will run to 4500rpm / 42mph and stay there on 3/4 throttle but stutter / mis etc on full throttle. Pulls like a steam train up to 4000rpm though, above this is where the challenge is!

[CC2MC]

Sounds similar to what mine did, except all I got was 35mph. It was my fuel pump and I just cleaned it out and now I get 44.9mph.