Re: Can Not Figure It Out,,Please Help
 

what props do you think would be best to start with. And where from and thanks again

Re: Can Not Figure It Out,,Please Help
 

I'm assuming the boat's a Donzi Z33 right ?

That boat and that power, I would think that
the 23's would be about right, (they just need to be the same)

Start with a set of 23 mirages.

I've had good luck with Houston prop ( He's also a board member)

jt

Re: Can Not Figure It Out,,Please Help
 

All else being equal, if you still have the problem after getting props, i would suggest you check the hull. If switching prop rotation made a drastic effect, you could have a hull problem that interferes with clean water flow to the props when turning the correct rotation that is less drastic when spinning them opposite.

Re: Can Not Figure It Out,,Please Help
 

Well today I did a compression check on both engines and are 100% good. also checked the tachs and they are 100% accurate. So we are down to props and still can not figure the rev limit thing now. anyway of checking the ecu etc etc to see if anyone has tampered with it. And thanks again for all the help

Re: Can Not Figure It Out,,Please Help
 

Try hooking up a vacuum gauge & check the reading at idle & blip the throttle.
If the slower engine has less overall vac, it may indicate an exhaust restriction.

Cool forum BTW

Re: Can Not Figure It Out,,Please Help
 

Have you considered trying swapping the ECUs and see if the problems reverse, that would indicate one was tampered with. Now the $100 question how hard is it to swap them, think just a matter of unplugging and swapping but someone with more smarts will hopefully know..

Re: Can Not Figure It Out,,Please Help
 

Ok heres what has been done and still a problem exists.
1.bought new matching props and went with 25p mirage plus.
2.changed plugs, cap and rotor to be safe.
3.changed fuel/water filter and didnt have a drop of water in them.
4. cleaned out the flame arrestors and cleaned the intake.
5. checked fuel presure (not running the boat) and both read stb side 36psi and port side 34 psi and they hold presure for a good long while.
6. found one problem and had a bent shaft on stb side and rebulit the lower foot w/ a new shaft.
7. changed both fluids in drives and both showed very very little signs on metal if any at all.
8. checked trim, and both trim exactly the same when cruising.
9. checked timing at 3k rpms and both show 30 deg, and 8 deg idle.
10. checked compression all are within 10 pounds of each other.

so all in all the problem still exist. now with the bigger props the stb engine runs at 3000 rpms and port engine runs 3300 rpms at midrange. at WOT the stb runs 4100 and port runs 4700. what should I try next. and the P/S pump is on the port side.(the one that runs higher rpms).
please if anyone has a clue.

Re: Can Not Figure It Out,,Please Help
 

Are you sure both motors are the same? I have seen people throw motors together and put different cam shafts in them. Also, have you checked plugs and wires? Usually a 3-400 rpm difference is one cylinder.

Re: Can Not Figure It Out,,Please Help
 

changed the plugs with the same affect havent changed the wires yet but will do.
And the motors looked untouched totally factory, so I would have to say nothing has been done the factory paint on the timing cover etc etc havent been touched.

Re: Can Not Figure It Out,,Please Help
 

Also forgot to mention I dont hear one single miss in either engine.