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-   General Boating Discussion (https://www.offshoreonly.com/forums/general-boating-discussion-51/)
-   -   Formula not up to speed. Help... (https://www.offshoreonly.com/forums/general-boating-discussion/223697-formula-not-up-speed-help.html)

speedreeder 01-31-2010 07:04 PM
Easiest First!!!!! Change To Good Known Props!!!!!!!!!!

theadamv1 01-31-2010 07:13 PM
i would double check the timing, and if that is ok, try swaping carbs from one engine to another, to eliminate a carb issue..

AIR TIME 02-01-2010 02:34 PM
Originally Posted by 336Formula (Post 3035821)
Bottom of boat is very clean. Up to about 4,000 rpm, throttle is in same position for both engines. When you push up on both throttle levers at same time the port engine revs up to about 5300 and starboard only to about 4700. So you have to back off the port engine throttle to bring it back to 4700 but does not seem like the boat slows down that much.

BTW, thanks for all the attempts so far.
sounds like prop slip

US1 Fountain 02-01-2010 04:17 PM
drive showers

Fixxxer22 02-01-2010 04:32 PM
Originally Posted by AIR TIME (Post 3036487)
sounds like prop slip
ditto. I had a 21p mirage on my boat for a few minutes after i got my new power in it. the pvs caps were missing and it would get on plane and it would slip when i cracked power to it. it was the incorrect prop i just wanted to see what it would do. i woud switch to known good props and then if that does not work check timing and swap the carbs from engine to engin to eliminate that concern. the beauty of having two engines is that they are great for diagnostics. the ultimate donor.

336Formula 02-02-2010 12:29 PM
We put the drive in forward gear and attempted to turn the prop ccw. Prop would not turn.

Unfortunately the boat is currently on the lift having some touchup paint work being done. And I cannot put it back on water until this weekend.

I have a boat mechanic from a local shop telling me that it is the engine coupler failing. He says that Friday he will pull the engine, replace the coupler and if it does not solve the problem, I owe him nothing. He is very confident in his ability so I guess we will see what happens this weekend.

Sunshadow 02-02-2010 12:42 PM
Originally Posted by 336Formula (Post 3037038)
We put the drive in forward gear and attempted to turn the prop ccw. Prop would not turn.

Unfortunately the boat is currently on the lift having some touchup paint work being done. And I cannot put it back on water until this weekend.

I have a boat mechanic from a local shop telling me that it is the engine coupler failing. He says that Friday he will pull the engine, replace the coupler and if it does not solve the problem, I owe him nothing. He is very confident in his ability so I guess we will see what happens this weekend.
I like his confidence.

Wildman_grafix 02-02-2010 12:43 PM
2 Attachment(s)
Originally Posted by 336Formula (Post 3037038)
We put the drive in forward gear and attempted to turn the prop ccw. Prop would not turn.

Unfortunately the boat is currently on the lift having some touchup paint work being done. And I cannot put it back on water until this weekend.

I have a boat mechanic from a local shop telling me that it is the engine coupler failing. He says that Friday he will pull the engine, replace the coupler and if it does not solve the problem, I owe him nothing. He is very confident in his ability so I guess we will see what happens this weekend.
If it's a bravo coupler they don't slip. It is a all or nothing. You would see some shavings around it. here's two pictures, one was trashed, prop won't turn at all. The second one is close to failing but you could not tell at all. Worked just like a new one, but not for long.
You can see if the shaft turns it will trash the coupler, no way could it turn the prop and grab at all.

Griff 02-02-2010 01:11 PM
Originally Posted by Sunshadow (Post 3035891)
Here's a long shot. Could the upper gears on the port side be worn to the point that they slip (or skip) under the high speed load?
NO. They are either good or trashed. You would here all sorts of grinding and the drive would not do a thing.

Originally Posted by 336Formula (Post 3037038)
We put the drive in forward gear and attempted to turn the prop ccw. Prop would not turn.

Unfortunately the boat is currently on the lift having some touchup paint work being done. And I cannot put it back on water until this weekend.

I have a boat mechanic from a local shop telling me that it is the engine coupler failing. He says that Friday he will pull the engine, replace the coupler and if it does not solve the problem, I owe him nothing. He is very confident in his ability so I guess we will see what happens this weekend.
He may be confident, but not very smart. A coupler may let go slowly............ by slowly, that is a couple minutes at most at higher rpms.. Once it starts to go bad, it takes about 30 seconds before its completely trashed.

Griff 02-02-2010 01:16 PM
Things that need to be done.......................
Verify tach accuracy and speed accuracy
Check timing on both engines
Try a known good set of props
What are the drive gear ratios????

The boat should run about 40mph at around 3000 rpms


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