Set up questions and thoughts

[Lorenzo D]

Hi Guys, I'm in the process of trying to dial in my boat height and proper prop say that 10 times fast) lol to get more speed from my boat. It's a 901cdx with 200hp otimax. I have a 10" manual jackplate and it was set at 5 1/4 inch below pad running a high five 25pitch prop. My hole shot was a monster with full load. My top speed is around 57-58mph.

I just raised the prop to 3inch under pad. I made a run and didn't see much difference in hole shot or speed. I then tried same height with a tempest plus 26pitch prop and the hole shot was not as good and my speed was about 59mph max. Not that big a difference.

Any advice on where to go from here. One problem I have is my rpm gauge is not working. Jumps around and I'm looking to get it replaced. The other issue might be the water pressure gauge. At WOT it reads about 40psi and at idle it reads 25psi. Is this normal? Do you think this gauge is shot too? Thanks for any of your tips you might have.

Update June 24 2014

I have replaced my impeller and have a used gauge ordered from eBay. Should be here soon.

I tested a 25p tempest plus and lowered my jackplate to 3.5 "below pad. Hole shot was decent and top speed was about 60mph but I still had 1/4 inch trim to go but my rooster tail was pretty high so I didn't want to risk trimming more not having a proper gauge. So I think once I get the gauge and adjust height I should see speed over 60mph. I think I'm close to getting the right prop. I will update once all is done.

 

[AirForce]

Ok, as far as set up goes - I ain't worth a toot for that BUT the RPM gauge reading odd is a sure sign your regulators (one or both) are burnt. Could also be the stator too. Look very carefully in those areas for scorched/burnt, discolored connectors (signs of overheating). You might also have to unbolt the regulators as well to look at the backside (epoxied side) and see if its bubbled up. Look up under the stator for magnets missing, discoloration etc and all connections. take some pics to show us as that'll help too but use a photo hosting site like photobucket so we can see it full sized, easier on my eyes.

As for the water pressure, was the impeller recently changed?? Always check the source - the water pump area for loose/torn gaskets, obstructions. If the housing is scarred or the base looks slightly chewed (minor) then replace the whole thing - water pump housing, gaskets, impeller (housing kit) and also change out the base (normally sold separately) as its part of the lower unit, and not exactly part of the water pump assembly (although everything for water pump sits on it).

Now IF this water pressure gauge didn't have the water drained out of it during the winter months and it sat outside, then yes, if could have damaged the gauge. If that's the cause, replace the gauge BUT also put in a T valve where you can access it. Make a note to drain the water about the same time you change lower unit oil prior to first freeze (or drain it everytime if you fish through the winter). It'll save you headaches later.

Note on regulators - just because you might find burnt regulators - don't assume that's the only damage there is, you'll need to have the rest of the ignition/charging system checked. Also replaced those regulators in pairs. If you're going to do the work yourself, I HIGHLY recommend an OEM Service Manual for your motor based on SN range (specific to your motor family), it'll be very detailed on how to perform those tests etc.

 

[Lorenzo D]

ok I'll check what you ask. I don't have much experience with the parts your talking about. I'll try and find where they are. I'm thinking of changing the water pump at the end of the season. Maybe I could do it sooner. I get a good stream of water out the tell tale. What is the normal range the water pressure should read. I've seen people say the range should be around 18psi wot and 5psi at idle. Is this what everyone is getting. I hope it's just a bad gauge? I'll get back to you when I find something out. Thanks

 

[AirForce]

If you're not familiar with what I mentioned, then take it to the shop asap. I would NOT wait till fall to change the water pump until you can determine if the problem is the gauge or not - its easy for a shop to check it if they know what they are doing. But if the impeller wasn't changed last year, get it done since you gotta drop the lower unit anyways to check the water pump. stream of water has NO bearing on the water pump itself. This is where a smartcraft mercmonitor pays for itself if its smartcraft capable.

 

[Lorenzo D]

Airforce, I talked to a merc dealer and my engine 2008 optimax 200hp does not have regulator or stator. I'll post any info I get once I get a new gauge. Thanks