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-   Archive through May 29, 2009 (http://www.wakeworld.com/forum/forumdisplay.php?f=702328)
-   -   Boat won't get over 3500RPM (http://www.wakeworld.com/forum/showthread.php?t=699298)

tl_hereford 05-24-2009 7:08 AM

I have a 2000 Supra Launch with a 325 Indmar assault. Motor runs great until I slam it with sacs. Around 2.5k of ballast and the motor will not go over 3500RPM with the throttle to the floor. So I turn the boat off and kill the master power switch to cut all the juice from the batteries. Start the boat back up minus a 250# sac and she runs like a champ. I dont get it? Even if I needed to reprop the motor is still going into a "protection" mode. Any ideas? I had all the filters and fluids changed about 30 hrs ago so I should be good on that.

266crownlinebr 05-24-2009 8:30 AM

Just a guess, but if you are killing the power to the pumps for the ballast, maybe it has something to do with how they are wired that is killing the altenator or some other part of the electrical system.

greg2 05-24-2009 10:05 PM

I don't think your going into a "limp" mode. At a certain point you'll only get "x" rpms if you're over weighted (unless your transmission is slipping).

tl_hereford 05-25-2009 5:36 AM

Aw that sucks! I thought for sure that I would be able to take on more than that. Any prop guru's out there think this can be fixed with a prop swap?

rallyart 05-25-2009 8:29 AM

What speed are you doing when it tops out? If you are not fully on plane then you might have just powered out, from not having enough torque, and a prop change would fix it. <BR>I can't think of any 'protection mode' that would kick in at 3500 unless it's a knock sensor and the way to fix that would be to run higher octane fuel.

denystaucd 05-25-2009 10:21 AM

Umm couple things that come to mind. Typically what your describing is an exhaust obstruction. Could it be that your back of the boat is so low, the water is still pushing hard on the exhaust flaps. Creating to much back pressure. I've seen this a bunch of this in trucks with plugged cats that will not go above 3500 rpm and most people tend to think it's the tranny slipping. <BR> <BR>Also this condition semi describes a distributor failure, but you would get popping through the throttle body at 3500 rpm. <BR> <BR>Cheers, <BR>DC <BR> <BR>(Message edited by denystaucd on May 25, 2009)

denystaucd 05-25-2009 10:22 AM

Is the supra a single exhaust outlet boat?

krbaugh 05-25-2009 11:29 AM

I agree with Art At some point you get to to much weight for the prop/engine combo to get you on plane.

tl_hereford 05-25-2009 2:38 PM

Its dual exhaust. And no I'm not fully on plane. And yes sometimes it will jump up to 3600 or 3700 but then it will go right back to 3500. Also when it starts to struggle there is a strong rich exhaust smell. But like I said if I cut the master power it will run 4000rpm for a bit then back to 3500.

luchog 05-25-2009 6:43 PM

how does it run when unweighted?

tl_hereford 05-26-2009 5:57 AM

Great. no problems @ all. Only under a load and sometimes in the seldom double up runs.

boarditup 05-26-2009 6:08 AM

Oil starvation?

tl_hereford 05-26-2009 6:25 AM

Oil level is fine I check it before I take out my boat every time. And my pressure while I'm running never falls below 40 psi.

luchog 05-26-2009 8:26 AM

You could also check the impeller for missing blades. <BR>Bad fuel is another option.

roomservice 05-26-2009 9:17 AM

what's your top speed unloaded? I'm thinking if it's fast (40mph or more) then you may just need to shorten the pitch on the prop a little. If you want to slam it some more, shorten the pitch some more. You'll just lose the top end speed, and really, what wakeboarder really cares about that....? <BR> <BR>Exhaust restriction is also a possibility, but i bet it's just the max on that prop/boat combo. Re-prop it, you'll enjoy the better hole shot too. <BR> <BR>good luck, prob an easy fix.

bmartin 05-26-2009 12:24 PM

+1 on lower pitch prop if you want to keep running that weight. <BR> <BR>This might make you feel better, but if mine is slammed with 3000lbs plus, it won't get over 3500 RPMs either and barely gets on plane. Just pushing too much weight for that prop pitch / engine torque. I don't load it up that much any more.

denverd1 05-26-2009 2:15 PM

Sounds like it could be advanced timing issues ("dist failure"), but more likely just an overloaded boat... new prop will fix ya better than new.

tl_hereford 05-26-2009 3:30 PM

bmartin what prop/pitch are you running?

rallyart 05-26-2009 3:39 PM

Nitrous Oxide will get you our of the hole really well. <img src="http://www.wakeworld.com/MB/Discus/clipart/happy.gif" border=0> <BR>A 150 hp kit should do the trick.

tl_hereford 05-26-2009 4:05 PM

LOL.... Right.

bmartin 05-26-2009 9:07 PM

Luke, IDK what pitch, 4 blade OJ that used to be a back up that I put on when my ACME was dinged but haven't switched out yet. The pitch is too high, my orignal prop did OK.

mtnm2 05-27-2009 9:26 PM

I have a similar problem with my malibu. It will not go over 3700 no matter what. I replaced the rotor and cap. Fuel filter and the alternator was bad so I replaced it. Still have the same issue.

tl_hereford 05-28-2009 12:38 AM

Sucks to be us. I think Im gonna bite the bullet and take her in for a check up. What motor do you have?

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