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jamisond

Poor Acceleration 2003 Sunesta 223

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I recently purchased a 2003 Sunesta 223 with the 5.0 GXI Volvo-Penta motor. It has a Duoprop outdrive with 1.95:1 gear ratio pushing F5 props. I am seeing terrible acceleration times to plane. I usually run a full boat, 4 to 6 adults 2 to 4 kids and am getting planing times of 11 to 12 seconds. Pulling a 200 lbs. wakeboarder increases my plane time to 20, 21 seconds. I am constantly having to run wot just to get the boat to move. When pulling a tube, it takes a while to plane and I have to have the accelerator down when I turn, or I loose so much power, that the tube ends up being like an anchor. When I hit the holeshot, the tach reads 2700 rpm until I get on plane and then it will start climbing. I was running wot on plane at 40mph and hitting rpms of only 4200.

I do a lot of watersports and care more about holeshot acceleration than top end speed. Does anyone know why I am not getting a decent holeshot with my setup? I recently had the engine serviced and compression checked. Everything was spot on. I did replace the screen in the fuel regulator with the eclip, but experienced no additional power. Is there something the mechanics and myself might be over-looking? Would a change in props help, or am I just underpowered for my boat?post-45997-0-96994200-1436508727_thumb.j

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That engine should be fine; you're not underpowered. My BiL had the same boat with 5.0 Merc/Alpha 1 drive; we once had seven skiers up with it (though it took us a long time to come up).

Something's up. If engine checks out, I'd be looking at different propset.

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I had the engine looked at and compression checked before I bought it. Everything came back a-okay. I had the engine serviced after I bought it, no problems. Not sure where to begin looking for a culprit. I do believe the fuel injectors may be dirty and that their might be paint in the fuel cell, as there were flakes on the screen that I removed from the fuel regulator. Not sure if that would be causing the poor acceleration.

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Like Futzin said, something is not right. That's a very quick-planing hull and does not require a lot of power for good performance. I have the 5.0 220HP Mercruiser in mine. With an 18P four blade prop on my alpha, I can be on plane with six adults on board, full tank, and not even WOT throttle during planing, in about six seconds or less. I have had up to 12 people on board, and see almost no increase in planing time with that prop. WOT with that prop gets 5000 RPM and about 40 MPH. Right now I have the 20P on it, and planing time is a little longer, but still very quick. My WOT dropped to 4400 RPM at 44 MPH. I have no idea how those prop pitch numbers compare to the Volvo props, but you should be seeing similar performance.

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Your setup sounds fine. Those duo props should have no problem planning or pulling wake boards. You are not firing all cylinders, check the plugs and injectors again.

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What about the seating of all your passengers?? If they are all piled up in the stern area that would make a difference in getting on plane...The heavy folks need to be in the front...and split side to side to even out the ballast aspect...

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I've tried different configurations on seating, nothing really seems to make much of a difference. I ran the boat at the lake yesterday. After crossing the lake I beached and turned the engine off for about 20 minutes. Started it up, took off and moments later it sputtered and died. Couldn't get it restarted, sounded like it was starved for fuel. Got it back to shore eventually. Long story short, I bought a new fuel filter and replaced it and it fired right up. Stayed running the whole day, however still had the acceleration problem. I think the o-ring on the fuel filter was too big and wasn't seating properly, so it was sucking in air. Going to have the fuel pumps and engine checked again. Still at a loss over the poor acceleration.

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Just discovered that the duo props weren't aligned correctly. The front and back props were passing vertically directly underneath the cavitation plate. Looking online I've found that they should not do this, so I've taken the front prop off and realigned so they do not pass directly under the cavitation plate now. Taking the boat out, hopefully, this weekend to give it the old test. Not sure if the prop alignment will solve my issues, but it's worth checking it out.

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if it is still sluggish. take the props to a prop shop to be sure no one changed the pitch. one or both.

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ive read up on timing the blades. I dont think its going to do it. Merc on the B3 and volvo doesnt state doing this. Probably not bad to check. Personally I pull every plug and check them. Fill with some fresh gas and add some sea foam and go from there.

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Plugs CAN tell a lot about sick cylinders. The condition & color will be different if 1 or more cylinders are sick.

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Took the boat out for yet another test with the props aligned correctly. I do have to say it did make a difference, however slight, with having the props aligned correctly. Hole shot was ever so slightly faster and the only other noticable difference was pulling a tube; you didn't have to keep it wot in turns, just almost wot.

Here are the results of the original compression check that I had done on the engine when I first purchased it:

#2 145 psi #1 145 psi

#4 145 psi #3 145 psi

#6 145 psi #5 145 psi

#8 140 psi #7 140 psi

I can't find anything online that states what the psi on this engine should be, other than that the psi should all be within +-5 psi...

I think the next thing I will do is have the engine checked out again, by another boat mechanic and then if all else checks out, try a different set of props. As far as I can tell the pitch of the F5 props is almost a 23 and I was thinking of dropping down to the F3's that are approx. 19 pitch. Running at 1,100 feet elevation, this should help a lot with my hole-shot. My next dilemma is choosing a 3/4 prop combination or a 4/4 combination. Any thoughts?

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Seaweed build up ?

Fresh or saltwater running ?

Volvo paint inside the fuel system parts. Where else can they put it to make dealers the richest on the planet.

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I had a very similar boat. You should be turning 5k on the RPM`s. Perhaps cleaning the filter would help, but I might consider trying a new set of props in addition.

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You will lose about 3% of engine power for every 1000 ft of elevation. Assuming the engine is running correctly, and I think it is, you need to drop down in prop pitch. Your current RPM @ WOT is too low, and that will damage an engine over time. If you can, find a shop that will let you test an F4 or F3 to see what works best.

It is also possible that your boat has gained weight over the years. Consider removing anything you haven't used in the last year (other than safety/required gear). Make sure you don't have water trapped in the bilge.

I think a lower pitch propset is going to resolve your issue.

brick

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I have F4's on mine, but I'm at sea level and the acceleration to a plane is fine.

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I would check the speed with a hand held GPS meter. Have a mechanic clip on HIS rpm meter at the same time. Post the results. Might be a eye opener for all of us & the mechanic.

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Just wanted to update this older post as I still own the boat.  I eventually updated the duo prop set to a Quicksilver 3/4 combo 21 pitch.  After trying the props out, I did have some gain in holeshot, but not enough to my liking.  The Marine was willing to exchange the props and I dropped down to a 19 pitch.  What a world of difference.  I did lose a couple of mph on the top end, but I am okay with that as now I can actually pull skiers and wake boarders out of the water.  Tubing is vastly improved also.  I have had the engine serviced every year and everything always checks out fine, so I know there never was any problem there.  I would say though, if I ever have to replace the engine, I will opt for a larger, more horsepower engine as I feel the 5.0 is undersized for how big the boat is.
Side note: last season I did have to clean out the thermostat housing and replace the thermostat as it rusted 'closed'?? causing the engine to begin overheating (replacing the impeller and troubleshooting, led me to the thermostat).  Reading online, the vast majority of thermostats fail 'open' (I may have the terminology backwards), so the engine doesn't overheat, but I wasn't so lucky.  After a good scrubbing and complete cleaning, it is back to running cool as ever; I think it had the original thermostat from '03 still in it!

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The correct pitch props make a huge difference. What RPM do you hit now at WOT?

brick

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On ‎17‎/‎04‎/‎2018 at 11:19 PM, jamisond said:

Just wanted to update this older post as I still own the boat.  I eventually updated the duo prop set to a Quicksilver 3/4 combo 21 pitch.  After trying the props out, I did have some gain in holeshot, but not enough to my liking.  The Marine was willing to exchange the props and I dropped down to a 19 pitch.  What a world of difference.  I did lose a couple of mph on the top end, but I am okay with that as now I can actually pull skiers and wake boarders out of the water.  Tubing is vastly improved also.  I have had the engine serviced every year and everything always checks out fine, so I know there never was any problem there.  I would say though, if I ever have to replace the engine, I will opt for a larger, more horsepower engine as I feel the 5.0 is undersized for how big the boat is.
Side note: last season I did have to clean out the thermostat housing and replace the thermostat as it rusted 'closed'?? causing the engine to begin overheating (replacing the impeller and troubleshooting, led me to the thermostat).  Reading online, the vast majority of thermostats fail 'open' (I may have the terminology backwards), so the engine doesn't overheat, but I wasn't so lucky.  After a good scrubbing and complete cleaning, it is back to running cool as ever; I think it had the original thermostat from '03 still in it!

That is interesting!  Can you share the cost of the quicksilver props?  I have F5's on my set up and due to elevation think I would be happier to be geared lower, however the purchase price of Volvo props has me scared to try a different set off of ebay or something...

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I paid $1250 for the set, brand new. I did look for quite a while for a set off ebay, but went with the Quicksilver from the local shop because they had the exchange policy, which I ended up having to do.

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