www.iFourWinns.com

Anyone else have a 348 Vista with inboards and Teleflex electronic throttles? Mine is not allowing me to push the engines up to full RPMs (5000). It's topping out at 4000. I can rev them in neutral but not while under way. I'm guessing some sort of adjustment is probably in order but figured it's worth asking first.

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-Bill Kearney, 2005 348 Vista

Where did you come up with the 5000 for max RPMs? I had the same question on my boat when I first bought it and questioned the dealer. The mechanic pulled out a card and I was getting right what he had on the card. In my case with the 8.1L I think it was more like 4200 or so. I'll try to find out where I saw that chart showing all the max RPM for the engines and if I find it I'll post it. Wouldn't prop size make a difference as to what RPM you are able to turn?

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2008 Vista 278 Volvo Penta 8.1 Gi 375 hp
1999 Horizon 220 5.7 GSi

As part of a discussion with FW last year. The inboards aren't quite as fast as the outdrives and I questioned why. Not reaching 5k would be one reason, and certainly a factor this year. That and when new the boat would top out at 5k and nothing's been changed to the props or anything else related. The question isn't whether 5k is appropriate, the question is what's keeping them from getting there. These are electronically controlled throttles, where the controller is reading RPM from the fuel injected engines. They're both topping out at the same point further leading me to suspect it's an engine controller issue. Were there a difference between the engines then I'd have different questions.

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-Bill Kearney, 2005 348 Vista

Bill, I'd bet if the throttles allow 5k in neutral then it's not a throttle issue. Usually not reaching max RPM at WOT means drag. Maybe the bottom is dirty? I have teleflex controls on my Volvo sterndrives.

BTW I don't think the speed difference between sterndrives and inboards has to do with max RPM. From what I've read, it's more to do with drag from the underwater gear and the misdirected power because the props are pointed slightly down.

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2008 V358 Two-tone Blue V/P Dual Prop 320 HP
Lake Winnipesaukee, NH

That is a good explanation. It's not an RPM issue at all as far as performance issues are concerned.
The weight of inboards centered deep in the hull of a boat improves stability because they lower the boat’s center of gravity. The drag created from the propshafts, rudders , struts and their position on the hull, contributes to the lower performance level as compared to sterndrives.

The outdrive positioning in the far back of the boat (as opposed to further forward like inboards) helps improve the performance.

I suspect as jrcinnh does your issue is drag related. Also when you tangled with the crab pots, your props may have not been pitched like they were originally. Dirty bottom, crud or something currently tangled in the running gear are drag possibilities as well.

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One of 4 Previous (Sold) Boats:
2000 Four Winns 268 Vista

Current Boat: 2004 Chaparral 235 ssi cuddy

The reason I had asked my dealer about the max RPMs was because I was not getting them. I can't recall exactly buy my top RPMs dropped by 300 or more because my hull was fouled. When I pulled the boat to go in for service I cleaned the hull and my RPM went back to where it should be.

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2008 Vista 278 Volvo Penta 8.1 Gi 375 hp
1999 Horizon 220 5.7 GSi

And I never indicated it was. It's typical for an inboard drive vessel to be somewhat slower than it's equivalent with outdrives. I'll trade top end over outdrive maintenance any day of the week. By how much was the question. Regardless, that's unrelated to the issue at hand. As is anything related to past problems with crab pots. When put up for storage it would make 5k and it's top speed. Everything related to the propulsion was in full working order and alignment. The props were replaced (and known to doing their job as expected). Nothing has changed since besides time and sitting in the water. And I'm not getting any uneven operation from the engines.

Yeah, I'm expecting some slowness due to fouling. But not this much. I ran a brush along the hull and was pleasantly surprised how little had grown. And when dealing with fouling last Spring it was more a matter of top speed, not max engine RPMs. The growth was worse then too. I could make 5k revolutions just not it's full top speed. Now I can make neither.

I'm going to pull the fuel filters and replace them.

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-Bill Kearney, 2005 348 Vista

Ok let leave the sterndrive vs inboard for later.

I don't think the controls know if you are in gear or not, so I'd guess they throttles got to WOT while under way if they go to WOT while in neutral. Too bad you can't be in the engine room to see them. Is there something else that points you towards the controls?

If your previously well set-up boat can no longer make max rpm at WOT, its usually either loss of power or drag. You ruled out drag, that leaves power. Fuel systems are a good place to start. Did you recently change sources of fuel, or change to E10? How is the cooling, do the temps look right? Partially blocked cooling might cause overheating and the engine computer might limit power, but thats unlikely to hit both engines at once. I guess next would be ignition, again unlikely to hit both engines at once but it has to be something. How long since you changed the plugs? Are your batteries charged? Low voltage to the engines can cause weak spark and loss of power, but it would have to be really low.

Back on drag, are you carrying more weight than last year? Full tanks, extra passengers? Have you checked that your trim tabs work? If they got stuck all the way down, it would cause a lot of drag.

That's all the guesses I got. Sorry for the shotgun delivery, I'm sure you already checked all this stuff.

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2008 V358 Two-tone Blue V/P Dual Prop 320 HP
Lake Winnipesaukee, NH

Amen to that. Having owned both types in the past, I will never purchase another IO again (unless it doesn't sit in a slip all year).

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Current Boat: 2000 Four Winns 298 Vista
Previous Boat: 2000 Carver 406MY

My vote is that it's more than likely a fuel related issue. Fuel pump, fuel quality, fuel filter, fuel pressure. Did you just get some bad/old gas? Too much stabil?

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2008 318 Vista -SOLD, but I am still around!
All Night Long, Seattle WA

Bill does the teleflex system sync the drives?

Yes, it can sync the drives. But they're both only climbing to 4k individually, and obviously the same when sync is used. The engines each pull from their own tank. The gas is from last season and there is some stabil in there. But I've not had that be a problem after past winters. It's not entirely the 'same' gas in both sides as one was filled unevenly due to the generator also pulling from it (the port side).

My next step will be to replace the filters and then run the existing tanks down a bit.

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-Bill Kearney, 2005 348 Vista

yea.. I was curious how often guys are changing the filters and water separators. For me, I just spent 200 bucks on all the filters! Sucks, but with the ethanol I'll be doing this every season... Three water separators (one for the genny) and two, two piece cartridge filters for the mercs. Do you guys really free - rev these old school pushrod motors to redline!?!?

Honestly I haven't changed mine the past two seasons. So I guess I'm due. Just plain forgot them.


Free rev, as in when in neutral? No. And not often during regular running, at least not on a regular basis. Mainly because the fuel burn rate is hideously expensive. But in a few situations it's useful, like being able to get the hell out of the channel leaving the Severn from Annapolis. When up on plane I'm pretty much making as much wake at 21 as I will at 35. But at 35 it'll take less time to get clear of the ragbaggers trying to tack back and forth all over the place. Better to crank it up, get clear and then settle back to the usual 3,500 rpm cruise. That and I won't have to see their dirty looks and frantically waving fists and fingers for as long. They so hate powerboats... until they need to be towed out from somewhere...

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-Bill Kearney, 2005 348 Vista

I have never rev'ed the engines in neutral, I've never even put the drives in neutral. I do run the engines at WOT about once a year. Last fall I hit 42 MPH (GPS) the needle did not cross the 5000 mark on the tach. But I don't have a lot of confidence in accuracy of the tachs on my boat. Mostly I cruise at between 3500-4000 RPM.

Since I block my boat every year for winter storage, I don't find the sterndrive maintainance costs to be very high. I wet slip in fresh water and a money I save on fuel covers the drive service. This is my 9th season with a sterndrive boat.

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2008 V358 Two-tone Blue V/P Dual Prop 320 HP
Lake Winnipesaukee, NH