Sudden power loss with prop. or something else??

[primative]

I have a 99 , 22'CD cruiser. I bought it as a new demo., in 99 at Sportcraft Marina in Portland. It came with a new 1997 Honda 90.The prop.it came with is a mercury 13 1/4 diam. x 17pitch.They said this size was best and the next size being the 13 1/2 x 15 (Honda) would be too much of a work prop.( low speed with high rpm). Over the next few years I used the boat primarily for day/weekend trips, and the perfomance seemed acceptable, but was less so when heavily loaded for extended type trip.Meaning boat would have difficulty planing and could not develop adequate rpms.

So I called 3 to 4 c-dory dealers from WA. to Florida, and they all said, OH, you should be using the 13 !/2 x 15 that the motor standardly comes with, and thats what we all have best results with.I was told I would have rpms nearer to 6ooo at wide open, as compared to the low/mid 5000's I was used to with the original.

In July, 04, I put on the 13 1/2 x 15, and man does it feel responsive(getting up on plane easier, and better control at the low end speeds which I feel the boat is best suited forl). Unfortunately, when I run the boat at higher rpms( last incidince, above 5200-5400) for 5-10 minutes it suddenly loses power with simultaneous alarm beep for a second or two. I noticed brief flash of the red light last time, but not neccessarily in previous episodes. I originally thought it may be a fuel starve problem, but now I wonder if it is a cavitation problem at the higher rpms, though I do not sense any slipping of the prop.

This may be a seperate problem/s, but I've added some recent repair history that may be useful.

Sport Craft changed my water pump Sept. 03 , because of a history of abrupt power loss episodes developing in a two week camping trip, using boat every day, progressing to alarm with red light coming on.

In june 04 while towing skiers, developed loss of power. The boat would power back up again normally,and lose power again, until idling a bit. Initially it didn't cut out before about 4000 rpm, then progressed to cutting out around 28oo, (the alarm-red light never came on during this episode) and we just didn't try planing any more to get back to the dock.
Took it in to Sport Craft to check it out. They said" fuel good, thermostat operation ok, changed plugs just because, and river tested twice without any problem, and don't have any ideas/solutions to try further", if its not showing problem.

Fellow dorymen if there are some obvious answers I sure would appreciate it! If not, I would like your recommendation for a mechanic on this problem. Sport Craft has treated me well, but I may need a second opinion. No one can be expected to have a solution all the time.

Thanks,
Tom and Rene, the Primative

[Helen O]

Fuel filter?

[Larry H]

Tom and Rene,

Overloading the motor with a prop pitched too high or with a heavy load ( or skiers)can cause an overheat/slowdown from high rpms.

A fuel system restriction can cause a similar thing. The motor gradually 'starves' for fuel until the carb bowls run low or dry. The motor abruptly slows down until the fuel pump catches up with the carbs.

What does your owners manual say about the alarms? What does the red light or warning horn mean?

Your motor may have an automatic slowdown protection circuit to protect the powerhead from overheat/low oil pressure. Your owners manual should tell all.

[primative]

Larry S. and Larry of the Nancy H thanks for responses. I took the hint on checking the manual for light/buzzer indications. I think I'll need to take the boat out again and try to reproduce the shut down and get more certain what light I'm seeing or not, with buzzer or not. Actually it states the buzzer would always sound in either case of low oil press. or overheat. I'm thinking its best to to get the problem to repeat before trying to go any further. We're getting some arctic air and predictions of snow this week, hope I can get out. I have a particularly steep set of roads near my home, so we will see.

tom

[primative]

Took her out 1-6-05.
I produced the problem by running at or near w.o.t., 6000~5500 rpm, and doing zig-zag pattern path. Motor abruptly slows down to idle with simultaneous alarm and red light, indicating overheating, for a second or two. I could then resume normal operation. Oil pressure light never went off, indicating no loss of oil press..

So it would seem the S-turns produce cavitation related overheating, due to changing angles of the prop as I banked side to side, Right?

The anti-ventilation plate is approx. 1" below my hull.

Has anyone else experienced this? What to do?
-Tom

[Captains Cat]

Tom, very strange. What does the telltale do during these times? That's the cooling water that comes out of the underside starboard side of the engine. If it's continuous, then I'd suspect a sensor problem. If not, it may be a water pump problem (impeller or the like), although that should manifest itself at other times too.

You said the thermostat was OK, that also should show up at other times if it's sticking. Sounds lilke a sensor to me. But then what do I know....I'm the one that takes stuff apart to fix it, puts it back together (sometimes) and am surprised when it works again. I even set the family record player on fire when I was a kid when I hooked my crystal set to the phono pickup to try to amplify my signal. Whooooooeeeeeee

Charlie

[Captains Cat]

Meant to mention, I don't think "overheating" would happen that quickly, even with a loss of cooling during cavitation. Check that telltale...

[stevej]

Tom how's it going?

Overheating is not something that comes and goes in a few seconds. Start with getting a tech manual and id the location of the sensor/sensors check the connection and wire path frist. Maybe a bad sensor or wire rubbed through.
Give me a call be happy to assist.

stevej

[primative]

Charlie,

thanks for the the responses. You had me there for a moment with the term,"telltale", and fortunately you explained it. I've been using the technical term "peewater" for so long I didn't know what you were talking about.

It pees good, I mean well, that is, the telltale is fine, I think all the time. From what you've said, and Steve J's response, I'll be checking the sensor.

Charlie I'm glad you're the kind of guy who takes stuff apart, because now with good telltale I'm not thinking prostate gland.

Steve, thanks for your input about the technical manual... good idea. It's a must for me. I'm relieved to have some leads to follow here.

Tom

[Captains Cat]

Hmmm. Got me to thinking, maybe it's my sensor, not my pump. Tried it last night about 3AM and sure enough, when I put my hand in a bowl of warm water, the pump worked fine...



Good luck, let us know what the outcome is...

Charlie

[drjohn71a]

Tom...... Having had a similar problem in both cars, trucks, inboard boats and outboards.... some sort of fuel restriction situation should be considered, be it fuel filter or kink in the supply hose somewhere... I would rule that type of thing out before taking too much apart. I did have one, two engine jet boat that had either a bad sensor or a short in the sensor since which ever engine we installed that sensor on - that was the one that beeped and lit up.

btw...you guys are alot of fun to read! John

[primative]

Dr.John, thanks for reply. Too busy to check sensor yet. Going to Seattle Boat Show and mostly hang with dory people for fun and land adventure.

Now for a surprise. My wife Rene and I are both from McPherson Ks.

Gotta stay on schedule and will get back to you.

Tom

[drjohn71a]

Tom , Wow, that is close! I bought fish to stock a pond on my old house years ago from Mc Pherson. I work in Wichita, but live on a farm just East of Harper , KS which is about as far SW of Wichita as Mc Pherson is North of Wichita. I wish I could be at the Seattle Boat show - maybe another year. Although I started the note discussing fuel restriction, it does sound to me exactly like that defective sensor I had on that jet boat. It would go off right after a load, turn, etc.. Good luck on the boat problem. John

[AK Angler]

Well, I don't know about the "overheat" alarm, but I don't think it would overheat and cool off just doing S-turns.

As far as the intermittent motor shut-down goes, it sure sounds like a fuel issue. Maybe water in the tank? I had a similar problem last fall. I would be cruising along and the motor would just kick back to idle all of a sudden. Then it would roar back to life for no aparrant reason. After much hair pulling, I finally traced it to a leaking fuel cap. Turns out there was about a quart... yes, a quart.... of water in the gas tank.

[drjohn71a]

I did not mean that the engine actually overheated.... on the contrary... the alarm kept going off, but the engine never actually overheated.

Water in the fuel, or some junk in the fuel filter ... likely if slower onset...

anxious now to see what the problem really turns out to be! john