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Old 03 May 2015, 17:07   #1
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First Time out with the Zodiac, Major Problems with the Engine...

I just took my boat (and engine) out for the first time today. There seems to be a major malfunction with the drive system, at least that is my best guess. The engine didn't have much difficulty starting up at first launch, however it soon quit on me out of nowhere on the middle of Pistakee Lake. It kept quitting on me throughout the day, forcing me to restart it time and time again. But back to the story, after some finaggling I was able to get it restarted, and putted along back into port. The gentleman who ran the boat rental shop was kind enough to come take a quick look, his opinion was that the engine itself was running okay, so I decided to try topping off the buoyancy tubes and keep with air, thinking that may be the issue. I had called a Zodiac dealer to get his thoughts, that was his best suggestion.

It did not really solve the problem. My first suspicion there may be a problem was the high speed sound of the prop whirring/chopping through a mixture of air and water at full throttle, as if there was a major cavitation or ventilation problem. Though, ventilation is unlikely, seeing as how the boat is designed for a short shaft motor and the keel/tubes were verified to correct pressure by my Bravo pump. The starter motor was also acting up on me quite a bit throughout the day.

As I continued my test of the boat, I found that full throttle would produce enough thrust to raise the bow, but not actually get up onto plane and speed. The best I can describe is that I was getting 1/4th the amount of thrust I should've been at full throttle 80% of the time, and a rev to 7000rpm and very quick planing out 20% of the time. In essence, I was either going 6mph or 20mph at full throttle depending on what the motor was doing at that time. The tach is set to 4P, as per Mercury specs, I had a Mercury on the phone with me as I set up the tach. The prop chopping/whirring noise could be from it overspeeding in the water, turning too fast. The strange thing though is that the RPM at full throttle setting was seemingly correct when (getting way too little thrust from the motor), at around 5200rpm. Only when I finally started getting some power did it jump way up to 7000RPM.

Just as an aside: Fuel was automobile gas, with 50:1 oil mix of Quicksilver Premium Plus, along with one ounce each of Mercury Quickcare, Quickleen, and Quickstor. Fuel line is equipped with Attwood fuel demand valve (this is a factory pre-assembled Mercury fuel line). Also, I am not sure if there is a thermometer-metered water cooler, but the pee stream varied from a halfway decent stream to just kind of a dribble. If there is a thermometer, I would like it yanked out, not seeing a decent stream is disconcerting. I can turn the prop by hand in the same direction the prop would be turning in forward gear, while it is in forward gear. It makes significant audible (and felt) clicks when turned. I cannot turn the prop by hand either direction when gear selector is in reverse. Not sure if that's relevant information, but the Zodiac dealer I was able to get a hold of had me do that as an on-water inspection and said it was his assertion i shouldn't be able to turn it at all by hand in gear.

I took a video, which I uploaded to YouTube, to show the problems I was having. The link is below.



Please let me know what you think about what is going on with this motor... It's still under warranty from the shop I bought it from, they will apparently cover any costs for repair of defects 90 days on from first use.

https://scontent-ord.xx.fbcdn.net/hp...36&oe=55DBC5F5

https://scontent-ord.xx.fbcdn.net/hp...9c&oe=55D9D52F
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Old 03 May 2015, 17:47   #2
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Could be allsorts of things. Prop slipping on hub, gear linkage not adjusted correctly so the gearbox isn't properly in gear ( not good if you've been hitting 7000rpm ) This might also account for the repeated stalling if the engine has a shift assist/start in neutral protection. Don't mess about posting on here, get it back to where you bought it from asap before your 90 days is up.
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Old 03 May 2015, 17:53   #3
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Quote:
Originally Posted by Pikey Dave View Post
Could be allsorts of things. Prop slipping on hub, gear linkage not adjusted correctly so the gearbox isn't properly in gear ( not good if you've been hitting 7000rpm ) This might also account for the repeated stalling if the engine has a shift assist/start in neutral protection. Don't mess about posting on here, get it back to where you bought it from asap before your 90 days is up.
I had someone tell me that from the YouTube video, they thought my tach was off. Though it's set properly, I checked what setting it was supposed to be at from multiple sources including Mercury.

I've already emailed the shop my explanation and the video. The process to get everything fixed is in motion. The thing that still scares me is the noise I heard coming from the prop, I hope it's just from the fact it was overrevving and not an inherent problem I have with my boat/engine setup. I had my Bravo manometer inflator aboard to make sure all the tubes and keel were topped off at 3.5psi.
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Old 03 May 2015, 17:56   #4
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Does the speed of the boat increase when the engine over revs?


Love the name of the lake BTW
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Old 03 May 2015, 18:18   #5
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Hi all

I would be trying a different tach .No way is that reving to 7000 RPM.Possible fuel starvation issue Or electrics.
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Old 03 May 2015, 18:25   #6
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Spun hub sounds plausible and a problem with the shift mech.... Possibly it has hit something before causing what you describe?

Probably also needs carb looked at.

It doesn't sound like it is hitting 7k in the video to me but I wouldn't use it again until your shop verifies it.

Cheers
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Old 03 May 2015, 18:43   #7
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Originally Posted by Pikey Dave View Post
Does the speed of the boat increase when the engine over revs?

Love the name of the lake BTW
There is a MASSIVE difference in thrust, and thus speed, when the RPM decides to go up when my throttle is at full. The bow rises, but doesn't go to plane, when the indicated RPM is at the usual 5100. When it spikes to 7000+ (as indicated), i get an almost scary amount of power.

Quote:
Originally Posted by dubrus View Post
Spun hub sounds plausible and a problem with the shift mech.... Possibly it has hit something before causing what you describe?

Probably also needs carb looked at.

It doesn't sound like it is hitting 7k in the video to me but I wouldn't use it again until your shop verifies it.

Cheers
People keep telling me the tach is off, but I'm not sure how that could be the case. I have it set to what Mercury instructed, which is 4P, and it's a Mercury brand tach. Though I agree it doesnt *sound* like it was overrevving, but I'll just take the entire lot (tach, fuel tank, and all) to a different shop.

The engine has never hit anything that I am aware of, I had these problems from the get-go of using it. I am the only owner of the engine since being purchased after rebuilding.
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Old 03 May 2015, 19:01   #8
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You did open the vent on the fuel tank didn't you?
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Old 03 May 2015, 19:05   #9
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You did open the vent on the fuel tank didn't you?
There is no vent on my tank. As of a few years ago, all fuel tanks sold in the US must be anti-venting as per EPA regulations. There's an automatic vaccum valve on the cap though to let air in if there's a negative pressure gradient, it just wont vent air out. I also have an Attwood fuel demand valve in the line to prevent an overpressure of fuel to the motor.
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Old 03 May 2015, 19:09   #10
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Ok. Had a similar issue before and was because I forgot to open the vent lol. Have you checked the cap is working correctly as if it is not replacing the used fuel space with air it will create a vacuum and cause pretty much what you are experiencing.

Could you run it with the cap loose to see if it works
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