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boat wont start in water but starts in driveway


nagy24's Avatar
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05-26-08, 05:24 PM   #1  
boat wont start in water but starts in driveway

We recently bought a 95 maxum in/out with a mercruiser 3.0. The boat starts fine at home with the ear muffs but wont start when we launch it in the bay. The boat just had the upper unit and carb rebuilt with all new fluids in october '07 by professional mechanic and tested fine in the shop. It hasnt been run in the water since then..until we tried to put it in this weekend. The engine turns over but it just wont run in the water. We dont have a problem at home with ear muffs as we have tried it time and time again with no problem. We fiddled with the choke and made sure the tank is full of gas but still no luck. Its jut so odd that it works without flaw out of the water but as soon as we put it in the water, no such luck. This is boggling our minds. Any ideas what might be the cause??

 
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thezster's Avatar
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05-27-08, 08:24 AM   #2  
If she hasn't been in the water since your professional mechanic worked on it... then it's his job to make it work.

Your issue makes no sense... though I don't doubt it is occurring.

 
CrownlinePilot's Avatar
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06-04-08, 11:02 AM   #3  
If it starts out of water I would just crank it up on the ramp before I back down and then see if it keeps running once it hits the water. May have something to do with the intake sucking in water causing it flood since it hasn't been in the water in so long.

 
chedester's Avatar
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06-04-08, 01:33 PM   #4  
I'm not too familiar with your boat model. Some boats have a sensor to determine the amount of water in the cooling system so you don't burn it up. It may be an obstruction (plastic bag, piece of trash, magnolia leaf) has found its way into the water intake. The muffs are pushing past it with the high water pressure from the house, but the impeller may not do it well enough. Also, if the boat has been run aground in sand frequently, the impeller in the water pump may not move much water. If there is a sensor looking at flow through the cooling system, it would shut down for lack of water. If you don't know if the boat has been sucking sand, look at the prop and the bottom of the boat. If they show signs of deep massage from 80 grit sandpaper, it's likely.

 
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06-06-08, 03:49 AM   #5  
Definately a safety switch or sensor problem, the manual should make some mention of this anomaly, most mercruiser manuals are very detailed and I am sure it is going to be something simple, please post back your find.

 
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06-07-08, 09:25 AM   #6  
Hi guys, the 1995 3.0 mercruiser did not have any kind of
flow sensor that you would find like on an efi engine.
What it may have is a shift assist switch that momentarily
cuts the ignition to aid in pulling the gears back to neutral.
If the boat has been sitting a while the shift cable
gets sticky and will cause intermittent spark failure.
To check this, look at the shift levers on the engine.
Follow the two black control cables to where they meet.
Usually on the rocker cover, or on the exhaust manifold.
You will see a small switch with a roller on it.
It sould be positioned in the " notch " for running.
If it is hung up on the high side. Jiggle the control
handle to release it.
My guess is you are pumping the throttle at the ramp
and this switch is getting activated. try it and tell
us how you do. scott

 
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06-09-08, 09:37 AM   #7  
Resolution

Hi everyone,

Thanks for all of your suggestions and willingness to help! We tried a few things and looked into some parts that you all suggested and it didnt appear to be anything along those lines. We ended up taking it back to the mechanic the originally did the work on the carb in order for them to take a look at it. He said they did a thorough check of their previous work and all other running parts of the boat and all they could find was a faulty starter. Turns out, they think the starter was just on its way out and when we put the boat in the water, maybe their was just too much backpressure and the starter just couldnt work hard enough to get it going... I think thats the gist of what they were saying.. Who knows. Either way, we put the boat in the water this weekend and it started right up with no problem. Although, about 5 minutes into running, we stopped to hang out for a bit, put the boat in nuetral and it stalled out. We almost couldnt get it restarted and it was like dejavu all over again, but with a few attempts and finally putting it to full throttle it started up again. After that, we ran the boat for several hours with no problems at all... maybe the boat just needed warmed up??? Not sure.. we're going to call the mechanic back and tell him what happened and see what he says. Hopfeully when we take out again this weekend, we wont have any problems at all this time.
Just wanted to give everyone an update and let ya'll know how it all turned out.

 
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06-10-08, 12:54 AM   #8  
i suggest taking a can of starting fluid with you so if it stalls out again spray some into the airfilter on the engine to get it going again.

 
westnlas's Avatar
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06-10-08, 05:15 AM   #9  
westnlas

Although I am sure the ideas you've already gotten are probably the solutions. I would take a close look at the bilge area and make sure there is no grounding of any electrical when water accumulates there. Sometimes, especially with boats, the answer to a problem is something so simple, no one thinks of it.
A friend had his inboard towed to dock because of a loose coil wire.
Good luck.

 
thezster's Avatar
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06-10-08, 06:44 AM   #10  
carrying starting fluid is probably not a bad idea... at this point... Sounds to me as if you're on the right track - get that mechanic involved again... Your carburation, be it the choke system, and/or the idle mixture screws, and/or the idle speed setting - is the culprit. Doncha just love fiddlin with boats????

 
nagy24's Avatar
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06-11-08, 08:57 AM   #11  
This is our first boat, and we finally found out the meaning of the word "BOAT" Bring On Another Thousand. LOL

 
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06-12-08, 03:37 AM   #12  
The starter must have been drawing more amps than usual and not allowing the coil to deliver enough hot spark for starting? I think this needs to be looked into further, there may be some ignition problems

 
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06-12-08, 07:35 AM   #13  
Posted By: nagy24 This is our first boat, and we finally found out the meaning of the word "BOAT" Bring On Another Thousand. LOL
A boat is a hole in the water into which you throw money... Have fun!!

 
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06-20-08, 01:31 PM   #14  
i HAD THE SAME THING

I had the same happen after working on distributor. I adjusted the ignition timing in the driveway and everything worked great. Then i took the boat to the lake and couldn't get it to start. Luckily i had all the tools with me so i hooked the timing light and readjusted the timing. It was way off. After that ran like a champ.
The way i figure, because you change exhaust preasure by putting your stern 2 feet under water your timing changes too.

Hope it helps.

 
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