BOAT DOES NOT RUN IN THE WATER WHY!!!!

[xtremestang]

This boat is driving me crazy please help have replaced intake manifold, exhaust mainfolds, head gaskets in this 1988 Imperial with a gmc 350 and a mercruiser Alpha 1. This boat runs fine out of the water but once its in the water it stalls out and wont start again until taken out of the water WHY???????

 

[Don S]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

Sounds like water in the gas tank and no fuel/water seperator installed, or it's full of water.
When on the trailer and the bow of the boat is down the fuel pickup in the tank sees gas. When in the water with the stern of the boat is lower in the water than the bow, and the back of the gas tank is lower. Since water sinks to the bottom of the tank, that's what the pickup in the tank feeds the carb. WATER.

 

[dodge1971340]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

Hi Stang!! Is i hard to start when you get it out spit and spudder or does it fire right up and run smooth? and did this do the same thing before you changed all that stuff or did it start after? Dodge

 

[xtremestang]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

Hi Stang!! Is i hard to start when you get it out spit and spudder or does it fire right up and run smooth? and did this do the same thing before you changed all that stuff or did it start after? Dodge

It starts right up when it is out of the water it did not do this before all the things were changed

 

[xtremestang]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

Would broken exhaust shutters cause this problem?

 

[Don S]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

No exhaust shutters won't cause your problem. Did you read my first reply ? ? ? ? ? ?

 

[xtremestang]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

Ok replaced the fuel filter and water seperator. Boat starts fine out of the water.. Put it in the water wont start just keeps cranking does not turn over. Pull it out again starts right up. Backed the boat down the ramp on trailer until stern is in the water , wont start. Still on the ramp pulled stern out of water, Starts right up.

 

[wire knot]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

I'll take a shot at it.

Could be a ground wire that is shorted by the water, out of the water no path to gnd. Check the Ig. wiring.

Sounded like water to me too.
Try running on a spare tank to eliminate the water in tank question.

 

[dodge1971340]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

HI again Stang. I was going to say the same thing as Wire Knot ground wire short. Something is shorting out. when in the water see if its getting spark when you turn it over. if its not its in the wireing somewere, try this when its in the water take the ground off to the drive housing from the motor and try to start if it starts its prob a ground short somewere. Let me know what you find!! Dodge

 

[bruceb58]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

You need to do a little more troubleshooting when you are in the water.

First off, see if you have spark. Although I don't really believe things are shorting out, I guess anything is possible.

Second, see if you have fuel.

Have you done any of these tests yet?

 

[kdmiller8251]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

Yeah do more trouble shooting, veryify spark etc. and if you have all that hook up a spare tank. Sure sounds like fuel to me.

T

 

[kbetts]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

Check the wires to your trim senders on the outdrive, sounds like they might be bare wires and shorting out when they hit the water.

 

[bruceb58]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

That would not cause this problem.

Check the wires to your trim senders on the outdrive, sounds like they might be bare wires and shorting out when they hit the water.

 

[dodge1971340]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

If it was water guys wouldnt it spit and spudder run ruff!! he said i fires right up and runs fine when he takes out of water. But i agree with all of you he needs to do some more troubleshooting. 8) Dodge

 

[crawdadric]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

What about your idle speed adjustment. Let’s say for example, you adjusted your idle speed to 650/700 on land with muffs and now when you place the boat in the water, the backpressure created from the water covering your exhaust ports makes it impossible to start. On my boat, the idle is set to 650 in water and on land the tach reads around 1100 RPM. Just a thought...

 

[marunr]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

What about your idle speed adjustment. Let’s say for example, you adjusted your idle speed to 650/700 on land with muffs and now when you place the boat in the water, the backpressure created from the water covering your exhaust ports makes it impossible to start. On my boat, the idle is set to 650 in water and on land the tach reads around 1100 RPM. Just a thought...

I've never heard this before. Are you sure?

 

[cobra 3.0]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

No that doesn't make sense. You can increase the idle speed just by moving the gas lever forward in neutral at start up. I need to always give a bit of gas on start up with mine or it won't start.

 

[Pst76]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

Just a thought, Put the outdrive in the water just below the intake for the raw water cool. MInimize any chance of restriction on the exhaust.Start the motor and back boat into the water running, see if it stalls.Maybe its not breathing. (Dont, let run very long with out outdrive in the water for cooling.)Have seen carboned up exhaust on an outboard run great on muffs but drop it in the water and just enough added restiction that it would stall out.
Also if on the trailer and it run. Tilt trailer bow down and up and see if angle that tank sits makes a difference. I would think water in gas would create problem in or out of water. I'm just throwin out idea's so may be way off but anything is possible, There Boats....

 

[xtremestang]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

Have already tried the starting out of the water then putting it in the water real quick it will run for a few minutes then stall then will not start again until taken out of the water. Starts right up. I think I have the solution I have the first boat that is allergic to WATER.
Seriously Im thinking this has to be an electrical problem but where do I start. With ground wires????

 

[calwldlif]

Re: BOAT DOES NOT RUN IN THE WATER WHY!!!!

What prompted the manifold changes?
And head gaskets?
New boat to you?
In all the responses there is good advice.
Time to check idle settings and chase wires.
Post more hard info, general stalls and won't start
stuff isn't narrowing the prob.