Engine won't run in the water

sailingMel

Cadet
Joined
Aug 22, 2010
Messages
18
I have a 1983 Evinrude 115. It runs great with the water ears on, sitting on the hard. It idles good and sounds like it has lots of power at high RPM's. When I put it in the water, it starts really hard and will not idle. The only differance is being in the water with the exhaust underwater. Could the back pressure from being in the water effect the ability for it to run right? Any ideas would be very helpfull.
 

oldcatamount

Lieutenant Commander
Joined
Apr 4, 2010
Messages
1,740
Re: Engine won't run in the water

It's definetly the exhaust pressure when the lower unit is submerged. Sounds like you may have the carbs adjusted a little too lean. Try adjusting the carbs giving her more fuel.
 

Daviet

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Sep 24, 2008
Messages
8,958
Re: Engine won't run in the water

If your idle is set to low it will cause your type of problem. You should set you idle to about 650-700 RPM in gear with the boat in the water.
 

sailingMel

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Aug 22, 2010
Messages
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Re: Engine won't run in the water

Good info so far, I did turn up the idle but maybe not emough. I am not sure where the fuel mixture adjustment screw is. Should I turn it in, or out to gain more fuel to the mixture?
 

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: Engine won't run in the water

There is no fuel mixture screw.

You should do a compression test and a spark test to be sure that you have all cylinders firing. You cannot tell on muffs - it can sound fine running on two cylinders.
 

Daviet

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Re: Engine won't run in the water

You did not list your model number, the parts breakdown that I looked at shows you do not have any adjustments on your carb, it has fixed jets.
 

sailingMel

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Aug 22, 2010
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Re: Engine won't run in the water

So, with no adjustments on the carb, how do I get it to run more rich to increase the power. Should I take the carbs apart and clean them? Do I have to get kits for them to do that, or can I just carefully take it apart and re-use the parts? The numbers on the engine are: Model # 115999R
Serial # J0007263
I have checked spark and it's good, the coil packs are new, fuel lines are new, spark plugs are new as well.
 

mrcj001

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Jul 25, 2008
Messages
313
Re: Engine won't run in the water

Like Ezeke said, check the compression on all cylinders. They all should be within 10% of each other.

If you have 115lbs on 3 cylinders and one is 90 lbs, its not enough to get the engine to run smoothly.
 

mrcj001

Petty Officer 1st Class
Joined
Jul 25, 2008
Messages
313
Re: Engine won't run in the water

So, with no adjustments on the carb, how do I get it to run more rich to increase the power. Should I take the carbs apart and clean them? Do I have to get kits for them to do that, or can I just carefully take it apart and re-use the parts? The numbers on the engine are: Model # 115999R
Serial # J0007263
I have checked spark and it's good, the coil packs are new, fuel lines are new, spark plugs are new as well.

If the engine is new to you, I would install new kits.


It never hurts to check and clean the carburators, but I myself would check the compression of the cylinders. If compression is bad ,carb cleaning wont help.
 

sailingMel

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Aug 22, 2010
Messages
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Re: Engine won't run in the water

Here are the compression readings...#1= 98 #2 = 102 #3= 89 #4 = 82
Are these compressoin readings close to what they should be? I also need a manual. Can you recomend the best one to buy and where to get it? I plan to remove the carbs later today too and see what they look like inside. My next plan is to put the lower end in a large tub of water to recreate the back pressure of it being in the water to see how it runs. Any suggestions will be greatly appreciated.
 

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: Engine won't run in the water

I suspect from those numbers that you have a lot of carbon build-up in your engine, and that de-carbon treatment is overdue. You may want to do that now and take new readings afterwards. Follow Captain Dunkelberger's original methods in the Engine FAQ for best results: http://forums.iboats.com/showthread.php?t=158076

The best sevice manuals are factory ones. You can get new reprints from the publisher here: http://forums.iboats.com/showthread.php?t=158076
Used and surplus copies often appear on EBay.
 

sailingMel

Cadet
Joined
Aug 22, 2010
Messages
18
Re: Engine won't run in the water

I did the decarb...worked great. NOw my compression is 124, 125, 110, 110. Marked improvement! I tore down the carbs and found the jets to be nearly clogged. I put it all back together and fired it up and after about 3 minutes of running the water stream quit, so now I'm off to get a new waterpump impeller kit. Thank you all for the great input.
 
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