1979 115 hp 115999R Evinrude Outboard runs great in test tank at fast & slow idle, does not in when I put in the water

MikeG2021

Cadet
Joined
Jul 23, 2021
Messages
12
Hi,
I have been trying to get this motor running right for months.
I took it to two mechanics. The first, a reputable Marine shop, that had it for three weeks, and it came back running worse than it did when I took it in. The second, an old boat guy near me, that only works on old boats. He had it for another four weeks, called me when I was out of town, said it was running good, and wanted to drop it off, and would come by to go over what he had done when I got back. He did, said it was running fine in his boat yard. It was raining that day, so we did not test it to see if it ran. Fast forward a few weeks, had good weather, decided to take it out, didn't test it in the drive way, cuz he said it ran, got to the bay, it did not. brought it home and called him. he came by a 2nd time, said something may have clogged the carbs confused as he had just rebuilt them. He said something could have come up from the bottom of the tank.. Told me to buy a fuel/water separator/filter, and to call him after i installed it. I did, he never came back. So following advise from others on another forum, I started going through things myself.
To summarize: I tore the carbs all the way down and soaked them in cleaner for 24 hours, rinsed them and cleaned them again, then rebuilt them, new carb kit, new low idle orifices, ( these on this modle as not adjustable, they are fixed and screwed all the way in.), new gaskets, floats and all. made sure the linkage was synced, replaced all the hoses from the new fuel/water separator to the carbs, replaced the fuel pump, replaced the thermostats, and the plugs. put it in the test tank, it fired right up in fast idle, and kept running when I locked in down into low idle. (Just to mention, I went through the carbs 3-4 times before tearing them all the way down this last time. ) with it running this last time, i took it down to the bay for a test. It started right up, let it warm up for a few minutes, dropped it down into low idle and it kept running! YAY!!! Finally!!! NOT!!!!
it slowed and died out as it has done every other time I put it in the water.
Tried it a few more times, then brought it back home. Put it back in the test tank to clear the salt water out of it, started right up and kept running.
I have not checked the compression or the spark, as i figured the way it runs in the tank, that must be OK.
I know I have to be close, but I have no idea where to go from here.
I have been trying to find an original service manual, but the one or two I have found seem to be way over priced. it is an service manual, not a rare manuscript!
I am beyond frustrated!
Any advice from y'all would be fantastic.
Thanks in advance!
Mike
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,606
Some will argue.-----A compression test is step #1 on a V-4 crossflow.----Post your numbers.----Note----It only sounds good to the untrained ears in your test tank.----Sorry for the blunt statements.
 

MikeG2021

Cadet
Joined
Jul 23, 2021
Messages
12
Some will argue.-----A compression test is step #1 on a V-4 crossflow.----Post your numbers.----Note----It only sounds good to the untrained ears in your test tank.----Sorry for the blunt statements.
OK, looking at the back of the motor, the two cylinders on the left are at 79 PSI, the two on the right are right between 78-79 PSI. What does this tell us?
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,606
You have a bad test gauge or a motor that needs rebuilding.----Remove the wee bypass covers on the side of the motor ( 6 screws each ) and look at pistons and rings.----Lucky you if it is just blown head gaskets.
 

MikeG2021

Cadet
Joined
Jul 23, 2021
Messages
12
You have a bad test gauge or a motor that needs rebuilding.----Remove the wee bypass covers on the side of the motor ( 6 screws each ) and look at pistons and rings.----Lucky you if it is just blown head gaskets.
its a brand new guage. but i will admit this is the first time in my life i have ever done this test. i followed the instructions those were the results. i can run them again to be sure. not sure where or what the bypass covers are.
I think i figured out the covers there are four one for each cylinder. right?
What am i looking for when i pull them?
 
Last edited:

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,606
Damage to pistons and rings.-----Post pictures of pistons and rings when you look in there.----You did confirm that starter / battery and battery cables are in good condition ?----In my opinion this should be easy to diagnose !
 

MikeG2021

Cadet
Joined
Jul 23, 2021
Messages
12
Damage to pistons and rings.-----Post pictures of pistons and rings when you look in there.----You did confirm that starter / battery and battery cables are in good condition ?----In my opinion this should be easy to diagnose !
starter battery and cables are good.
I'm going to test compression again, then i will pull covers and send pics.
just retested the compression and realized i misread the gauge the first time, all four are between 95-100 psi. so am i good to not look at the pistons?
 
Last edited:

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,612
You have water or debris in you tank (guessing it's a built in tank). A shop runs with its own gas for control purposes. Run with a portable tank and fresh fuel. You may have to clean the carbs again.
 

MikeG2021

Cadet
Joined
Jul 23, 2021
Messages
12
not sure what to look at from here.

I am going to drain, pull and inspect the tank, lines and anything else, yes it is built in.
I also put on a fuel water separator where the fuel line comes out of the hull to the motor.
but why would it run in the test tank and not when in the water? its the same gas coming from the same source?
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,612
carb is probably clogged, or water killing power. (in a glass jar, btw, water will be visible at the bottom if present)
 

MikeG2021

Cadet
Joined
Jul 23, 2021
Messages
12
Would it not also be visible in the clear bowl at the bottom of the fuel water separator if there was water in the fuel?
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,612
"I have not checked the compression or the spark, as i figured the way it runs in the tank, that must be OK." You need to check both. On the water contamination, any running you did before installation of the filter would potentially have contaminated the carb.
 

MikeG2021

Cadet
Joined
Jul 23, 2021
Messages
12
I completely disassembled and rebuilt the carbs after I installed the external filter. along with every this else I have replaced or checked.
That said there was a little water in the bottom of the bowl on this filter.
So it's doing it's job.
I'll pull the tank and check it and replace all of those lines.
 
Top