Only starts out of water - Inline 6 1150

[tlewick1]

I bought this project boat a few years ago— the engine was seized due to being underwater and full of mud. I sort of rebuilt the engine and got it running again. It’s always been hard to start though.

This year, I’ll get the boat running easily out of water with muffs on, but when I take it to the boat ramp, it doesn’t start. This happened twice. The first time I went to the boat ramp, it seemed like I flooded the engine. Took it home and it still wouldn’t start with muffs on. Later that day when I was checking for spark, it started up with the muffs on. Went back to the boat ramp and wouldn’t start again. The second time, I tried not choking. It almost started up, but then seemed to flood again.

Compression on all the cylinders is 120. This season I tried cleaning out the carbs— making sure everything’s working there, and tried resyncing them again. The idle screws were open more than the Seloc manual suggests. When I put the carbs back on, I put the idle screws two full turns away from being closed and thought I’d adjust them in the water under load.

The only electrical component that hasn’t been replaced is the distributor. I thought maybe the trigger was acting goofy—- but once it started up again while checking for spark, I started thinking it had to do with the idle screws being off.

i read an earlier post where someone said something about the difference between cylinder compression and crankcase compression. I checked the cylinder compression. Not sure what the difference is though.

 

[Chris1956]

OK distributor ignition puts the motor at 1979 1/2 or older.

The motor was seized and you "sorta" of rebuilt the motor. What exactly did you do?

Sunk motors in freshwater need to be oiled and run immediately after carbs and distributor are cleaned and dried, for 45 minutes to dry them out.

Sunk motors in saltwater need to be torn down and cleaned, oiled and prayed over.

Initial carb setting (clean carbs) is 1-1/2 turns open. It should run in the water with that carb setting. Idle pickup timing is 4-6* BTDC. Max spark advance is 21* BTDC.

 

[racerone]

Low crankcase compression leads to hard starting in water.------Reason is------ crankcase is nothing but an air pump that has to overcome water pressure in order to get fuel into the cylinders.

 

[tlewick1]

“Sort of rebuilt,” meaning— I completely took it apart, replaced the pistons rings and some bearings, replaced all the gaskets, rebuilt the fuel pump, got all new nozzles for carb (and new floats)... eventually the CDI went bad so I got a new one. The new one went bad so I replaced the wiring harnesses and got another CDI.

How do you test the crankcase compression? Put it in a test tank with all the cylinders plugged and check for compression as usual?

It runs good when it’s running. A lot of power. A few times last year it died suddenly. Replaced the fuel thinking there was probably water there.

 

[tlewick1]

I originally timed it to 6* BTDC but to stop it from stalling under load, I pushed it up a little more.

 

[jimmbo]

There really is no non-engineering test for crankcase compression.

6* BTDC? As for what? Primary Pick Up Timing? or idle speed? There is no timing spec for Idle Speed. The Primary Pickup spec should have the engine running well above idle speed

 

[tlewick1]

I thought primary pickup and idle speed were the same thing. I’ll look into that. Thanks.

 

[racerone]

Idle timing is not something you " SET "------ it is the point where throttle plates start to open.--------Actual timing at idle lookas after itself.

 

[tlewick1]

I made sure the primary pickup was at 6* BTDC. I wish it wasn’t so hard to get going on the cold start. Anytime the engine is trimmed up for trailering, it’s hard to get the right fuel-air mixture once trimmed down and starting for the first time. I prime it till the bulb is hard and use the cold start throttle advance along with the choke. Seems like it takes a good 10-15 seconds to get enough fuel in to start kicking. And if it doesn’t start after then, it’ll flood. Sometimes starter fluid is the only way to get it started.

 

[Chris1956]

They are hard to start when cold. The nature of the beast. In addition to what you are doing, make sure the choke plates close fully when the choke is activated. Sometimes that bind in the plastic carb covers, and sometimes the carb covers can be too loose. Make sure the battery is full and the wiring is clean and tight. She must crank fast to achieve choke. Lastly, don't worry about flooding her. It is really really hard to do that when the motor is cold.

Hold the choke down, cold start lever all the way up, and crank her until she fires.

 

[racerone]

Install an OMC / BRP primer solenoid valve. -----A modern replacement for choke flappers on the MERCURY motors.-------It will make hard starting a thing of the past.-----Easy to do in my opinion.

 

[jimmbo]

They are hard to start when cold. The nature of the beast.

My 115 must have been defective then. Due to the fact I was too cheap to replace a weak Battery I had to rope start it. On a cold Start, it would almost always catch on the second pull.

 

[racerone]

No such thing as a motor in good condition that is " hard to start " when cold.--------It is the " nature of the beast " that is turning the key and using the wrong procedure to start motors..