Merc 228 problems

[HanlonsRazor]

Ok so I will be detailed as I can.

I have an 82 Glastron SSV 196 with a mercruiser 228 in it. So far I have replaced the water separator, rebuilt the carb and changed the coil. My distributor is not a points but has an ignitor in it. Also have brand new mechanical choke that is working. So I take the boat throw it in the water on the trailer and start testing the engine. Engine idles great, water pump works good boat shifts In to forward and reverse with no problems.

Now the boat had sat for about a year with 17 gallons of gas in it and I had filled it with about 7gallons of fresh and also some seafoam, it did however run on the old stuff. Unhooking the throttle cable from the lever ( so I'm not engaging the prop)
I take the engine all the way to about 3800 rpm and hold it there for about 2 min with no problems. Engine is rated for 4600 max so i figured the 3800 i had it at would be ok as a test run. Temp all this time is 160F. After doing this i put the engine in gear at idle and let the prop turn and see how it does.

All this is done on trailer with boat sitting in the river. Prop turns fine I give it a little gas and it shoves it self up on the trailer farther with no problems. I then put the shifter to neutral and engine to idle. And yes the momentary delay that kills the engine while you come out of gear works. About 30 min has passed now and then the engine gets a slight miss to it. nothing major but then i start to loose my idle rpms (idle was between 800 to 1000 out of gear.) then the engine dies.

Restart engine and try to give the boat throttle by using shifter and engine dies every time. Go back to engine un hook throttle cable and restart engine. Engine runs for about 2 min then dies. Restart again only this time i slowly give it throttle with my hand on the main lever at the carb engine does take the throttle (yes the choke is working like its supposed to.) but i can only get to about 2000 rpms now any thing over that and it bogs then dies. Also as i restart the engine it gets harder for the starter to turn it over. I know its not out of time and it started just fine when i first put the boat in the water. I think the started maybe rotated the engine twice if that before it ran.

This is the 2nd time this exact thing has happened the only difference being that i had put a new coil in and a new fuel water separator. Part of me wants to say this could be fuel pump but why would it run up to 3800 and then run for so long before dying?

Thank you in advance for your time and consideration.

 

[NHGuy]

Start inspecting your parts. Inspect plugs for color etc, White = water washed or lean, tan = normal, etc. Check diz cap contacts.

I bet you are getting water in the engine through the exhaust tract. Spin the engine over with plugs removed and check for water in combustion chambers. If you find water when you spin the engine, remove the risers neatly. You are looking for water tracks between the cooling water tract and the exhaust, (inward). Also look down into the exhaust manifold to see if there's any water laying in there.

If there's water in the combustion chambers but the riser gaskets look good, it could be time to check your risers and exh manifolds for internal leaks. There's a sticky at the top of the forum with instructions.

There's also a chance that if you had that water issue, there could be engine problems created by the presence of water. So a compression test will tell you how things are. You'll have the plugs out so do that too.

If you find water in the combustion chambers get em oiled with some WD40 to stop rust.

 

[NHGuy]

Here's another really unlikely scenario. If that engine has a hot cam, like something from a perfomance car, it could suck water back at lower rpms. Trailer use can exacerbate this if the boat is held at a wrong angle to the water and too deep in the water. Not likely, but possible.
Read up on reversion if there's no visible cause for your problem.

 

[Bondo]

Now the boat had sat for about a year with 17 gallons of gas in it and I had filled it with about 7gallons of fresh and also some seafoam,

Ayuh,.... My guess is, ya got 17 gallons of junk in the tank,.....

Which is now all through out the fuel delivery system,.....

 

[HanlonsRazor]

Thanks guy and bondo, just took it out today and noticed a leak in the starboard manifold that I did not see before. Guess ill break that one off and see if I can weld it or buy a new one.