runs like poop!

[hotmerc]

i'll try to make a long story short, lol... have a 88 carver santego with twin 98' 4.3 vortecs. had a water intrusion on port motor. had no compression on starboard side head. dismantled and found bad head gasket and the head was toast. got a reman mercruiser head and new gasket, risers, manifolds, plugs, wires, cap, rotor,changed oil about 5 times to get all the water out. put back together and timed. had it running really well, to the point were it scared me, lol. ran it at the dock for about 30 minutes for a couple of days, then ventured off to sea. it ran great going out and coming back in. but when i reduced power before going back to dock it was running like it had a miss, then stalled. it would start up but stall right after. took off engine cover and tried to start the next day and the butterfly for the choke was rapidly opening and closing, like i was getting some back pressure somewhere. still has miss. going to do another compression check. anything else i might look at?

thanks guys...

 

[Don S]

Re: runs like poop!

Your compression test will tell you the story. Or at least which cylinder it is. A leakdown test will tell you what it is exactly.

 

[JustJason]

Re: runs like poop!

the butterfly for the choke was rapidly opening and closing

If you have an electric choke, Pull the cover off and make sure the spring is not broken. Then set the choke correctly and veryify that it's getting voltage when running.

 

[hotmerc]

Re: runs like poop!

i do have an electric choke. its a 2 wire so i would assume it should get 12 volts. i'll check the spring coil. that would be great if thats all it was. thinking about swapping carbs if compression checks out okay.

 

[Don S]

Re: runs like poop!

Faulty choke adjustment is not the cause of the choke plate flapping back and forth. That is caused by a bad valve. You need the compression test.

 

[hotmerc]

Re: runs like poop!

i think i know what the problem is, and i havent done compression check yet, its raining, lol. about 3 days after having this problem i tried to start and heard a banging noise in the valve cover in the head i just replaced. i'm thinking the exhaust valve for the number 2 cylinder is stuck and from the push rod going up and down vibrated the nut off that holds the rocker on. i did replace the nut but it still runs like its got a stuck valve. will do compression check, but thinking that will be my problem. i'll take valve cover off and check the rod to make sures its still straight. i'll rap the exhaust valve with a 10 lb. hammer to free it up, dump some oil on it and let it soak. if that doesnt do it i'll take off the head and have it redone.