witts end 4.3 merc - no power under load

[shelikesit]

1990 Mercruiser 4.3 262 Carbed Engine Thunderbolt IV Ignition - boat recently sat for 18 months<br /><br />Just explained to the wife what happened yesterday on the water and her reply was to post it here verbatim. She's tired of seeing me going bald from a full head of hair 3 weeks ago<br /><br />Problem - runs great here on the trailer, actually runs and starts so well it's scary - it idles, shifts and starts up and turns off fine. Got to the dock yesterday and it did the same thing, ran fine. About a mile up the river it bogged down and died and took 2 minutes to start back up. Gas tank is CLEAN and fresh.<br /><br />After this foul-up and for the rest of the day it took forever to restart, and it would die upon entering neutral. As long as I was in gear it was fine, as soon as I brought it to neutral it dies.<br /><br />Also it would not run with the 2 hoses connected to the spark arrestor, it would when I disconnected them, and they poured out smoke. I could tell a couple plugs had fouled from what seemed like too rich of gas.<br /><br />I think the carb is flooding and the choke is sticking on or vice versa. Coming home it seemed like the choke was just stuck on until I removed the tubes coming from the valve covers.<br /><br />Can someone give me some STEPS to follow to see if it's the carb or fuel pump. The fuel pump seems to work fine but it also seems as though it has to work double time when restarting. The carb seems fine until you put it under power or turn the boat off and try to restart, or go into neutral from under power.<br /><br />Can anyone make anything of this? So far the boats been kept away from a shop and I would like to try and keep it that way. You can bet if I went out there right now on this new day and fired it, the engine would turn right over within a second. Problem then would show a couple fouled plugs but with changing to new ones it would be fine until I hit the river..................... deceiving is all I can make of it..............<br /><br />Thank You

 

[rodbolt]

Re: witts end 4.3 merc - no power under load

sounds like your fighting several issues, most related to non maint. the gas in the tank may be fresh but what does the inside of the carb look like? is the choke actually opening? the two hoses are just crankcase vents and should not affect engine operation unless there is an incredible amount of piston blowby. the stalling when returning to neutral sounds like a sticking shift cable/slide assy keeping the shift cutout switch engaged to long. if you suspect its flooding remove the flame arrester,have your trusty eye protection and fire extinguisher handy and look down the airhorn while its running at idle, if you see any fuel from the bowl vent or venturi cluster its flooding, if not I would suspect a possible lean condition under load.<br /> but now its time to test the spark and compression to rule out some ign problems and cylinder sealing problems before moving on to the next set of tests.<br /> next time it stall returning to neutral look at the cutout switch and insure it has returned to the center position. if it remains triggered it kills the ignition making a restart impossible.

 

[shelikesit]

Re: witts end 4.3 merc - no power under load

OK will do on the switch, but restarting isn't impossible, it restarts but you can have dinner ready while waiting for it.<br /><br />Thank you for the reply, I'll get a compression tester and go from there.<br /><br />Yes, there is fuel sitting in the hole while looking in while it's running.<br /><br />Question - The carb sat for a long long time but I was told it was new before the sit. Is it worth rebuilding or get a new one.

 

[Bondo]

Re: witts end 4.3 merc - no power under load

Question - The carb sat for a long long time but was I told it was new before the sit. Is it worth rebuilding or get a new one.<br />

Rebuild It,.....<br />It's Probably just got Alot of Crap In It........

 

[shelikesit]

Re: witts end 4.3 merc - no power under load

Thanks Bondo and Rodbot, ya'll plus DonS and a few more have quite a following.<br /><br />If you ever make it down here and "the boat is running" be sure to call for your free fishing trip. By free, I mean everything, leave your wallets at the hotel.

 

[Weirdwalt]

Re: witts end 4.3 merc - no power under load

Watch out guys, he probably has a 'cleaning crew' at the hotel.

 

[bandit86]

Re: witts end 4.3 merc - no power under load

some older carbs had fuel filters right in the carb where the fuel line went in,