4.3 Idles great no power under a load

stopher8

Cadet
Joined
Apr 15, 2015
Messages
25
I have 1994 Bryant 180 with a 4.3 Mercruiser. I just bought it in April and have yet to have a successful outting with it. First trip out the water intake hose came off and about melted everything. Two cracked heads, I replaced with reman and felpro gaskets. Next trip engine ran great, found both trim hoses melted and leaking. They were doing fine in the driveway. Oversight on my part, replaced hoses. Third trip out boat ran great. WOT around 5k and sounded good. Choppy water around 48 mph according to the speedo. On the way to the dock running about 35 or so it just peetered out and died. Spun and spun but not start finally I held the throttle wide open while cranking and it fired up. Put it in gear and it struggles. The only way I could start was hold it wide open. The ignition has been "converted" from the Thunderbolt to the Delco EST. I found a used but "good" coil and distributor from a Volvo and installed the ignition module and coil. Engine fires up great now. Just hit the key and she pops right off. But no power under a load. In the water I can give it full throttle and it barely reaches 2k rpm and sounds a bit rough. Pull it out of gear and rev it and its great. What am I missing????
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,301
my guess is that you have crap that ended up in the carb or the anti-siphon valve is partially plugged.

it only takes drops of fuel to get the motor to high RPM's with no load in neutral. however when you have a load, it takes gallons of fuel.
 

stopher8

Cadet
Joined
Apr 15, 2015
Messages
25
What's the anti siphon valve! I've read a few other posts about the fuel pump. This one is an electric mounted to the head near the fuel filter, which I did change.
 

stopher8

Cadet
Joined
Apr 15, 2015
Messages
25
Update...I found wires #3 and #5 crossed. I swapped them last night and reset the timing. Starts well and sounds good, although it did before too. I'm going to the lake tonight to check it out. I'd say that'll fix it.
 
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