1988 4.3L Mercruiser losses power once it warms up

[jerzyski]

My '88 Sea Ray with a 4.3L 2bbl carburetor runs like a dream when it's cold and at cruising speed. Once it warms up or I give it full throttle it bogs, then losses RPM's and power. Then it heats up, starts to make a "tinging" noise and won't get up/stay up on plane. I've had a new ignition module/distributor cap/rotor installed. I also installed a new "anti syphon" valve, but no change. The water filter/separator and fuel filter are both clean/good. The engine seems to heat up when this happens.. Once I power down and the engine cools it runs good until it heats up again. What should I check/ change next?

 

[alldodge]

My '88 Sea Ray with a 4.3L 2bbl carburetor runs like a dream when it's cold and at cruising speed. Once it warms up or I give it full throttle it bogs, then losses RPM's and power. Then it heats up, starts to make a "tinging" noise and won't get up/stay up on plane. I've had a new ignition module/distributor cap/rotor installed. I also installed a new "anti syphon" valve, but no change. The water filter/separator and fuel filter are both clean/good. The engine seems to heat up when this happens.. Once I power down and the engine cools it runs good until it heats up again. What should I check/ change next?

Could be fuel but check your timing first with the tinging

 

[achris]

Had a similar problem many years ago on a 4.3... Turned out to be a bad ground on the dissy, put a wire from the dissy body to the engine block and that fixed it. As AD suggested, check the initial timing and advance when the engine is both cold and when it acting up.

http://www.boatfix.com/merc/bullet/95/95_11.PDF

Your curve is on page 9... The initial advance should be 8° at idle (650rpm), with total advance being 22° at 2500rpm.

Chris......

 

[Stamey]

I'd check the coil for thermal breakdown. This will likely entail replacing the coil to see if the problem gets better but you may be able to see a difference if you put a spark tester on it when cold then when the problem is occurring.

Chris

 

[Bondo]

My '88 Sea Ray with a 4.3L 2bbl carburetor runs like a dream when it's cold and at cruising speed. Once it warms up or I give it full throttle it bogs, then losses RPM's and power. Then it heats up, starts to make a "tinging" noise and won't get up/stay up on plane. I've had a new ignition module/distributor cap/rotor installed. I also installed a new "anti syphon" valve, but no change. The water filter/separator and fuel filter are both clean/good. The engine seems to heat up when this happens.. Once I power down and the engine cools it runs good until it heats up again. What should I check/ change next?

Ayuh,..... Welcome Aboard,..... The Color of the spark plugs,.....

I suspect yer carb is trashed, causin' a Lean condition,....
When that happens, Detonation is chewin' up the insides of the cylinders,...
Don't do it anymore, if it stutters, slow down,...
You'll "Hole" a piston or worse,....

It runnin' Ok cold, 'cause the choke is hidin' the symptoms,...

 

[jerzyski]

Thanks for the suggestions, I'll try starting at the least expensive approach until the issue is resolved.. BTW achris, what's a dissy?

 

[achris]

distributor.

 

[jerzyski]

Thanks,