MerCruiser Power Problems

T

tsal

Cadet
Joined
Jun 6, 2002
Messages
8
Hi all,<br /><br />I have a 1989 4.3 Alpha 1 Mercruiser. It starts OK, and idles OK, but after about 30 minutes, the high speed RPM drops to about 2,500. I can idle down, but when I try to throttle up it coughs and pops out of the exhaust. If I remain at idle for 20 minutes or so, or shut it down for the same amount of time, then my top end is back. Any ideas would be appreciated - I think it's fuel related, my brother feels it is electrical...
 
W

wavskipper

Cadet
Joined
Jun 20, 2002
Messages
8
Re: MerCruiser Power Problems

Does it heat up significantly ? Could be a lot of carbon on the heads inhibiting your "burn" of the fuel . Don't think electrical would cause this.
 
T

tsal

Cadet
Joined
Jun 6, 2002
Messages
8
Re: MerCruiser Power Problems

Nope, it's not heating up too much; Probably about 120-140F
 
T

trevorcday

Petty Officer 1st Class
Joined
Dec 2, 2001
Messages
216
Re: MerCruiser Power Problems

I just fixed a 5.0L mercruiser with similar symptoms. It turned out to be the ignition sensor inside the distributor cap. This motor had the Mercury Thunderbolt IV electronic ignition.
 
T

tsal

Cadet
Joined
Jun 6, 2002
Messages
8
Re: MerCruiser Power Problems

Thanks, I'll check that out; is there a way of testing this?
 
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