83 50hp still wont throttle up

PepinMatt01

Recruit
Joined
May 29, 2010
Messages
4
I have a 1983 Mercury 50hp 4 cyl 2 stroke, on a 16ft Lund. I've had no problems with this motor for 20 years. Last year it began not opening up past half throttle.It starts, idles and trolls just fine. First i replaced fuel tank line,bulb, fuel lines to carbs,and sparkplugs. Didn't help. I then checked compression, all four at 115-120. When i checked spark i found one dead coil. I replaced that and one plug wire. Still no go. I took it to a dealer, they said stator was bad. I replaced the stator myself with a CDI #174-5454k1, didn't help. Someone on this forum suggested that the stator maybe defective. So i replaced it with another CDI stator and Trigger, no change. Frustrated i took it to another dealer, told him where i was at on it and asked him to rebuild the carbs, thinking it was fuel, not electrical. Three weeks later and 732.00 dollars, he called and said the carbs were done, and it still would not open up. He chewed me out for putting CDI parts on, and said his mechanic had spent a hour with a CDI tech by phone trouble shooting. He told me that the new stator was also bad. He wanted to replace it, but i was pretty unhappy with his service, and brought the boat home. I put the out board in a stock tank and checked voltage with a DMM while running. At idle the blue and blue white wires started at 150 volts, as i throttled up, the voltage went from 140 to 122? The red and red white wires were at 50 volts in neutral and 36to 132 as i throttled up. Any recommendations? Thanks
 

Hawkeye22

Recruit
Joined
May 5, 2010
Messages
1
Re: 83 50hp still wont throttle up

Sorry to hear about your problems with the mechanic, they obviously didn't run the proper tests and wanted to guess what they thought was wrong. I actually have the same motor and have been recently been going through what you have in troubleshooting, at least you have new parts in the engine. Since the coils tested o.k. and you have a new trigger and stator, I imagine the only thing that is not properly working would have to be the switchbox.
 
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