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2001 mercury 150 hp optimax engine revs at inital start up

boloseng

New member
"i have two 150 merc outboard

"i have two 150 merc outboard on my boat, engine A starts fine, when you try to start engine B, engine A revs up. wiring is correct, new isolator, no map sensor, new tps, did compression test, spark test, ohms reading is good on coils. i have been troubleshooting these engines for the past 2 weeks, i am running out of ideas. please help!!!"
 
"Do you have the SmartCraft ga

"Do you have the SmartCraft gauges and Merc's (fly by wire) rigging?

Just to be clear you get engine (A) running and when you hit the starter for engine (B), your "running" engine revs up?"
 
"i have the smartcraft gauges,

"i have the smartcraft gauges, i master reset them also. and yes the running engine revs up when you try to start the non running engine"
 
HMMM. All I can think is you a

HMMM. All I can think is you are sending 12 volts to the wrong place when you twist the key. Maybe into a 5 volt circuit somehow. That would probably have to be into the data wires for the S/C tach's. Or the S/C sensor power leads.

This is going to be tough to sort out. 150's don't use DTS so the engines should not normally be wired together to talk. This is a liability.

Is there a spaghetti mess behind the dash? There may be a short somewhere.
 
"yes behind the dash is a mess

"yes behind the dash is a mess, well thank you for the advice, ill keep you posted of my journey to find the source of the problem."
 
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