Trim tabs 3.0 Merc.

[Grenkepr]

Hey guys,
I have a 1991 3.0 mercruiser with points ignition. Over the last 2 yrs. I have been fighting the same old problem. Engine runs fine for anywhere from 10 to 30 minutes. Sometimes when I go to trim the engine.the motor starts cutting out. Entire ign. system has been replaced, carb. rebuilt, new alt., new battery. Strange thing is, it will run forever with no problems when out of the water.This led me to the trim tab sensors on the outdrive. The wires are corroded and bare in some spots. I have tried cutting out the bad and resplicing with new. This did not help. Could this be the problem #1 ? If so how do I replace them? Is it possble for this to backfeed thru the ignition system ? If so ,could I just take the wire off of the trim gauge, to stop the backfeed. Thanks in advance for any help.

 

[Bondo]

Re: Trim tabs 3.0 Merc.

Could this be the problem #1 ?

Ayuh,... Somewhere between Nope,+ Shouldn't matter....
The Trim Pump is a totally independent system from the igntion system...

I'd suspect a severe Voltage drop... Probably from corroded wiring connections....

Those wires, if broken, only disrupt the Up trim button circuit....
Then you could just use the Trailer button which by-passes the limit switch...
To Replace 'em you pull the drive,+ the gimbel housing...

 

[JustJason]

Re: Trim tabs 3.0 Merc.

Run the boat like you normally would. Pull the engine cover off, put a mulitmeter on the coils + post and ground out the other end.

It should be reading 14 volts or so. Hit the trim button and see what the voltage drops to.