115 merc from late 70's

[grasshoppertym]

just bought a 1976 (i think) crysler conqueror 135 with a 115 merc from the same era. i heard that i have to run high test fuel is this true? i also heard that i might have to run a lead additive is this true?

i can't wait to get it on the water but i need to get the trim tilt working better first, it has gone up and down sometimes but the next time it just clicks. i have changed out the capaciters so i know that isn't the problem and i have checked all the fuses and cleaned all the terminals i can reach. i guess i will just need to get someone to hold the trim button while i wiggle the wires around and hope to find a bad connection somewhere.

anybody that can help me out on the fuel questions would be great and it would take a few things off my mind.

thanks, Mike

 

[Chris1956]

Re: 115 merc from late 70's

Mike, Regular gas is just fine, provided the max timing is set to 21*BTDC. No lead substitutes are necessary. Mix fuel to get a 50::1 gas oil ratio.

The PTT has no fuses, that I can recall. The PTT pump has one or two solenoids. Make sure the black wire form the motor is grounded to the PTT housing. Clean all connections. Remember, for Trim up power needs to be +12VDC on the blue wire, ground on the black wire. For down, you need +12VDC on the green wire and ground on the black wire.

The purple wire in the PTT harness is for the trim Limit switch. I usually bypass them since they tend to break.