need help with 1975 115 hp mercury power trim and tilt

[Gomer50]

Re: need help with 1975 115 hp mercury power trim and tilt

Try this wiring Diagram.. And yes has to be hot (12 volt) both red and white on the switchbox in order to fire.

 

[tbone1987]

Re: need help with 1975 115 hp mercury power trim and tilt

well guys i got pretty discouraged yesterday after i failed to hot wire this tower of power. not sure what im doing wrong. i am wondering if i have to hook the battery up directly to the harness. im just hooking it up to the battery terminals that you would normally hook it to. i tryed to jump it just like the diagram says. the side of the motor with to starter and harness. i hooked up a lead to the two bottom switches on the switchbox. should be red and yellow. now i tryed to hook the other lead to the red battery cable on the starter selinoid. i took the other end of this lead and touched it to the small clips on the starter selinoid. i tryed them both. should the lead be conected straight to the battery. now that im typeing this post im pretty sure it does. becase the ignition is still in front of the battery before it gets the power from the engine harness. my test light isnt lighting up on any thing. what should i do?????

 

[Chris1956]

Re: need help with 1975 115 hp mercury power trim and tilt

OK, The third wire from the bottom on the starboard side of the switchbox (your picture #2), is connected to a brown color plastic right? That is the tach sender, which should be unused. Disconnect it.

The wire below it is connected to the red plastic. This should always be +12VDC when the battery is connected. Jumper it to the wire below it, which is connected the the white plastic on the switchbox. This should power the ign and you should have spark.

Jumper from the battery cable on the starter solenoid (your picture #1) to the white wire, to cause the motor to crank.

 

[tbone1987]

Re: need help with 1975 115 hp mercury power trim and tilt

it seems like im doing the hotwire process right. i dont thing im getting power to mt switchbox. could it be bad? or could the wireing in the remote box for my ignotion make this happen? it looks like the engine harness did. completely shot. but its all hooked up.

 

[Chris1956]

Re: need help with 1975 115 hp mercury power trim and tilt

Check the wire on the red terminal. It must have +12VDC on it. Then you jumper that voltage to the white terminal, and the ign will work, if the trigger, coil, switchbox are all good.

 

[swamp-fox]

Re: need help with 1975 115 hp mercury power trim and tilt

If I was you I would wait an get a new key or ignition. If you are not sure of what you are doing, you run the risk of touching the wrong thing with the jumper wire and frying it. Those motor take a HOT battery to start, so make sure your battery is fully charged. In my experiance you have about a zero chance of pull starting it. I have pull started my 1977 90hp however it was running all day and still took anout a thousand pulls.

 

[tbone1987]

Re: need help with 1975 115 hp mercury power trim and tilt

ITS ALIVE!!!! thank you guys so much for your help. this thing didnt just fire up, it sounded absolutly amazing. i can just hear how much power this thing is going to have. i had to rip out the mess of wires in the battery compartment and straighten it all out. today i got the fuel tank cleaned out 2. i hooked it up to the muffs when i started it but it didnt pump water. gonna pick up an impeller tommarow when i grab the new ignition. i hope its juyst the impeller. next, after i got it to fire i did compression test..... not good. on cylinders 1-3 i had 120 psi. which is good. but cylinder 4,5, were at about 95. and i didnt get to check number 6 because i had to go get the kiddo from school. so what does this mean.? bad rings?if so is there any way to make it though the rest of the summer before a rebuild? i want to get the ignition in tommarow and take it for a water trial. see if the power is there. again, thanks to every1 that helped me get this beast wired up. couldnt have done it on my own. you guys rock

 

[douglas1978]

Re: need help with 1975 115 hp mercury power trim and tilt

you can prey to the merc gods and try to decarb it, this works about 5% of the time but on the lower psi cyl u can put a little oil in them and if the compression comes up its the rings

 

[tbone1987]

Re: need help with 1975 115 hp mercury power trim and tilt

bummer. thats not what i wanna hear. i have 1 other qustion i forgot to ask. my power tnt is only going down. i turned th knob on the pump and i can raise it by hand. but when i hit the up switch, it just clicks once and does nothig. bad pump? needs fluid? ive never messed with one of these pumps. thanks in advance fellas.

 

[douglas1978]

Re: need help with 1975 115 hp mercury power trim and tilt

might just be bad connections or a wire check the oil in it let us know. to bad you live down by peoria i'd help ya but i am 1 1/2 hours away

 

[tbone1987]

Re: need help with 1975 115 hp mercury power trim and tilt

well ive drove an hour and a half for far less important things. lol well im gonna give it another hard days work today and see what i can do with this thing. the ignition will be here at noon. ill get it wired up and see if i can fix the trim. i know this is a dumb question but what is a decarb exactly? how much does it cost to do a decarb? how hard is it to replace rings? do i do them all? bore the cylinders? suggestions???

 

[douglas1978]

Re: need help with 1975 115 hp mercury power trim and tilt

2 cycle engines leave a deposit of carbon i use a can of seafoam(12 dollars) in a 1 gal tank smoke pretty bad but cleans up the motor. if it is the rings and not a burnt piston you can replace the rings and hone the block won't know till you open it up but i would take 1 thing at a time and not get to far ahead of yourself, if you have a friend with another compression tester you can try a different 1 just to be sure

 

[tbone1987]

Re: need help with 1975 115 hp mercury power trim and tilt

ill give it another comp. test today. hope my tester is junk or i didnt have it on all the way or something. that sure would make for a good day. b ill post bck this afternoon with my results. thanks again doug. do you own a marine shop up there? i might need to take this thing somewhere eventually. the 2 shops i have local both suck. they've ordered me the wrong parts and gave me bad info twice. i have a few friends that are looking for a good mechanic also. of course i didnt reffer them to my local shops. like i said, an hour and a half isnt so bad of a drive to find a mecchanic with some integrity. someone that isnt gonna charge you an arm and leg for stuff you dont really even need. thats what you can expect from the 2 shops here in pekin il.

shipmans marine and gun:facepalm:
watkins marine :facepalm:

 

[douglas1978]

Re: need help with 1975 115 hp mercury power trim and tilt

just a backyard mechanic, jack of all trades a master of none. about 15 years ago i had an old 1955 rude needed carb work, did n't know my butt from a hole in the ground every place i took it to told me it was junk and i should just buy a new one found this guy down in chebanse,il(don't know if he's still there or not)he redid the carbs fix the choke put on a new clamp bracket changed the impeller an l/u oil and set me up with electric start i thought when he brought me the bill it would be huge. paid 125bucks he told me if you can turn a wrench you can fix anything you buy a manual research get the right tools and have the drive you can fix anything. there is alot of good people on this forum we are all here to help the fellow boater. i hope the compression comes up for you at least within 10% of the other cyl. so you can hit the water and enjoy your boat

 

[Chris1956]

Re: need help with 1975 115 hp mercury power trim and tilt

Tbone, if you have 95# compression in the lower three cylinders, the rings are likely good, as that would be an unusual circumstance for them to all be bad. Do the decarb and see what happens.

 

[merc850]

Re: need help with 1975 115 hp mercury power trim and tilt

I had a friend with a 200 that was down 20psi on one cylinder, he started running Amsoil synthetic oil at 50:1 and the pressure returned to normal. I run it too and my 850 is 150psi all around.

 

[tbone1987]

Re: need help with 1975 115 hp mercury power trim and tilt

ok, i got the new igntion. 2x bigger than the one i took out but hey, this isnt supposed to be easy right?the guys at my local marine shop just keep screwing me over. it should work tho. i can jam it in the control box if i can get it hooked up. well i think i got it hooked up right but i drained my battery and had to leave. i got switch to function. i have juice to my selinoid if i turn the key to "run". and the motor cranks if i turn to "start" but its not trying to fire. i broke my nuetral interlocking switch while i was stripping wires down and hooking it up. is this why it wasn't fireing?? just a thought. i figured it just kept motor from starting in gear but i dont really know much. or the switch isn't hooked up right?? the problem i had with the swith is i had a 5 wire switch before. and i got the same now. they had 2 wires piggy backed into another wire. and i dont have the same colors on my new switch. on my harness... theres 1 black, 1 red, 2 yellow, 2 white, and a brown. on my new switch.....theres a red, black, purple, black with yellow stripe, and yellow with red stripe. i have a key on the box the ignition came in that says what the colors are for. so my question is this......does any1 know what the colors of the wires in my harness are for? which 1s should i piggy back? the wires were falling to pieces in my control box so ts hard to tell what color used to be where. i know this is confuseing and a PITA:facepalm: . thanks for any help guys

 

[douglas1978]

Re: need help with 1975 115 hp mercury power trim and tilt

here's a link that should helphttp://www.maxrules.com/oldmercs/Wiring/1966ona/35.jpg

 

[tbone1987]

Re: need help with 1975 115 hp mercury power trim and tilt

thanks but this is the diagram i was trying to use today. it doesnt say what wires are for what, example: on the package of my new ignition it says the purple wire is for the ignition, black is for magneto ground, and so on.... but i dont know what the wires on my harness are for??? also, is my neutral switch i broke gonna effect the spark and keep it from fireing???

 

[douglas1978]

Re: need help with 1975 115 hp mercury power trim and tilt

save the diagram as a picture rotate it to make it easier to read its all there , the switchbox is on the front of the motor mine is colored coated like i said b4 if ya lived by me i would be at your garage with a case of beer and tools.