First time starting after sitting for years.

DJ_Allatoona

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Feb 24, 2008
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186
I just bought a used motor. Mercury 75hp made in 1986. Dude says it was sitting on a junk boat in his neighbor's backyard for at least 5 years that he knows of, likely many more. When I picked it up, we did a compression test, 130-ish on every cylinder and the starter seems capable. It turned over nicely using a jumper on a battery. Good spark on all wires via a tester. Carbs look good & clean to the eye. It was not connected to a remote or hose, and the gearcase is shot so we didn't try to start it. We did shoot oil into the plug holes before the compression test.

I don't know the condition of the fuel pump or the guts of the carburetors.

I still have to do the T/T wiring and un-seize a very stuck steering cable that was cut off on the starboard side. But I'm close to turning the key for the first time.

This is new for me. What should I do besides use a fresh battery and good fresh fuel? I never had to use starting spray on any motor before. Should I get a can beforehand just in case?

What are the odds it just starts up and purrs like a kitten? I'm very eager to do it, but it's still a few days away.
 

The Force power

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I just bought a used motor. Mercury 75hp made in 1986. Dude says it was sitting on a junk boat in his neighbor's backyard for at least 5 years that he knows of, likely many more. When I picked it up, we did a compression test, 130-ish on every cylinder and the starter seems capable. It turned over nicely using a jumper on a battery. Good spark on all wires via a tester. Carbs look good & clean to the eye. It was not connected to a remote or hose, and the gearcase is shot so we didn't try to start it. We did shoot oil into the plug holes before the compression test.

I don't know the condition of the fuel pump or the guts of the carburetors.

I still have to do the T/T wiring and un-seize a very stuck steering cable that was cut off on the starboard side. But I'm close to turning the key for the first time.

This is new for me. What should I do besides use a fresh battery and good fresh fuel? I never had to use starting spray on any motor before. Should I get a can beforehand just in case?

What are the odds it just starts up and purrs like a kitten? I'm very eager to do it, but it's still a few days away.

IF you squired oil in the the cylinders before you did a compression test; those reading are no good!!
you can get a 120 psi reading with all rings broken

What kind of "starting spray" are you planning on using?

if you can't contain yourself to start it lol then remove the LU and shove a garden hose onto the pickup-tube and start it.
it going to be LOUD
DO NOT REV. motor check if cooling passages are open.
 
Last edited:

flyingscott

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Apr 8, 2014
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7,985
2 spray bottles filled with a 25-1 mix and spray that directly into the carbs for the first start. Do not do anything else until you know the motor runs. Watch the peehole and make sure water comes out. After that another compression test, if that is good then rebuild/clean the carbs, fuel pump and replace the fuel lines. Then replace lower unit.
 

DJ_Allatoona

Petty Officer 2nd Class
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Feb 24, 2008
Messages
186
IF you squired oil in the the cylinders before you did a compression test; those reading are no good!!
you can get a 120 psi reading with all rings broken

Well. Hm. I wasn't aware of that. I'm clearly an idiot.

And I'm going to install my good lower unit before I start it for the first time, and it will be in the water on my trailer.

Now I'm thinking about that oil/compression test thing. I just thought it was the smart thing to do, given the number of years it had sat without being run.
 

The Force power

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Well. Hm. I wasn't aware of that. I'm clearly an idiot.

And I'm going to install my good lower unit before I start it for the first time, and it will be in the water on my trailer.

Now I'm thinking about that oil/compression test thing. I just thought it was the smart thing to do, given the number of years it had sat without being run.

NO, you're NOT an idiot!

You did the right thing to squirt oil in before you started cranking over the engine to lubricate the cylinder walls.
You may want to try to de-carbon the rings/pistons also, with product such as sea foam (don't expect wonders)

When you want to use a "starting fluid" do NOT use brake-cleaner/ ether !! they remove all needed lubricants !!
use WD40 or such/ pre-mixed fuel in squirt-bottle

in my opinion............I would try to get it running before you install the LU, just in case the motor is a dot.
When the motor is up and running timed/tuned right, then check the compression.
 

DJ_Allatoona

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2 spray bottles filled with a 25-1 mix and spray that directly into the carbs for the first start.

Thanks. I have read that gas mix is better than any of the canned Prestone or Valvoline starter fluids. I've just never done it before. Do I hold that springed 'flap' open with my finger and shoot some of the mix into the carb? And how much? Say, if it was a Windex bottle, how many pumps?
 

flyingscott

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Apr 8, 2014
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Open the throttle all the way and squirt a couple shots into each carb. The close throttle and start the motor once it fires just spray into the carbs it should stay running. I just use dollar store squirt bottles?
 

The Force power

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Thanks. I have read that gas mix is better than any of the canned Prestone or Valvoline starter fluids. I've just never done it before. Do I hold that springed 'flap' open with my finger and shoot some of the mix into the carb? And how much? Say, if it was a Windex bottle, how many pumps?

There's also a handy Sticky on the top of the Mercury forum labeled "how to start a 2-stoke" this may come in handy

https://forums.iboats.com/forum/eng...er-outboards/10156881-starting-a-2-cycle-merc
 

DJ_Allatoona

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Feb 24, 2008
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186
You guys have helped me out a lot, Thanks. Fingers crossed this thing starts and runs for me.
 

shipoffools

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Jan 8, 2004
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IMAG0230.jpg
A little off topic but couldn't help notice the similarity in our rigs. Mine is a 76 18' SS with an 88 70hp Merc.

On topic, If you get the old motor running be prepared to replace fuel lines, fuel pump diaphragms and if your real ambitious rebuild carbs. Mine sat for a couple years before I fired it up and a lot of gaskets had dried out not to mention tons of gas varnish in everything.
 

DJ_Allatoona

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Feb 24, 2008
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Yeah, very similar! Trying to see where the extra two feet in length is between yours and my boat. Mine's 16ft. The bow looks the same. I even have the holes where that bow rail would go if someone before me hadn't removed it.

As for this motor, good call on the carbs. The carbs on my existing (seized) motor are in great shape (I know the gaskets/floats/needles), so I may just pop them in. The two motors are identical, so I have some cannibal parts for a little while, anyway.

Here's some pics of my Starcraft. Hopefully back up and running in a couple of days.
 

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DJ_Allatoona

Petty Officer 2nd Class
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Update: it started, but wasn't pretty. I'll spare the details, but the first attempt a few days ago showed me which fuel lines and gaskets had to be replaced, plus the tell-tale line was bad. Replaced all the things and returned to the lake today to try again. Victory.
 

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jimmbo

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Glad to hear you got it running. Nice little engine.
 
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