1980 Mercury 115 won't start after sitting for 5 years.

tsimpson-az

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I bought a 1980 Merc 115 recently from a friend. The motor was working fine when last used but has sat in a garage for 4-5 years. I cannot get it to start. I put a new fuel line and bulb on it and when I pumped it I noticed the fuel pump was leaking. I rebuilt the pump with all new gaskets and it no longer leaks, however when trying to start the engine no fuel is coming out of the pump. Does it have to be running (higher RPM) before it starts pumping?
Also when I prime it I do see gas leaking out of the bottom of the three carbs so it is going through the pump to the carbs during prime, but it never acts like it even wants to TRY to start. I checked and I am getting spark. Could it be that the carbs need rebuilt too? I would think that it would at least try to run even if the carbs need work, especially since it ran fine the last time it was on the water. Thanks for any advice!
 

1fishbone

Chief Petty Officer
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Re: 1980 Mercury 115 won't start after sitting for 5 years.

"Could it be that the carbs need rebuilt too?"
ABSOLUTELY!!
4 or 5 years years without running a LONG TIME!

Stop wasting your time and the possibility of burning out your starter!
Check the compression and move on to re-building the carbs.
Then replace the water pump and lube the lower unit

Read this:
http://forums.iboats.com/showthread.php?t=158086
And this:
http://forums.iboats.com/showthread.php?t=244013

FYI the choke is in the key, push the key in and turn to start...holding the key in.
 

arsenalpsu

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Re: 1980 Mercury 115 won't start after sitting for 5 years.

Unless the carbs are 100% plugged she should at least start up. If they're dirty it would run lean and cause you other issues but I would say it should start. I would clean the carbs, but I think too many people blame dirty carbs for just about everything. More likely they need to be adjusted or your timing is off. Make sure you have spark ON ALL 6, did you check that? Do a link and sync. And it is normal for fuel to leak out of the carbs when starting these old girls. Did you incrase your idle lever (or advance throttle in N if newer controles) and use the choke?
 

tsimpson-az

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Re: 1980 Mercury 115 won't start after sitting for 5 years.

Thanks for the feedback!
To answer some questions, I replaced the water pump and I ran a compression test on all 6 before starting it and they are all 135-140. I only checked spark on 1 but I will check all 6.

The electric choke is working and I am using it while trying to start it.

It wouldn't surprise me at all that the carbs would need rebuilt, I just thought it was odd that I was getting no effort to start. I didn't try changing timing yet; wouldn't know how to.
 

1fishbone

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Re: 1980 Mercury 115 won't start after sitting for 5 years.

Unless the carbs are 100% plugged she should at least start up. If they're dirty it would run lean and cause you other issues but I would say it should start. I would clean the carbs, but I think too many people blame dirty carbs for just about everything. More likely they need to be adjusted or your timing is off. Make sure you have spark ON ALL 6, did you check that? Do a link and sync. And it is normal for fuel to leak out of the carbs when starting these old girls. Did you incrase your idle lever (or advance throttle in N if newer controles) and use the choke?

All it takes is a speck to lodge in the small jet opening and it's 100% clogged:)

Spark is also necessary...assuming he already checked all cylinders was my error!
 

arsenalpsu

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Re: 1980 Mercury 115 won't start after sitting for 5 years.

No errors friend, we're all here giving our opinions. I wasn't refering to your recomendations as incorrect, i just think that too many things are blaimed on the carbs being dirty, but his sure could be. That being said I've started an inline with 3 dirty carbs and spark in 3 cylinders. Anyway, compression looks great, make sure you increase the throttle or idle lever when trying to start. Let us know how it goes. OH- and to your question about the fuel pump, you said it's not pumping, how do you know that? There will be no indication it's pumping when you're just trying to start her. All the fuel for starting come from the primer filling the carbs.
 

joed

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1,132
Re: 1980 Mercury 115 won't start after sitting for 5 years.

Take some of the fuel and squirt some directly into each carb or even into each cylinder through the sprk plug hole. Try cranking it and see if she fires. If it does then look for carb issues.
 

tsimpson-az

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Re: 1980 Mercury 115 won't start after sitting for 5 years.

No errors friend, we're all here giving our opinions. I wasn't refering to your recomendations as incorrect, i just think that too many things are blaimed on the carbs being dirty, but his sure could be. That being said I've started an inline with 3 dirty carbs and spark in 3 cylinders. Anyway, compression looks great, make sure you increase the throttle or idle lever when trying to start. Let us know how it goes. OH- and to your question about the fuel pump, you said it's not pumping, how do you know that? There will be no indication it's pumping when you're just trying to start her. All the fuel for starting come from the primer filling the carbs.

As to the question of how I tested it. I left the inlet hose from the tank hooked up to the pump but disconnect the outlet hose that goes to the carbs and put the end of that in a bottle then turned the motor over several times. I expected to see some fuel pump out like it used to on the old V8s (cars) with mechanical pumps. Is this not a valid test procedure? Thanks!
 

arsenalpsu

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Re: 1980 Mercury 115 won't start after sitting for 5 years.

I'd say no, not a good test- you have such a low RPM that way you won't have proper pressure for the pump to work. This would be a none issue when starting anyway b/c you fill the carb bowls with the in-line primer bulb. Once she fires off it would run until you empty the carbs. You need 3 things for her to fire off, fuel, compression, and spark, and all much be timed correctly. Do a link and sync, check to make sure all carbs are opening/closing together. If she has spark in all 6 and you've verified the timing is set correctly and she still won't start, buy some 2 cycle starting fluid and spray it into each carb- then try and start. Once she gets going everything will lubricate and get nice and warm and it may clear its self out, but i would still clean the carbs.

At this point if you don't have one already go buy a Mercury OEM manual- search ebay. If you plan to do all your own work on the old girl this will save a lot of time and frustration
 

tsimpson-az

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Re: 1980 Mercury 115 won't start after sitting for 5 years.

Finally got it running! I tested for spark on all plugs and 2 of the 6 were not getting spark. After exhaustive testing I found out the switch box for the upper three cylinders was bad and so I replaced that with used one I happend to have. The other was just a bad connection. Once I got them all sparking, it fired up and ran. I appreciate everyone's help here!
 

arsenalpsu

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Re: 1980 Mercury 115 won't start after sitting for 5 years.

Congrats, what a great feeling isn't it!
 
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