1975 Merc 115 inline 6, timing/fuel probs please help

Elpy54

Cadet
Joined
Jul 7, 2010
Messages
8
I have a 1975 mercury inline 6 115hp. I replaced the stator and rebuilt the fuel pump because the stator was bad and the engine was dying from what i though to be fuel issues(it would still idle). I took the flywheel off to replace the stator and got it out of time. I have ligned up the 3 dots on the flywheel with the distributor arrow, found tdc on cyl 1(this aligns timing arrow with tdc on flywheel) and measured .464 counterclockwise(which should be .464BTDC) but I cannot see a line on the flywheel for this. There is a really fine line on there so i used this but the label is nearly worn off. After all of this it would not start. Like an idiot I removed the distributor cap and have adjusted various screws around the distributor(throttle stop, spark advance, etc). Now the only way I can get the engine to fire is to spray gas in the cyls and then put the plugs in. Even by doing this it still will not start it just fires irradically(I think it should start for a few seconds). I also have fuel to the fuel pump, pumping out of the pump, and 2 the last carb so seems like it is getting fuel. Now can anyone please help me out? I would be more than willing to provide a cell number, answer pms, and emails(lpearman1@gmail.com)
 

jimdd810

Chief Petty Officer
Joined
Mar 18, 2006
Messages
532
Re: 1975 Merc 115 inline 6, timing/fuel probs please help

you need to order an oem factory manual for your engine and that will give you all the timing and adjustment specs. I would also look at rebuilding and cleaning the carbs. I wouldnt do that untill i got every thing adjusted to the right settings. Your never going to get it running right untill then
 

Elpy54

Cadet
Joined
Jul 7, 2010
Messages
8
Re: 1975 Merc 115 inline 6, timing/fuel probs please help

Ive used a seloc manual and it seems to be no help because I cant get it to idle to even consider setting the timing.
 

Elpy54

Cadet
Joined
Jul 7, 2010
Messages
8
Re: 1975 Merc 115 inline 6, timing/fuel probs please help

I understand but i hate to invest the 70 more bucks on something thats possibly junk.
 

usskydvr

Chief Petty Officer
Joined
May 27, 2009
Messages
494
Re: 1975 Merc 115 inline 6, timing/fuel probs please help

Take a look at the attached. Set your Max advance at 21 NOT 23 ( due to the difference in octane from years ago.
 

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CVX20SPRINT

Petty Officer 1st Class
Joined
Sep 9, 2009
Messages
213
Re: 1975 Merc 115 inline 6, timing/fuel probs please help

I've got a 73 150 l6 that a marina told me wouldn't run right because the reeds were done.I got a Merc manual and pretty much started from scratch.Motor runs good now after a bit of fiddling.You have to do the basic stuff...compression check,clean carbs,rebuild fuel pumps and most definitely a lync and sync.If the compression is good it is definitely worth fiddling with.They are great motors and newer replacements can get real expensive.
 

Elpy54

Cadet
Joined
Jul 7, 2010
Messages
8
Re: 1975 Merc 115 inline 6, timing/fuel probs please help

I have compression all cylinders 113-118 varies a little each time but thats the scoop.
 

Elpy54

Cadet
Joined
Jul 7, 2010
Messages
8
Re: 1975 Merc 115 inline 6, timing/fuel probs please help

New problem. I have a broken plastic linkage that goes from mid to bottom carb any idea where I can get one? Thanks for the help guys you are truely awesome.
 

usskydvr

Chief Petty Officer
Joined
May 27, 2009
Messages
494
Re: 1975 Merc 115 inline 6, timing/fuel probs please help

That part 12-53720A2 is NLA ,no longer available. You may be able to find one on Ebay or call around to any Mercury dealers to see if they have an old one laying around.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,930
Re: 1975 Merc 115 inline 6, timing/fuel probs please help

The new part # is 53720A2 and it shows NLA also.
 
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