I got a couple of questions for Merc 115 Owners!

[wilson750]

I have a 87 Merc 115 inline 6, I took it out for the first time sat...Its a real pain to start..I did a search and see that all of them are!! I wanted to know how big of a batt would you suggest? Also It will not idle!! Do you think i should adjust the cable on the side of the motor? Or do some sort adjustment to the carbs? I have a manual on the way!!

Thanks

 

[nativetexantim73]

Re: I got a couple of questions for Merc 115 Owners!

Use at least a 775 CCA cranking battery.

 

[wilson750]

Re: I got a couple of questions for Merc 115 Owners!

Ok so just get a cranking batt for these towers of power? Thanks

 

[bullbat]

Re: I got a couple of questions for Merc 115 Owners!

i use an 850 cca batt

 

[wilson750]

Re: I got a couple of questions for Merc 115 Owners!

Thanks Bull!! I started the motor up again to see if i can see whats going on with the idle, I seems to be missing now, and that is whats making it stall!! The thing is it was running perfect a week before!! It was idleing perfect,but now it seems to be stalling when its low RPM.. Would a bad fuel filter do this? When i had it on the river it would not idle. But it would do 34MPH!! Would it run like that if it was only running on 5?

 

[OldMercsRule]

Re: I got a couple of questions for Merc 115 Owners!

Bad fuel will cause you all sorts of troubles so only use questionable fuel if ya really REALLY want to werk on yer engine and have a lot of extra money n' time ya wanna donate to yer boating cause.

I only have one ADI inline6 , (which my son blew up), so I would not be much help to you gettin' that beast to run right.

A few pointers: #1 Verify HOT spark on each plug wire, #2 check cornpression are the basics to start with. If yer missin' a spark or two follow the trouble shoot proceedure, to find out why.

If ya ran some junk fuel in the old girl, after cornpression n' spark are verified: take the fuel pump apart and rebuild it, and hope the screen caught all the junk ya fed yer carbs. If not totally rebuild the carbs, n' linc n' sync (AFTER ya verify spark and even cornpression as I said earlier).

I prefer the older distributor/battery fired ones, (not that they are any better), they are just simpler fer a simple feller like me ta werk on n' run.

Good luck with yer engine. Sounds like ya need some. JR

 

[wilson750]

Re: I got a couple of questions for Merc 115 Owners!

Thanks Oldmercs, Im going to check the compression this week!! When i had it on the river sat it would stand right up on plane!! Its on a 19' CC If its only running on 5 it must fly on 6!!! I was doing 30-35MPH.. It just wouldnt idle well!! Would it run that good with one not fireing?

 

[wilson750]

Re: I got a couple of questions for Merc 115 Owners!

Its all new fuel!! I drained all the old fuel out of the tank!! Put fresh low Oct in!! 50:1 mix

 

[OldMercsRule]

Re: I got a couple of questions for Merc 115 Owners!

Its all new fuel!! I drained all the old fuel out of the tank!! Put fresh low Oct in!! 50:1 mix

USE MID GRADE, (89 octane). If ya filled 'er with regular, fill an equal amount of premium n' premix.

TRY ta stear clear of alcohol if ya can!!!!

She is likely runnin' on all 6 if she was draggin' one you would likely know it, (IMHO).

Those old inlines were very good engines, (in fresh water).

Ya may also want ta run Seafoam ta remove carbon n' clean the junk outa the fuel system. JR

 

[wilson750]

Re: I got a couple of questions for Merc 115 Owners!

YEah she wasnt draging!! When i was on plane it go WOT and it would pull strong!! Ill do a comp test and throw some seafoam in there also!!

 

[wilson750]

Re: I got a couple of questions for Merc 115 Owners!

Ok i went out the the motor todat an pull the plugs to see how they looked after runnning her!! They all had alittle oil on them!! It just came right off with a rag and they went back in looking brand new!! Should they be that clean? It was just alittle oil, like a couple speck on all of them!! Never seen plugs soo clean after running!!

 

[Plainsman]

Re: I got a couple of questions for Merc 115 Owners!

The oil on the plug is ok. Remember that you are burning it with the fuel. Follow OMR's advice and rebuild the fuel pump and soak the carbs and rebuild them also.

 

[Starcraftguy1]

Re: I got a couple of questions for Merc 115 Owners!

Carbs and fuel pump,a must.Especially if it is new to you.You never know what the other guy did or did not dnce you do that,the rebuilding of course,and take care of it the way that you are supposed to.You will never have that problem again.Good luck.

 

[wilson750]

Re: I got a couple of questions for Merc 115 Owners!

Thanks for the help!! I think first im going to run a comp test!! Then do the others!!Thanks

 

[OldMercsRule]

Re: I got a couple of questions for Merc 115 Owners!

I dunno if I agree on the carb rebuild jus' yet, as I try NOT ta fix unbroken things, if at all possible.

Ya said the engine ran out well trough the power range, it jus' had a bit of an idle issue which could be some very minor, (or possibly some major) things.

If yer carbs are or were that bad methinks the problems would be much greater then you are now experiencin'.

Since ya ran some fuel of unknown quality and the fuel pump is soooooo darn easy ta get at I would fix that (unbroken or not) after the cornpression check.

Then I would run some Seafoam with yer fresh fuel and try ta richen up the carbs a wee bit ta see if the idle issue improves.

If all else fails (and yer reeds appear ta be in good shape, [the major thing I was referrin' to above ^^^^]), I would then R & R the carbs and linc n' sync.

Me over priced $.02. Hope it helps ya. JR

 

[wilson750]

Re: I got a couple of questions for Merc 115 Owners!

Thanks JR, I didnt run any old gas!! I put fresh 87 in it!! im going to do the compression test, then im going to do the sea foam,unless the comp test is really bad!! But i doubt that is the problem since it would scream up the river!!!

 

[OldMercsRule]

Re: I got a couple of questions for Merc 115 Owners!

Thanks JR, I didnt run any old gas!!

OH, I guess I miss read yer post, sorry.


I put fresh 87 in it!!

That is too low of octain, but if ya wanna put some holes in yer pistons, that is fine by me as they are yer pistons, not mine.

Mid grade, (89), is what the big guns have recommended here in past posts, (I used to waste me money on 92 before I learned that). I guess I have warned ya twice now so yer on yer own.


im going to do the compression test, then im going to do the sea foam,unless the comp test is really bad!! But i doubt that is the problem since it would scream up the river!!!

Sounds like a plan to me. JR