1981 Mercury 115 inline

[skhourey]

rebuild carbs,new stator,reset everything by sight and ear thanks to all of your info.Boat has never ran better except if i slowing build up speed it will go about 5500 rpm,but if I gun it on take off it goes up to about5000 rpm and bogs down till I start over slower.Do you think idle mixture screws should be turned in a little.Thank You, Mudcarp

 

[Bob_VT]

Re: 1981 Mercury 115 inline

Recheck your link and sinc. Your timing may be off a bit and then re-adjust the carbs. The Linc & Sinc procedure is listed in the FAQ. You might be dumping too much gas for the timing and the engine has to catch up. That would be the first thing to check.

 

[Chris1956]

Re: 1981 Mercury 115 inline

Mudcarp, It is not advisable ot set timing by ear, due to inaccuracy. I recommend using a timing light.

As for your problem, it is a stumper. Perhaps your fuel pump cannot keep up, when you gun it. Will it continue to run at 5500RPM, if you slowly build speed?

 

[Texasmark]

Re: 1981 Mercury 115 inline

Hey guys,

Read several times on here that if you load up a tower it won't punch out. Heard that loading up is primarily caused by too high a pitched prop.

I guess if he can nurse it to 5500 he isn't running too high a pitch, but my '89 115 tower ran 6 grand without blinking and I never had any kind of load up problem.

So is there something to loading up? Like do the plugs foul out with too much fuel like you are talking about here when you hammer down on it?

Mark

 

[Chris1956]

Re: 1981 Mercury 115 inline

Mark, Installing a prop with two inches of pitch more can change an inline from popping skiiers out of the water, to not achieving anything more thn fast idle.

ie, I could pull two skiiers on my 1500 with a 21" pitch prop, but could not get more that 2000 RPM trying to ski one person using a brand-new 23" pitch prop.

 

[Texasmark]

Re: 1981 Mercury 115 inline

Well, is there something here that we are missing; like maybe he is running too much prop. .)

Mark

 

[realfastbug]

Re: 1981 Mercury 115 inline

I have a very similar problem but mostly only if I idle for too long like while a skier is getting ready for too long. If we are cruising around from 20 -40 mph then stop and idle for a second then hammer it then it seems ok with a slight hesitation. However if we hammer it after idling for too long it will kill the motor if you hammer it to pull a skier up.
Some background, I am pretty new to boats but handy in the way of cars. I just got this boat and the guy said he rebuilt the carbs. I found the timing to be way out of adjustment so I set that up the other day and have the carbs adjusted at 1 or 1.5 turns out. I also noticed the priming bulb has a pinhole on the engine side of it (I bought a new one but haven't installed yet). I also checked the compression and they are all between 105 and 110. My first plan to try adjusting the idle screws at the lake next time we are out. Any other suggestions? do you think this is a loading up of fuel issue too?
Thanks

 

[realfastbug]

Re: 1981 Mercury 115 inline

I just read through the FAQ again and one question came up, when setting the timing with the throttle in the idle position are you setting it to 4-6 deg BTDC or ATDC? I used the clumer manual and it said to set it to table 12 primary something or other and that line said BTDC but I did see another setting mentioned at ATDC(retarded more) if this is the case it looks like my timing will need more attention, no problem I guess I have to take the boat out again

 

[Scaaty]

Re: 1981 Mercury 115 inline

I have a very similar problem

Don't hijack another persons thread,,start you own..

 

[realfastbug]

Re: 1981 Mercury 115 inline

Are you serious? this thread is like a year old and addresses the same problem and continuing it in the same place would be much more valuable to people doing searches for help. But if thats the "policy" here I'll repost it. At least you were polite about it....oh wait...

 

[Tadd_P]

Re: 1981 Mercury 115 inline

I have a very similar problem but mostly only if I idle for too long like while a skier is getting ready for too long. If we are cruising around from 20 -40 mph then stop and idle for a second then hammer it then it seems ok with a slight hesitation. However if we hammer it after idling for too long it will kill the motor if you hammer it to pull a skier up.
Some background, I am pretty new to boats but handy in the way of cars. I just got this boat and the guy said he rebuilt the carbs. I found the timing to be way out of adjustment so I set that up the other day and have the carbs adjusted at 1 or 1.5 turns out. I also noticed the priming bulb has a pinhole on the engine side of it (I bought a new one but haven't installed yet). I also checked the compression and they are all between 105 and 110. My first plan to try adjusting the idle screws at the lake next time we are out. Any other suggestions? do you think this is a loading up of fuel issue too?
Thanks

change that primer bulb that has a lot if not all to do with it man

 

[realfastbug]

Re: 1981 Mercury 115 inline

thanks, I was wondering about that, seems so small a thing, but I did get one and will put it in before i go out again.

 

[Scaaty]

Re: 1981 Mercury 115 inline

Are you serious? this thread is like a year old and addresses the same problem and continuing it in the same place would be much more valuable to people doing searches for help. But if thats the "policy" here I'll repost it. At least you were polite about it....oh wait...

Actually the policy is to not pose a question/problem of your own on top of another's. Now a SOLUTION, even a guess is fine, but you added your comp ratios, your primer bulb, your background...
NOW, thing is...

This post was done and ended almost a year ago. Seems you searched, and replied to it....not the way its done. Search is for Reference, not replying and bring up a year old post. And I was polite..ya should see me when on a roll..