115 carb questions

[btroy]

I have a 1977 1150 Mercury,

This engine has never idled correctly and has alway given me issues. By that I mean hard to start, can not idle without the fuel enhancer up at least 3/4 the way. It must be up that far just to put it in gear without it dying.

Anyway, I attempted to readjust the carbs and I have to turn all 3 carbs out like 4 turns to get it to start. I have tried 1 1/2 to 4 turn and it will not start until I get about 4 turns out on each.

I took it to the boat mechanic and he said it was ok. Well I am not buying this. It should not be so hard to start and I would think it should idle without the enhancer up that far.

He also said it was in time, I would think if it were in time it would not take 5 minutes to start.

I am thinking it sounds like the carbs need rebuilt. What does it sound like to you?

I am thinking I might need to find a new mechanic.

 

[Bob_VT]

Re: 115 carb questions

Well the things I would do..... (have done and have the t-shirt)

When I had a 115 tower.....
Rebuilt the carbs...... tiny passages very clean (they are the idle circuits)
Rebuilt my fuel pump...... just for good measure.

and the MOST important item is the synchronization of the carbs and timing found here...... http://forums.iboats.com/showthread.php?t=168855

 

[Fuzzytbay]

Re: 115 carb questions

These motors are notorious for hard starting cold. You need to almost flood them to get them to run. Yes the fast idle lever must be up,ALL the way, and the choke must be used, and fuel bulb needs to be hard. Then they may need a quick choking while warming up, if they stumble. It may take 5 mins to get really warm, if the water/air/weather is cold.
Also they need pristine carbs, and yours don't sound like that. Also they need good fuel pumps, and no air leaks on the fuel system, ie Tank, bulb, bayonet fitting, and all fuel lines.
Do as Bob said, and all should be fine.

 

[Bob_VT]

Re: 115 carb questions

The other item about starting a "tower" is to make sure it is tilted ALL the way DOWN so the gas will flow into the motor. Look at the angle of the carbs and when the engine is tight against the transom so the gas will flow it helps.

 

[Chris1956]

Re: 115 carb questions

4 turns out on the idle mixture is unusual. It sounds like the carbs are not clean or the floats are not set properly. Nowmally we start the carbs at 1-1/2 turns out and need to add abour 1/2-3/4 turn to get them right. The motor should start easily at 1-1/2 turns out.

 

[Jeff_G]

Re: 115 carb questions

If the tech is under 45 don't let him work on the engine as he will have no experience. You need one of us old farts!!!

 

[btroy]

Re: 115 carb questions

thanks for all of your responces, that helps alot.

The guy I had working on it is an "old fart". I spoke to him and told him if they need rebuilt have at it. If not then take it to the lake and get it right.

He told me to bring it in next week and he will take care of it. So I will no more by the end of next week.

Thanks again for all of your help/input.

Safe boating!

Troy

 

[btroy]

Re: 115 carb questions

I added new fuel lines and it is now keeping the bulb hard. I still pump it a few times per weekend but I can live with that.

It is still hard to start, as in it takes along time. Even with good fuel I have to crank on it for at least 5-10 minutes to get it to fire off. This is only when it is a cold start.

Coil perhaps?

Where does the tach connect to.

On the back of the tach it has one wire going to the fuse box and the other wire goes into the engine housing but it is not connected.

 

[Chris1956]

Re: 115 carb questions

Those motors are hard to start when cold. You should follow the following: Cold start lefer all the way up, primer bulb pumped up firm. Now hold choke button down (should hear click as shutters close), and crank until it fires.

The tach needs connections to a source of +12VDC, ground and one of the yellow stator wires to provide the tach signal. The MerControl box usually has a three prong rubber connector designed especially for the tach. White is +12VDC, Black is ground, brown is tach signal.