1976 mercury 1150 115hp runs on muffs but not in lake

[1976mercury115]

My 1976 mercury 115 runs great and revs fully with muffs but as soon as i put it in the water it will start and idle but likes to stall going into gear. When i do get it in gear it will slowly speed up but only get half throttle and wont go over 20 mph. It also doesnt like to start after the motor gets to operating temp if i get it to go and drive it for a bit it wont start back after i turn it off. I bought this boat in june non running and ive fixed it up so far ive cleaned the carbs and i had to take the distributor out and fix the power wire when putting it back in im pretty sure i got all of the spark plug wires in the same spot but not 100%. Im also pretty sure i got the timing correct i couldnt find directions on setting the timing but i found a youtube video and went off that. So idk if i didnt put the distributor back in time correctly or if its somthing different alltogether. I also checked the compression on all the cylinders they were all a healthy 120 psi i also checked spark on all cylinders and they all get really good spark. this is my first 2 stroke motor ive ever worked on so im lost on what could be causeing my problems.

 

[racerone]

Open low speed fuel mixture screws 1/8th turn at a time and test run.

 

[1976mercury115]

Open low speed fuel mixture screws 1/8th turn at a time and test run.

I tried that the other day and i got them set to where i think was the best and it made it a little better but it still wouldnt accelerate or go into gear without almost stalling or stalling.

 

[Chris1956]

The distributor cap usually has cylinder numbers molded into it, so you can put the spark plug wires on correctly. The distributor cap has to fit on a raised area of the distributor body, so it is on correctly. You can put it on wrong, but it won't completely mate to the metal distributor body. Obviously you need to make sure the cap is on the distributor properly. Remove the locking ring and turn the cap until you feel it mate with the raised notch. When she is running on the flusher, watch/listen for sparks from the spark plug wires to ground. If you hear/see it, replace the wires.

To time the distributor, remove the distributor pully cover. Set the motor to top dead center. Now make sure the cast arrow on the dist. pully points to the one or three dots on the flywheel timing label. Remember the timing pointer on your motor is adjustable, so check to make sure when the #1 cylinder is at TDC, the timing label TDC mark is pointed to by the timing pointer.

Have you check the compression on your motor? They sound real good on a flusher, but make no power if one or more of the cylinders is bad. Number 1 and 3 usually fail first. Make sure to run fresh 50::1 fuel mix so the carbs are set properly.

 

[1976mercury115]

The distributor cap usually has cylinder numbers molded into it, so you can put the spark plug wires on correctly. The distributor cap has to fit on a raised area of the distributor body, so it is on correctly. You can put it on wrong, but it won't completely mate to the metal distributor body. Obviously you need to make sure the cap is on the distributor properly. Remove the locking ring and turn the cap until you feel it mate with the raised notch. When she is running on the flusher, watch/listen for sparks from the spark plug wires to ground. If you hear/see it, replace the wires.

To time the distributor, remove the distributor pully cover. Set the motor to top dead center. Now make sure the cast arrow on the dist. pully points to the one or three dots on the flywheel timing label. Remember the timing pointer on your motor is adjustable, so check to make sure when the #1 cylinder is at TDC, the timing label TDC mark is pointed to by the timing pointer.

Have you check the compression on your motor? They sound real good on a flusher, but make no power if one or more of the cylinders is bad. Number 1 and 3 usually fail first. Make sure to run fresh 50::1 fuel mix so the carbs are set properly.

All of my cylinders have 120 psi, i have put in fresh gas the other day. I also replaced all plug wires i do know its seated correctly but ill have to check to see if i see any numbers on the cap and check i have them all connected correctly if that checks out ill recheck the timing thanks for your help.

 

[Chris1956]

After you get the distributor timed, check the timing pointer for accuracy. After that is done, check/set the idle pickup and max spark advance timing events.

The idle pickup timing on those distributor models is set by rotating the brass-colored collar on the distributor, to open the carbs, when the timing is 4-6* BTDC. So you set the timing to 4-6*BTDC, and then rotate the collar to touch the top carb lever, and lock the collar. Two bolts that need a 5/16" wrench lock the collar.

Max spark advance is 21*BTDC, and set using the max spark advance set screw on top of the distributor.

The other set screws are for idle stop (idle speed), and throttle stop. Often the throttle cable needs to be adjusted to push the throttle closed to achieve proper idle RPM.

You want idle RPM to be 800-900, if you can. 1200 RPM is too high and the gears will suffer.

 

[racerone]

Have you put a new water pump impeller in every 4 / 5 years or so.

 

[jimmbo]

Idle Rpm is specified 600-650, in gear

 

[Chris1956]

Sure, Idle RPM should be 600-650 in gear, and 800-900 in neutral.

Those motors sacrifice idle quality for quick smooth acceleration, so find an idle RPM you can live with as long as she accelerates smooth. You cannot have both, due to the design of the carbs.

Fresh 50::1 fuel helps idle quality a lot.

 

[1976mercury115]

Im gonna try and check the firing order and timing tonight and ill let you guys know what happens with it.

 

[1976mercury115]

I checked the plug wires and two of the wires were on wrong so i changed them and it wouldnt start anymore after that. So i took number one spark plug out and used a dial indicator to find exact tdc and my pointer was a little off. I also had the timing off so i fixed the pointer and changed the gear so that when at tdc it pointed to the dot on the flywheel. After i did all that i tried to start the motor and got it to almost start but my starter ended up finally quitting. Its been on its last leg for a while so im gonna either get it rebuilt or buy a new one and hopefully i can get the motor to start after that.

 

[Chris1956]

Carbs should be set to 1-1/2 turn open, and adjusted in the water, from there. Do not exceed the max spark advance of 21*BTDC.

After you get her to run, if she still doesn't run well, check the spark plugs for their color. Brown/black are good, but clean is not good. A clean spark plug implies water ingestion.

 

[1976mercury115]

I got the starter working while im waiting for my new one and the motor will pop off and almost start if i use some starting fluid so i think i have some kind of fuel issue now. It will also almost start if I squeeze the primer bulb really hard. How should i test if the fuel pump is working well?

 

[Chris1956]

No, as long the the primer bulb is hard, the carbs have fuel. Choke the crap out of her. Cold start lever high, hold choke button while cranking, until she fires. Hold choke for a bit and then feather it out, until she is warmed up.

Make sure the voltage on the switchbox red and adjacent white wire is +12VDC.

 

[1976mercury115]

Ill check the voltage but ive been trying to start it with coldstart lever all the way up and squeezing the primer before cranking aswell as choke and all it will do is almost fire.

 

[Chris1956]

Make sure your starter is spinning at 300RPM or so, to help it choke up.

 

[1976mercury115]

I got my new brushes for my starter today and now the starter is spinning the motor way faster but its still not starting i sprayed some seafoam spray in the the carbs but it didnt help any it just backfires. So is my timing still off or could it be that i need to do a link and sync to set my initial spark?

 

[racerone]

Check belt timing.====Check plug wires are going to correct cylinders.

 

[Chris1956]

Clearly it is time to check the timing. Remove the spark plugs and prop. Set the throttle to a position where the carbs are closed but ready to open. Crank motor with timing light on #1 cylinder. Timing s/b 4-6* BTDC. Carbs s/b open 1-1/2 turns.

 

[1976mercury115]

Now i have a new problem my power wire going to the distributor broke off inside the distributor could i take the distributor apart and soder a new wire in? I already looked to just buy a new one but i cant find any. I looked at it a little bit and it looks like the wire is sealed in rubber inside the distributor. Should i just try and find a used one or whats the best option here.