Carb leak and dripping, and the motor can not idle.

tavacska

Petty Officer 1st Class
Joined
Jan 21, 2017
Messages
247
I tried to start the 77 mercury 1150 after replacing the distributor trigger, cleaning the carb and rewiring.

It is very hard to start unless I rotate the distributor half way between the idle and second pick up.
I noticed there is gas leaking from 1-3 carbs and the dripping pan is almost full of gas.
Here below is some check I did to identify the issue.

1. Float and needle and seat. I opened the float bowl twice and cleaned it well. The floats are not leaking, the springs are 3/32 inch. The gaps between arms are all good. The needle, seat and gasket are cleaned and air sprayed as well. And I tried to mouth blow the inlet with hand blocking the needle, the mechanic is good.
After assembling, I tried very hard to squeeze the bulb, and found only one or two dripping from carbs.

2. The rectifier is good. It's a new sierra replacement and test good.

3. The stator, I dont know. I use multi-meter to check the Hz between the yellow lines, it reads 1.0 k hz. The volt before start is 12.4 volt, the volt when the motor is running is 12.8 volt. When the motor is running, I pull the engine "+" lead from the battery, the motor stop immediately. It can not run without a battery.

4. The timing, I think is good. When doing battery cranking, the first pick up is 5 BTDC, the max advance and second pick up is 20 BTDC. I set the idle stop at 0 BTDC, but never worked in that position.

5. The compress pressure is 120 psi tested for all cylinders before I put the lower unit on and running the whole process with gas.

6. The idle mix screw is set 1 1/2 from lightly seat position.

7. When I clean the carb, several screw is not able to get off. I leave it on and put all in the carb can for 48 hours. And cleaned all the passages with compressed air.

8. The spark cable dose have some problem. But I checked and repaired them all. I used in line spark test and timing light to have it tested. The spark test kit and timing light are lighting for all the cylinders.

The above is all what I did. The following is what is happening now.
1. When I set the distributor at idle position, the motor can not start. I see a lot gas leaking from the open mouth of carb, 1, 2, and 3. The dripping pan is almost full.

2. When I set the distributor at between idle and second pick, it starts up and can run for a long time. But the rpm is high.

3. My original tachometer is not working. I don't know if it is damaged or the startor-rectifier system is bad.

4. I used multimeter to test the Hz between the yellow lines from stator, it reads 1.0 k Hz.

5. I used KEDSUM hour meter Tachom, which is a black box with simple digits reading on it. The battery of the box can not be changed. It reads 4000-10000. The wiring is set up on the spark cable of the first cylinder.

6. When the motor starts, I think at a pretty high rpm before throttle is opened, I set the mixer screw following the manual. Turning it clockwise until unstable and turning counter clockwise 1/4-1/2 turn. I set the screws for all the three carbs.

7.When it is running, it looks like the dripping does not happen.

8. When I try to turn the distributor to idle position which is 0 BTDC, it stops very easily.



Please help with the above information. It drives me crazy for weeks.

Thanks.
 

merc850

Commander
Joined
Jul 7, 2010
Messages
2,055
Disconnecting the battery cable probably destroyed the rectifier if the tach is an alternator one it won't work now. The idle stop should make the motor idle at 600rpm - turn it in until the motor reaches that speed in gear in water. You must set the low speed needles in gear too. Are you following the starting instructions? http://forums.iboats.com/forum/engin...a-2-cycle-merc - post some pictures of the tach and motor. Idle setting can't be 0* it must be before TDC (at least 4-6*) check your manual again.
 

tavacska

Petty Officer 1st Class
Joined
Jan 21, 2017
Messages
247
Thanks, merc850, Picture 1.jpg

It seems I got a lot wrong information from surfing the web.
One guy says to test if the charging system work, you can disconnect the battery while running. It keeps on running, the charging system works.
The manual doesn't mention the idle ignition degree. It only mentions the primary pickup as 4-6 BTDC and Max Timing as 21 BTDC. My setup is 5 BTDC and 20 BTDC. But one guy from youtube says the idle will be around 0 BTDC.

As for the starting instructions, my remote control does not have a warmup lever. it has only a button which will not engage gear change while changing throttle.
My boat has the mercury desk top gear control. The ignition key and choke button is on the dashboard.

The rectifier I check again on bench. Looks like it is not damage by my experiment.

I am trying to set RPM to 800 in neutural and 600 in forward in water.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,545
The internet has it's share of bad info. You have found some.

A 1977 Merc inline six will have a battery powered ignition system, with a distributor. The charging system is totally separate from the ign system. If you disconnect the battery cables, the motor will stop, and likely ruin the rectifier. Since the rectifier charges the battery, after it breaks, you will not recharge the battery.

Idle pickup timing is 4-6* BTDC. Remove spark plugs 2-6 and the prop. Loosen the two bolts (5/16" wrench) that hold the brass collar that opens the carbs to adjust idle pickup timing. Jumper the starter solenoid (ign on) and set the idle timing (throttle only setting) to 4-6*BTDC and then adjust the collar to start to open the carbs. Tighten the bolts. Now set the motor to WOT and crank her and set the max spark advance set screw to 21* BTDC.

Install spark plugs, attach flusher and start motor. Set idle screw to allow the motor to run at 1100 RPM. You may need to adjust the throttle cable to pull the throttle closed.

Launch the boat and set the idle mixture screws to fastest, smoothest idle, in gear with the motor warm and fresh fuel. Now try to accelerate the boat. She will likely stumble and may stall. Open the top carb mixture screw 1/8 turn and retest acceleration. Repeat with mid carb and bottom carb, in that order, until you get decent idle and smooth acceleration. You are looking for as rich a mixture as possible to allow acceleration, yet still allow a reasonable idle.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,936
When the motor is running, I pull the engine "+" lead from the battery, the motor stop immediately. It can not run without a battery.
DO NOT DO THIS !!!! It will kill the trigger!!!!
 
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