MacDaddy21
Petty Officer 1st Class
- Joined
- Feb 16, 2011
- Messages
- 280
I have been working on my 1979 402 for quite awhile now and have gotten into some tricky issues. Serial # is 5253808. What I have done this far:
1. Brand new CDI ignition module
2. Replace carburetor with newer cleaner carb
3. Wire in new ignition switch and replace 95% of all wiring
4. Replace fuel pump
5. Two new fuel filters
6. New fuel lines
7. New primer bulb and fuel hose with mercury fittings
8. Lower unit replaced with brand new impeller
9. New Rectifier
10. New starter motor
11. Replaced solenoid
12. Replaced coils and put new plugs in
*note - everything that was replaced came off my 1980 merc 402 parts motor, but all parts that were used had matching part numbers
So, after all that work was done, I got the motor to run, shift gears, and turn off multiple times without problem. However, I was having problems with the throttle control linkage getting stuck and the RPM's would stay high even though the motor was back in neutral. I pulled the linkage apart and lubed the return spring in the linkage. Today, I was running the motor but was having trouble with it dying on me due to what seemed like a lack of fuel. Also, the carb would flood and leak fuel when I primed the bulb. This seemed like a good excuse to clean the carb. So i pulled the carb and took the bowl apart, to find a large amount of gunk and build up in the bottom of the bowl. I cleaned the float and bowl thoroughly and then pulled the optimizer tube off (little piece of hose that runs from the bowl to the other side of the carb body). This is when it got weird. I pulled the hose off and tried to blow through it. No air would pass. So, I stuck a small screwdriver through the hose, and forced 2 copper coated BB's out of the hose. I called the Mercury dealer here and they said the hose should be empty, as it was supposed to regulate pressure between the bowl and the carb body. So I forced the BB's out and put the hose back on. I cleaned the rest of the carb body out and put it back on, and attached the fuel lines. Note, the carb did stop flooding and leaking fuel when I reattached it, UNLESS I primed the bulb too much. Then I put everything back together and tried to start the motor. It would start most of the time but was finicky with the choke and kept acting like it was starved for fuel. It would increase and decrease in idle RPM's, and had a mind of its own. I pulled the plugs to discover a thick black residue on them. I think this was due to the carb flooding and feeding too much fuel into the engine. So I cleaned the plugs and ran the motor a few more times and pulled the plugs after each run and they were clean with maybe a little fuel on them. My motor is still not running right and it is acting starved and running rough. I have not cleaned the jets yet but I don't want to if they don't need cleaning, and I am also nervous to remove them because I have never done so. The mixture screw on the carb is set at an approximate factory setting where you tighten the screw to a slightly snug seat and then back it off 1 1/4 turns, and I only did this because it is what I read on this site. I am not sure what exactly is wrong, but I think it must be carb related, and fuel related. I apologize for the long explanation, but I want the best possible response so I figured anyone helping should know the whole story. Any help is greatly appreciated. I will try to answer any questions to the best of my ability.
1. Brand new CDI ignition module
2. Replace carburetor with newer cleaner carb
3. Wire in new ignition switch and replace 95% of all wiring
4. Replace fuel pump
5. Two new fuel filters
6. New fuel lines
7. New primer bulb and fuel hose with mercury fittings
8. Lower unit replaced with brand new impeller
9. New Rectifier
10. New starter motor
11. Replaced solenoid
12. Replaced coils and put new plugs in
*note - everything that was replaced came off my 1980 merc 402 parts motor, but all parts that were used had matching part numbers
So, after all that work was done, I got the motor to run, shift gears, and turn off multiple times without problem. However, I was having problems with the throttle control linkage getting stuck and the RPM's would stay high even though the motor was back in neutral. I pulled the linkage apart and lubed the return spring in the linkage. Today, I was running the motor but was having trouble with it dying on me due to what seemed like a lack of fuel. Also, the carb would flood and leak fuel when I primed the bulb. This seemed like a good excuse to clean the carb. So i pulled the carb and took the bowl apart, to find a large amount of gunk and build up in the bottom of the bowl. I cleaned the float and bowl thoroughly and then pulled the optimizer tube off (little piece of hose that runs from the bowl to the other side of the carb body). This is when it got weird. I pulled the hose off and tried to blow through it. No air would pass. So, I stuck a small screwdriver through the hose, and forced 2 copper coated BB's out of the hose. I called the Mercury dealer here and they said the hose should be empty, as it was supposed to regulate pressure between the bowl and the carb body. So I forced the BB's out and put the hose back on. I cleaned the rest of the carb body out and put it back on, and attached the fuel lines. Note, the carb did stop flooding and leaking fuel when I reattached it, UNLESS I primed the bulb too much. Then I put everything back together and tried to start the motor. It would start most of the time but was finicky with the choke and kept acting like it was starved for fuel. It would increase and decrease in idle RPM's, and had a mind of its own. I pulled the plugs to discover a thick black residue on them. I think this was due to the carb flooding and feeding too much fuel into the engine. So I cleaned the plugs and ran the motor a few more times and pulled the plugs after each run and they were clean with maybe a little fuel on them. My motor is still not running right and it is acting starved and running rough. I have not cleaned the jets yet but I don't want to if they don't need cleaning, and I am also nervous to remove them because I have never done so. The mixture screw on the carb is set at an approximate factory setting where you tighten the screw to a slightly snug seat and then back it off 1 1/4 turns, and I only did this because it is what I read on this site. I am not sure what exactly is wrong, but I think it must be carb related, and fuel related. I apologize for the long explanation, but I want the best possible response so I figured anyone helping should know the whole story. Any help is greatly appreciated. I will try to answer any questions to the best of my ability.
