1977 Mercury 150 Inline 6 fuel problem

[Bke12345]

Ok all. I have a 1977 Mercury 150 inline 6. So Iv posted a couple post on problems that Iv fixed thanks to all that helped. None I’m stuck. So 2 weeks ago I was able to start the engine up everyday for a week. The weekend came and I took the boat out on the water. I put it in gear and it stalled out every time when put in load, so I adjusted the needles with the springs on the carbs as told, to where it stumbles and then back out 1 full turn. It worked alittle but not fully well. I took it home and didn’t work on the boat for 2 days. Then the boat wouldn’t start with fuel. I sprayed starter fuel in the 3 carbs cause I didn’t have any gas to spray. 3rd carb nothing 2nd carb nothing 1st carb it fired and ran for awhile and would start back on over and over. When adjusting the carburetors with the needle with the spring on it the second carburetor was the only one that would not Stall the motor out if I turn the needle all the way into close. Now taking mine I replace all fuel lines rebuilt the fueNow taking mine I replace all fuel lines rebuilt the fuel pump and rebuilt all three carburetors with floats and needles. Could it be possible that the car riders are getting clogged up again due to the fact that this motor has not been ran in several years and also could it be a compression problem even though the compression test ran between 118 and 120

 

[racerone]

Other than jumping all over the carburetors what other trouble shooting was done ?-----Does spark jump a gap of 3/8" or more on all leads ?----If there is no response when adjusting low speed mixture on the middle carburetor there may be a crankcase compression issue.------Reed valves or labarynth seal.

 

[Bke12345]

Well I did found out that the 3rd spark plug Spark was jumping around the spark plug test compare to the others. I also noticed that if the motor had running I tired to remove 1 spark plug at a time to see if the rpm or if the engine would struggle to stay running and I found that #3 spark plug when removed did not effect anything but did shock me though but none of the others wouldn’t

 

[Bke12345]

I do have the BUHW NKG spark plugs

 

[Bke12345]

Primer bulb has been replaced and operating correctly. I did mess with the spark advance( Adjusting that because it was idling too high off the distributor cap

 

[racerone]

You have to investigate / look for issues with # 3 cylinder

 

[Bke12345]

Ok. I’ll run another compression test tomorrow because it’s been a few months and I can take of the side of the exhaust plate to look at the pistons to see what the conditions are

 

[Bke12345]

Ok so I did a compression test and all 6 cylinders read between 130- 145 so compression tested good. Is it possible That I have the timing wrong on It or maybe because I need to Link sync The carbs a certain way.

 

[Bke12345]

 

[Bke12345]

 

[Chris1956]

You will want to make sure the link and synch are done properly, or you could damage your motor. Do you have a service manual? If not you might get one. A OEM service manual is vastly superior to an aftermarket one.

Remember, the idle pickup timing is adjusted using the brass collar which is about 1/2 way up the distributor body. Max spark advance, idle stop and throttle stop are adjusted using the set screws above the distributor.

The timing pointer should be set to make sure it is accurate, using a dial gauge or at least a caliper.

 

[racerone]

Perhaps an issue with a reed valve for # 3 cylinder.

 

[Bke12345]

Well I did check the reeds with a strategy I seen on YouTube where someone places a piece of paper over the carburetor and if trying to start it the paper would try to suck in and the reed valves are good, which I did the paper test and they all seem to do that.

 

[Bke12345]

Chris1957, I’ll look into that. Thanks