imported_Jacko
Recruit
- Joined
- Sep 27, 2006
- Messages
- 4
BACKGROUND
2000 model carburated 150 Yamaha. 200-250 hours per year in mainly salt water. In 2001 a leak from water pressure gauge tubing soaked power head with salt water. Although the head was rinsed with fresh water and coated with light oil, corrosion initiated on the more corrosive components. Engine continually idled for many hours when fishing Boca Grande in 2003. After that, the engine never idled well. Burned out carbon once a year and changed spark plugs every other year. Also use Sea foam once per year. Always use Chevron, Shell, or Exxon in that order of preference.
After several years of poor performance from the low idle jets I finally had the carburetors rebuilt this spring. Since the motor died so often when idling the starter was worked way more than normal and eventually failed the starter relay.
MALFUNCTION AND TROUBLESHOOTING
A few weeks after the carb job, my son takes the boat out and does not get 5 miles before he looses power. I find the top left spark plug does not have continuity so replace it. No luck. Top end is normally 43 mph and it will only do 29mph. The boy had put Citgo gas in the tank. The water filter was full off water and old so I replaced it. Also drained the gas tank and back filled with good gas with no luck.
I take it to a mechanic whom checks fuel systems, spark, compression ect, and determines there is a bad coil since the new plug I had installed showed no signs of being fired. The new coil did not help.
I verify spark from all 6 coils and replace all 6 plugs. Also, since there was superficial corrosion on some connectors and ground points I take apart every connection related with the ignition system and clean them up. Some of the grounds were in poor shape. Also find that the carburetor job had resulted in no lock washers on the carbs and several gas lines with no hose clamps so I pull the carbs and assemble correctly ensuring there are no air leaks. Also find that the clip attaching the auto choke link is missing and replace.
After running with low power for several hours the top left spark plug still looks brand new, like no fire, but also notice that the other 2 plugs on that side show very little heat history. In fact, one of the other plugs not as clean, but looks nearly new. Suspect the CDI unit so I borrow the CDI of my brothers engine and find it does not help.
So what is common with the left side of the engine that is resulting in poor to no spark?
I pull the fuel pumps and find that the top one leaks from the mounting bolt holes when I pump the bulb. Even worse this fuel pump gasket is in terrible shape. It looks like it may be an air leak source. The fuel pump gaskets and diaphragms are replaced to no avail.
Next I pull the fly wheel and inspect the stator. It does not look good. 60% rust on the ends of the poles and on the ID of the stator. Also the mounting screws for a speed pick up are pretty corroded so the system is cleaned up and painted. Although the coils do not look bad I ohm all 6 circuits and the resistance meet specifications.
The engine will still not perform and Im running out of ideas. A mechanic told me that sometimes loosening the spark advance pick ups and resetting them a little closure to the stator will help? It seems like a spark advance (or carburetor) problem since when the throttle is slowly backed off from full there is a point when the engine will momentarily surge with power. Im guessing but is seems like this throttle positions is always at the point where the spark advance discontinues motion.
Ran the engine in the dark looking for sparks from bad wires in the ignition system, but did not find a problem
After a different CDI did not help and the stator circuits ohmed out OK I went back to checking the fuel system. Found what appeared to be a permanent kink in the fuel line, but removing it did not help.
The engine starts easily and idles smoothly, but has no power. Its not required to go to full throttle to note the engine is not performing. Even when quickly jumping from idle to one third throttle the lack of power is very noticeable.
Im back to wondering if the lack of spark is due to no fuel?
What should I do next?
2000 model carburated 150 Yamaha. 200-250 hours per year in mainly salt water. In 2001 a leak from water pressure gauge tubing soaked power head with salt water. Although the head was rinsed with fresh water and coated with light oil, corrosion initiated on the more corrosive components. Engine continually idled for many hours when fishing Boca Grande in 2003. After that, the engine never idled well. Burned out carbon once a year and changed spark plugs every other year. Also use Sea foam once per year. Always use Chevron, Shell, or Exxon in that order of preference.
After several years of poor performance from the low idle jets I finally had the carburetors rebuilt this spring. Since the motor died so often when idling the starter was worked way more than normal and eventually failed the starter relay.
MALFUNCTION AND TROUBLESHOOTING
A few weeks after the carb job, my son takes the boat out and does not get 5 miles before he looses power. I find the top left spark plug does not have continuity so replace it. No luck. Top end is normally 43 mph and it will only do 29mph. The boy had put Citgo gas in the tank. The water filter was full off water and old so I replaced it. Also drained the gas tank and back filled with good gas with no luck.
I take it to a mechanic whom checks fuel systems, spark, compression ect, and determines there is a bad coil since the new plug I had installed showed no signs of being fired. The new coil did not help.
I verify spark from all 6 coils and replace all 6 plugs. Also, since there was superficial corrosion on some connectors and ground points I take apart every connection related with the ignition system and clean them up. Some of the grounds were in poor shape. Also find that the carburetor job had resulted in no lock washers on the carbs and several gas lines with no hose clamps so I pull the carbs and assemble correctly ensuring there are no air leaks. Also find that the clip attaching the auto choke link is missing and replace.
After running with low power for several hours the top left spark plug still looks brand new, like no fire, but also notice that the other 2 plugs on that side show very little heat history. In fact, one of the other plugs not as clean, but looks nearly new. Suspect the CDI unit so I borrow the CDI of my brothers engine and find it does not help.
So what is common with the left side of the engine that is resulting in poor to no spark?
I pull the fuel pumps and find that the top one leaks from the mounting bolt holes when I pump the bulb. Even worse this fuel pump gasket is in terrible shape. It looks like it may be an air leak source. The fuel pump gaskets and diaphragms are replaced to no avail.
Next I pull the fly wheel and inspect the stator. It does not look good. 60% rust on the ends of the poles and on the ID of the stator. Also the mounting screws for a speed pick up are pretty corroded so the system is cleaned up and painted. Although the coils do not look bad I ohm all 6 circuits and the resistance meet specifications.
The engine will still not perform and Im running out of ideas. A mechanic told me that sometimes loosening the spark advance pick ups and resetting them a little closure to the stator will help? It seems like a spark advance (or carburetor) problem since when the throttle is slowly backed off from full there is a point when the engine will momentarily surge with power. Im guessing but is seems like this throttle positions is always at the point where the spark advance discontinues motion.
Ran the engine in the dark looking for sparks from bad wires in the ignition system, but did not find a problem
After a different CDI did not help and the stator circuits ohmed out OK I went back to checking the fuel system. Found what appeared to be a permanent kink in the fuel line, but removing it did not help.
The engine starts easily and idles smoothly, but has no power. Its not required to go to full throttle to note the engine is not performing. Even when quickly jumping from idle to one third throttle the lack of power is very noticeable.
Im back to wondering if the lack of spark is due to no fuel?
What should I do next?
.