Johnson J150VXSIG 2001 carb looper smoking badly, rough

[rothfm]

2nd post on my twin 150 motors. Had them long time always run well and I maintain them myself.

This spring, at initial start I thought all was well minus a bit of low idle (I know how to set lo idle on these).

But after more testing, it clearly isnt firing right. Smokes bad unlike its partner. Seems raw fuel is leaking down leg possibly from up top.

It starts up, goes into QuickStart till warm then drops rpm as it should. Just noticably rough and smokes alot

Spark is present on all 6, tried a new OIS I had handy-same. Im not messing with linkage as these always were in Sync and idled great.

Of Note...I did replace all 6 bowls as maintanance as some were warped. I keep a bolt in one home as each carb is removed to ensure throttle plate and rail stay tigh against block. Super careful. Nothing seems out of place, no timing or linkage was ever touched.

 

[fatlenny]

I assume you pulled carbs off the motor when replacing the bowls. All linkage is in place and not binding? can you view the bowls when running, are you seeing leaks around new bowls? Or fuel just spewing out of the carb throat? May have debris blocking the needle and seat from unhooking and reattaching the fuel lines (small piece of rubber hose common to find) causing a flooding issue and or float is binding for some reason, not reassembled correctly, or needle completely fell out of position and not properly set to the float. sounds to me like you may be pulling carbs back off.

 

[racerone]

What was done with high speed jets that were in the old bowls ?

 

[rothfm]

I assume you pulled carbs off the motor when replacing the bowls. All linkage is in place and not binding? can you view the bowls when running, are you seeing leaks around new bowls? Or fuel just spewing out of the carb throat? May have debris blocking the needle and seat from unhooking and reattaching the fuel lines (small piece of rubber hose common to find) causing a flooding issue and or float is binding for some reason, not reassembled correctly, or needle completely fell out of position and not properly set to the float. sounds to me like you may be pulling carbs back off.

Thanks..The 6 carbs are removed without removing fuel lines. The back throttle plate is what fuels them thru the mating surface. linkage is moving free. The throats seem much "drippier" that the other twin motor. I see the same fuel running down the leg.

 

[rothfm]

What was done with high speed jets that were in the old bowls ?

The same jets/orafice were moved to the new bowls after checking-This model has only 1 in the bowl. Plastic carb "bodys" come off with 4 bolts without removing anything else. I just replaced the warped bowls, moved over the 1 jet, and new bowl gasket.

 

[rothfm]

Guess I will remove all 6 again to investigate. I broke the top Encoder timing Disk, so one is ordered. I've had these 4 years now. Run great normally. I wonder if the prior owner had Mal-Adjusted the needle valves in each to over-compensate for the warped bowls that may have been leaking air? So now that I replaced the bowls, and its tighter- the ratio is off? Just a random thought. Unless its a coincidence, symptom was after I did the bowls. my luck anything is possible.

 

[racerone]

Yes , I know there is only 1 jet in each bowl.----Good luck with the investigation.

 

[rothfm]

Yes , I know there is only 1 jet in each bowl.----Good luck with the investigation.

Thanks Racer, Didnt realize that was you when I replied. The voice of authority on these. You've helped me alot in the past. Plan while waiting for new timing disk: Check those needle valve positions against the other motor. Pull 6 carbs and open again if needed. check any/all hoses seeams for leaks.

 

[rothfm]

Solved: 1 of the 12 carb body oring type gaskets that mate to the manifolold had a very slight "ding" in it. Was leaking fuel when pressurizing the bulb. Difficult to see as it was one of the lower ones. Had to take off all covers to view properly.