Popping and revving?

[Mystic Mariner]

I just put a new head gasket on my Johnson 45 HP commercial, pressures are 145 upper, 135 lower. Engine is running at normal temperature and is now popping for some strange reason. Check out the video. Plugs are brand new and clean, mixture is new gas and 50 to one, I have some Seafoam in the tank to clean the carbs. Not sure if this is ignition, or a lean condition? any suggestions?

 

[F_R]

running out of gas?

 

[racerone]

Both throttle plates closed at idle ?

 

[flashback]

Water in fuel?

 

[tphoyt]

The sea foam may have loosened up some crud.

 

[jimmbo]

And no one is touching the Throttle?

 

[Mystic Mariner]

And no one is touching the Throttle?

Nope, throttle set just above idle to keep it running. Popping and farting like crazy. I ordered a fuel pump rebuild kit, I have all new Tygon fuel lines and the filters are all clear.

 

[Mystic Mariner]

Water in fuel?

Brand new fuel and oil.

 

[Mystic Mariner]

Both throttle plates closed at idle ?

Yes, adjusted both carbs also for closed at idle and horizontal plates for wide open throttle.

 

[jimmbo]

Did it run before you replaced the Head Gasket?
When you had the Head off, did you check it for Warpage, and/or Lap it?
You say the carbs are fully closed at Idle, are they still fully closed at "just above Idle"?

 

[Mystic Mariner]

Did it run before you replaced the Head Gasket?
When you had the Head off, did you check it for Warpage, and/or Lap it?
You say the carbs are fully closed at Idle, are they still fully closed at "just above Idle"?

Head was slightly warped; had it resurfaced. Ran good considering compression was low on one cylinder due to the leaky gasket. When the video was taken the motor was off idle and throttle plates were slightly open at about 1200 rpm.

 

[jimmbo]

@1200 rpm, they should still be fully closed

 

[Mystic Mariner]

Hello, working on my J45RCLEIA commercial outboard. The Seloc manual mentions adjusting the idle mixture; but...mine does not seem to have one. See the exploded view below. My carbs don't seem to have any mixture adjustment screws? Both carbs are the same except for the roller-follower, it's on the bottom carb and there is synch-linkage to the top carb.

 

[jimmbo]

You just gave an Example of why having the engine specific Service Manual is important

 

[racerone]

Is item #7 in place.-----I think you need to put the boat into the lake and test run.----I think throttle plates are open too early.----If that is the case the idle circuit in the carburetors does NOT work.

 

[Mystic Mariner]

Rebuilt the fuel pump; no more popping.

 

[F_R]

Rebuilt the fuel pump; no more popping.

Post #2

 

[Mystic Mariner]

Post #2

No, not running out. Inconsistent fuel pressure.

 

[Ronniewhite]

No, not running out. Inconsistent fuel pressure.

Same ****

 

[Mystic Mariner]

Same ****

No