83 GT150 idling issues, pic & videos help please

[motodave]

j150stlcte - Im thinking I have what most on here call a 'lean sneeze' but not really sure. The motor wouldn't idle at all when I got it, and it does idle for a while now before dying. Some background on the work Ive done:
I have rebuilt all 3 carbs with oem kits. Replaced needles & seats, new floats set to specs, removed every jet cleaned and inspected, verified all factory sizes ,and no dried fuel, varnish, damage to any of them. I have checked and rechecked 4 times in the last month. Linked & sync done, throttle plates are all fully closed at idle, open at same time. The only thing Im not 100% on is the position of the cam roller, it is a little past the center mark of the 1st embossed mark as shown:

The only way I know to change this is advance/retard the timing, which I have not tried.

Rebuilt both fuel pumps and replaced lines, no kinks.
Removed and cleaned boats fuel tanks and replaced the lines, no kinks.
Replaced thermostats and seals.
Replaced all 6 recirc valves with oem, and the hoses. Routed per manual.
Fresh clean fuel at 50:1 Johnson premix.
Adjusting the idle screw raised the idle but did not smooth it out, the rpms jump up and down pretty randomly.
Pumping the primer bulb while idling will choke motor out.
Good spark on all 6, jumps 7/16 gap.
Compression 90-100 on all 6.

Heres a video of idle with and without cover on, please help guys Ill try anything at this point! Thanks!

 

[racerone]

If throttle opens too early it will " sneeze "-----You can give the roller more clearance with the adjustment screw just to the right of the roller.

 

[Bosunsmate]

pumping the primer bulb while idling should not choke motor out, readjust floats and blow carb cleaner down every hole while you are in there checking it comes out somewhere else, its normally not the jets that block, its the little passages in the carb behind the jets or are on their own with no jets

 

[Bosunsmate]

Turn motor off and prime bulb, that way you should be able to see fuel pouring out of the one that is leaking (that can cause your engine to stall a touch as seen in video)

 

[motodave]

Racerone - thanks, from reading the manual I thought the roller should be snug against the cam? I can move it down though and try it. Bosunsmate thank you, not to go back on my statement, but its possible the motor just happened to die when I primed it. I can pump on that bulb a lot and no fuel leaks out of carbs. Should I try and adjust the idle screw up again? How many turns is too much? Thanks to all for giving some direction

 

[Bosunsmate]

Bosunsmate thank you, not to go back on my statement, but its possible the motor just happened to die when I primed it. I can pump on that bulb a lot and no fuel leaks out of carbs. Should I try and adjust the idle screw up again? How many turns is too much? Thanks to all for giving some direction

Try again, if it happens again it isnt a coinicidence.
Doesnt sound like adjusting the idle screw is your problem, you could stick two fingers in each carb throat in turn and seeing if that evens her out in one particular carb.

 

[motodave]

Ah I like the 2 finger trick Brosunsmate, and I will try priming the bulb again 1st thing and see what happens. The motor should idle in neutral around 1000 and in gear about 800 or so correct? Thanks for your help!

 

[Bosunsmate]

Ah I like the 2 finger trick Brosunsmate, and I will try priming the bulb again 1st thing and see what happens. The motor should idle in neutral around 1000 and in gear about 800 or so correct? Thanks for your help!

No worries, not sure about rpm but that sounds about right, just nice and low so it slides into gear easy and also not too low it stalls. I always do it by ear

 

[emdsapmgr]

When the engine is idling, there should be no pressure on the cam roller. Butterflys closed. You should be able to slip a pc of thin paper between the cam and roller at idle. This assures there is no pressure on the butterfly rods. You have to set the idle when the boat is floating normally in the lake. In forward gear. Set the idle to 650-750 rpm's. You can't set it on the trailer. That idle is set by the idle timing. Don't worry about idle timing degrees. Set it to the correct rpm's. All boats are different due to how low the engine sits in the water at idle-back pressures are all different, so the idle degrees are all different-and mean nothing. Follow Bosun's suggestion of blowing carb cleaner down every passage in every carb. Compare the visual spray outflow from each passage with the same passage in the other two carbs. It's the dried fuel gelatin in the passages (that you can't see)-that causes a lean sneeze at idle.

 

[motodave]

Thanks so much all you guys, emdsap I will go back at it on the carbs, will even spring for new jets if I have too, spent too much already so why not. Speaking if spending, got home tonight and found someone stole 2 of my batteries! I'm glad to talk to good, helpful human beings like yourselves, thanks again I will report back when funds allow new power