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93 Johnson 175 Faststrike

T

Troy45056

New member
Morning, I need some guidance. I have a lean sneeze during idle in water and at idle speed in gear. Below is what I’ve done thus far.

Rebuilt all 6 carbs with OE kits did not use nylon washer. Made sure all 3 orifice per carb were clean and clear.
Took the carbs back apart 4 times to verify float level, and float drop. I set them all at 22mm.
Flushed all ports with isopropyl
Replaced all 6 carb bowls
Replaced fuel filter and gaskets
Replaced Spark plugs
Checked all gaskets at manifold and carbs with starting fluid, carb and choke cleaner, and LP gas unable to locate any type of vacuum leak.
Thermostat on order
disconnected pickup tube in gas tank to verify no cracks and solid fuel up to fuel pump.
Today will be putting a vacuum tester on fuel pump to ensure pump is good.

My next step is scheduling the local shop to do a complete link sync to verify timing.

is there something I’m missing or something else I should/could check?
 
The throttle plate is part of the carburetor.the lo speed fuel circuit exits the carburetor behind the throttle plates.if you only cleaned the black plastic you haven't cleaned the whole carburetor.
 
Rwbutler said:
The throttle plate is part of the carburetor.the lo speed fuel circuit exits the carburetor behind the throttle plates.if you only cleaned the black plastic you haven't cleaned the whole carburetor.
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So pull all six carbs make sure I leave 1 bolt behind to not disturb the spaghetti gasket and flush all ports? Please excuse my ignorance I followed the book, and watched several videos and none mention cleaning that. I’m taking her today to get the link & sync done once I get it back I’ll tear it apart again.
 
Troy45056 said:
So pull all six carbs make sure I leave 1 bolt behind to not disturb the spaghetti gasket and flush all ports? Please excuse my ignorance I followed the book, and watched several videos and none mention cleaning that. I’m taking her today to get the link & sync done once I get it back I’ll tear it apart again.
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You dont have to tear it all apart again. All you need is can of carb cleaner and safty glasses. Find the idle orfice in front of carb body,with spray straw on carb cleaner in orfice open throttle,spray,watch it exit in throttle body.no spray should come out at plate on side of carb.the other carbs need to look the same.now repeat for off idle orfice.&nbsp; All spray patterns should look the same.<br>
 
**Update**

So I broke down and took my boat to a 35 year Johnson veteran mechanic. Can’t even believe I found him. Anywho, I asked him to diagnose the lean sneeze. Here’s what he found.

Starboard side manifold gasket was split in multiple locations causing air to suck in from cylinder to cylinder and 5 of the 6 check valves were shot. He also found some very slight scoring on the #1 cylinder his words “looks like a piece of gasket was sucked into the cylinder”.

He obviously wanted to hone/bore the cylinder for $2,200. But for a 93’ I just couldn’t see dropping the coin especially seeing it was more of a scuff than a score. So I happily paid him the $411 to replace the manifold gasket, the seals, the check valves, and do a link & sync. Took it to the lake, backed it in fired it up. Still have the sneeze. Took it home, tore down the port side gasket is good all 6 check valves are shot. Question- would the check valves cause the sneeze? I know the scoring is no good but visual inspection doesn’t look bad. It runs perfectly fine once I get out of idle speed. I spoke to the previous owner who happens to be my wife’s uncle and he said he’s had the sneeze almost 10 years and 3 boat mechanics couldn’t diagnose it. Most are convinced it’s carburetors since it’s a lean condition.
 
Another follow up. I took apart the port side and replaced all 6 check valves, the manifold gasket, and the throttle body gasket. Took it to
the lake this morning and I still have the lean sneeze. It will idle in gear and sneeze every couple seconds, once I put it in gear it will die, but I can normally keep it going by hitting the primer button. Also, when I tore it down for S&G’s I tore down the carbs again for like the 10th time everything was perfect on those. Note- each float is level, all drops measured to 22mm, I did not use the nylon washer, all 3 orifice are clean, clear, and intact. I seriously need some guidance I’m at a loss of where to go from here.
 
Did you clean the calibration pockets in the throttle body? What are your low speed screws set at? Were they removed and cleaned? I am pretty sure your motor has them. Are the butterflies on the throttle bodies all closed? Do you have a factory manual for.your motor?
 
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