1977 Mercury Black Max 175 bogging out

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Lantz22

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Joined
Aug 10, 2019
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This definitely might be a stupid question but I’m having some trouble. So I purchased a 1977 charger with a 77 black max 175. It idles decent and won’t die at idle under load or in neutral. When I give it some love on the throttle it will sometimes get up to 2,000 RPMS (that’s full throttle under load😳) I’m thinking that the air/fuel ratio is messed up and it is getting to much fuel and bogging it out. I’ve replaced fuel lines, checked fuel pump, replaced primer bulb, inspected carbs and floats (spotless). Anyway I can’t for the life of me figure out how to adjust the carb. I’ve looked at similar carbs and have had no luck. Any help is appreciated. I will be checking the exhaust tomorrow. It also smells super rich on the water.
 
Dukedog

Dukedog

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has it been this way from day one of you havin' tha rig? Or did it jus start doin' it?.. there is no adjustment on tha carbs.. if you took tha carbs apart to clean/inspect and didn't replace all tha gaskets inside and out they normally will fail.. if those are original, they were prone ta have floats that can get fuel soaked also....
 
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Lantz22

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Faztbullet said:
Need to check spark as sounds like one bank down...
Click to expand...

I will replace sparks today. They seem to be okay and I checked them all. It’s hard to diagnose because it only does it under load. And the nearest lake is over an hour away. And it runs 100% fine on muffs.
 
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Lantz22

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Joined
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Messages
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Dukedog said:
has it been this way from day one of you havin' tha rig? Or did it jus start doin' it?.. there is no adjustment on tha carbs.. if you took tha carbs apart to clean/inspect and didn't replace all tha gaskets inside and out they normally will fail.. if those are original, they were prone ta have floats that can get fuel soaked also....
Click to expand...

It’s happened since I bought the rig, I’ve owned it for about a month or so and took the carb apart yesterday. They were spotless and the floats aren’t original. I cleaned them all up (what tiny little bit of dirt was there) and cleaned all gaskets and everything.
 
jimmbo

jimmbo

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Start with a Compression Test, then verify the Spark will jump 7/16" gap on all plug wires. No loss of spark as timing is advanced? Timing advancing, and to the proper Max? Pickup Timing verified when carbs reinstalled(the famous 'Link and Sync')? You had the carbs apart, Floats set correctly? Inlet valve sealing? Fuel getting to carbs? Fuel pump good? Filters clear?
 
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Lantz22

Cadet
Joined
Aug 10, 2019
Messages
12
jimmbo said:
Start with a Compression Test, then verify the Spark will jump 7/16" gap on all plug wires. No loss of spark as timing is advanced? Timing advancing, and to the proper Max? Pickup Timing verified when carbs reinstalled(the famous 'Link and Sync')? You had the carbs apart, Floats set correctly? Inlet valve sealing? Fuel getting to carbs? Fuel pump good? Filters clear?
Click to expand...

Floats are correct, it’s sealing, if I run it with no cover I can see fuel getting to the carb, fuel pump functions perfect, filter is clear. Working on compression and sparks today
 
jimmbo

jimmbo

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Running it without the Air Silencer installed isn't the best idea. Seeing some fuel spray shows the Main Circuits is functioning. Doesn't mean the proper mix is happening, and it means nothing when it comes to the idle and off idle circuits. But I did ask if all the carbs were getting fuel.
 
Faztbullet

Faztbullet

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Mar 2, 2008
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15,931
You need to check and see if all cylinders are firing and jump at least a 1/4min air gap. Sound like you have a stator problem and one side is not firing.
 
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