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720 carb running rich


S..till T..imeless

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Hitachi (stock) or Weber? Nope don't know a carb guy. I would still recommend that you figure it out. It's gonna go a lot easier and be significantly more enjoyable if you can figure out maintenance and stuff out because paying somebody else doesn't always work out.

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Looks like an '85 in the avatar. California would be the ECC carb with O2 sensor and the 6 wire round electrical plug at the back.

 

I have to assume this is a rich smell... at idle.  Some things that can cause an over rich idle...

 

 

Float has sunk or stuck or inlet needle valve is obstructed and not closing and the float chamber is over filling and flooding. Look at glass bull's eye on front of carb. Fuel level should be half way up. Look also down the primary barrel while running for gas dripping from the venturi.

 

Choke is on or part on. Take top of air filter off and look when engine fully warmed up. Choke plate should be fully vertical when off.

 

I've seen some pretty dirty air filters in my time but never one that choked the air supply enough to lower the mileage.

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Looks like an '85 in the avatar. California would be the ECC carb with O2 sensor and the 6 wire round electrical plug at the back.

 

I have to assume this is a rich smell... at idle. Some things that can cause an over rich idle...

 

 

Float has sunk or stuck or inlet needle valve is obstructed and not closing and the float chamber is over filling and flooding. Look at glass bull's eye on front of carb. Fuel level should be half way up. Look also down the primary barrel while running for gas dripping from the venturi.

 

Choke is on or part on. Take top of air filter off and look when engine fully warmed up. Choke plate should be fully vertical when off.

 

I've seen some pretty dirty air filters in my time but never one that choked the air supply enough to lower the mileage.

We had one on a 79 C10 that was so clogged up that it wouldn't even run.

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Not in California. It has to pass emission testing doesn't it? Can't replace anything but with stock parts.

 

 

Guess I had better ask now before we go farther. Is your 'carb guy' familiar with carbs or EFI? EFI would have much less tailpipe smell than a carb vehicle. What you smell may be normal for a 720.  

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Float has sunk or stuck or inlet needle valve is obstructed and not closing and the float chamber is over filling and flooding. Look at glass bull's eye on front of carb. Fuel level should be half way up. Look also down the primary barrel while running for gas dripping from the venturi.

 

Choke is on or part on. Take top of air filter off and look when engine fully warmed up. Choke plate should be fully vertical when off.

 

I've seen some pretty dirty air filters in my time but never one that choked the air supply enough to lower the mileage.

 

 

 

Check these first and eliminate the obvious causes.

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