SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: Brad @ SCJB on August 17, 2015, 08:07:48 PM
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I have a demon 850 vac secondary carb. I did a quick rebuild on it. New gaskets, needle/seats, etc. I put it back on the boat and its blowing out tons of black smoke (unburnt fuel). I noticed its now dumping a ton of fuel during idle where it wasn't before. Float levels are fine and jet sizes weren't changed. Idle set screws are 1.5 turns out on all 4 corners.
What did I screw up?
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Looks like you are missing the back squirter?
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Double gasket the power valve?
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Looks like you are missing the back squirter?
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No squirt nozzles on the secondaries on a vacuum secondary carburetor.
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What series is it? I have a demon book I can look up all the stock specs for you. It's a VS with annular boosters and an 850 right?
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I have a demon 850 vac secondary carb. I did a quick rebuild on it. New gaskets, needle/seats, etc. I put it back on the boat and its blowing out tons of black smoke (unburnt fuel). I noticed its now dumping a ton of fuel during idle where it wasn't before. Float levels are fine and jet sizes weren't changed. Idle set screws are 1.5 turns out on all 4 corners.
What did I screw up?
Never mind. I think you installed the wrong metering block gasket. Hopefully you kept the old ones to compare?
GT
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Yeah that's possible. There was two sets included. I didn't think to look if they were different. Bah.
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Gt might be something they're.
Here's the factory specs for what I believe to be your carb.
On my phone so it's hard to take screenshots and put them together
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I have a demon 850 vac secondary carb. I did a quick rebuild on it. New gaskets, needle/seats, etc. I put it back on the boat and its blowing out tons of black smoke (unburnt fuel). I noticed its now dumping a ton of fuel during idle where it wasn't before. Float levels are fine and jet sizes weren't changed. Idle set screws are 1.5 turns out on all 4 corners.
What did I screw up?
Are you sure the floats are set properly sounds like fuel is just running in. Check all other suggestions
Gt might be something they're.
Here's the factory specs for what I believe to be your carb.
On my phone so it's hard to take screenshots and put them together
Double gasket the power valve?
Sent from my SCH-I545 using SoCal Jet Boats mobile app
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Where is it pouring fuel in? The boosters? Idle slots? Acc pump squirter? (Actually seen that before... Was a trip) Is it pouring in from the front or rear? How did you check your floats? Dry check with a measuring device? Or checked installed, running, with the sight plugs? What kit did you get? Specific to that carb? Or a generic one size fits all with a ton of "extra" gaskets?
This will narrow it down a whole bunch.
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It was a specific kit to this carb I got from summit. It's pouring from (sorry for my lack of technical terms) out of the round ring in the center on the primary side only. The floats have clear sight windows and they are just at the bottom of them. Adjusted only by using those sight windows while running.
Here is the kit I used:
http://m.summitracing.com/parts/DEM-190003
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It was a specific kit to this carb I got from summit. It's pouring from (sorry for my lack of technical terms) out of the round ring in the center on the primary side only. The floats have clear sight windows and they are just at the bottom of them. Adjusted only by using those sight windows while running.
Here is the kit I used:
http://m.summitracing.com/parts/DEM-190003
Check for the wrong metering plate gasket.
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Yup. Sure as shit was the wrong metering block gasket. I had this black one in there. Swapped it for the blue and it worked. Only difference between the two was the blue didn't have the hole just under that square vent hole and had a hole rather than the arch over the power valve cutout.
A side issue I've seen twice now with this carb is I get the brass needle clogged and stuck that's under the squirter. It takes a lot to get it free and its caked with white corrosion. I do have a issue getting water in one tank, so that might be the corrosion issue.
Damn fill cap gaskets are leaking water - I think that's my source of water in this one tank. Any idea where I can replace the rubber in them? Looks like they are just O-rings. Rex even still make these?
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Yup. Sure as shit was the wrong metering block gasket. I had this black one in there. Swapped it for the blue and it worked. Only difference between the two was the blue didn't have the hole just under that square vent hole and had a hole rather than the arch over the power valve cutout.
A side issue I've seen twice now with this carb is I get the brass needle clogged and stuck that's under the squirter. It takes a lot to get it free and its caked with white corrosion. I do have a issue getting water in one tank, so that might be the corrosion issue.
Damn fill cap gaskets are leaking water - I think that's my source of water in this one tank. Any idea where I can replace the rubber in them? Looks like they are just O-rings. Rex even still make these?
Awesome.
As for the corrosion, I always run a little Marvel Mystery Oil in the fuel. About 200:1. It virtually stops corrosion in its tracks.
Take your fuel cap into a NAPA store, if they are worth two shits they can make some o-rings for you.
GT
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i know this is old.....but damn it i like seeing problems solved here......
NICE JOB FELLAS :thumbup: