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Fuel not getting to the carb when priming. Whats the symptom?

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Old 12-09-2007, 02:45 PM
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mpr86
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Default Fuel not getting to the carb when priming. Whats the symptom?

I posted here a few days ago, I am having lots of problems getting the idle on the car correct, and it's impossible to tune...

I went to go test something out right now...

Everything connected normally, I attempt to prime the engine by holding my finger over the exhaust. NO fuel comes through the fuel line to the carb. The second I take the fuel line off the carb, and put my finger over the exhaust again, fuel flows perfectly. I have also cleaned the entire carb out as requested by Traxxas tech support. Can this be my fuel tank? The top of the tank, where the nipple comes out of is a darker white color, as if there has been a lot of stress on that point. Maybe a leak? Any other ideas?

Thanks

Edit: So I took out the HSN needle, attempted to prime. And fuel flows perfectly. I cleaned the HSN and allowed a bunch of fuel to flow through the carb and out of the HSN. I re-insert the HSN, and still having same problem.
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Old 12-09-2007, 03:05 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

sounds like theres dirt in the hsn tap or theres a crack in the fuel tank or split fuel line . for a cracked tank - block off the ends with fuel line so no fuel can come on or out . and put it in a bowl of water and see if bubbles come out the thank and fuel line replace if you have some new fuel line and for the hsn take the carb compelty and flush it though about 6-8 times and rebuild and see if that works (make sure all tapes are tight)
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Old 12-09-2007, 03:05 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

check to see if there is anything blocking the fuel intake post on the carb...either there is a plug there or its getting some preasure but not enough. it could be the fuel tank. i would take all the lines and the tank off the truck submerge the lines and tank and blow into one end and hold your finger over the other. if there is any bubbles then you have a tank or line leak. if its not that i would soak your pipe in hot soapy water with some degreaser in it and try and clean the nipple on the side of it where the fuel line goes into. you might be able to get away with just spraying some WD40 in there and trying to blow it out with compressed air.
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Old 12-09-2007, 03:29 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

Ok I submerged the fuel tank in a bowl of water. No bubbles, tried blowing through one end and blocking the other with my finger. I also line a line between the the two nipples still no bubbles. I guess I will try the exhaust and carb next
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Old 12-09-2007, 03:47 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

ok take of you fuel tank and where the fuel goes in to the carb put some fuel line on and blow down the fuel line in to the carb is it ver hard to blow down ?
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Old 12-09-2007, 04:26 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

if the fuel isn't getting to the carb i jsut had this problem. check to make sure that the nipple that goes into the carb is lined up with the hole in the hsn. if it isn't then the fuel can't get to the carb
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Old 12-09-2007, 04:27 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

Yes, Very difficult to blow air from the fuel line into the fuel nipple on the carb. I barely can hear air passing through it.

Must be the carb then? Maybe something is blocking it
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Old 12-09-2007, 04:50 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

ORIGINAL: cmerritt

if the fuel isn't getting to the carb i jsut had this problem. check to make sure that the nipple that goes into the carb is lined up with the hole in the hsn. if it isn't then the fuel can't get to the carb
x2
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Old 12-09-2007, 05:11 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

right ok try and tighten it up a little bit just a little bit not too much or you will shear the nut off .if still hard to blow try the low speed needel it might be screwd in to far . open the carb and try agin
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Old 12-10-2007, 05:20 AM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

Stupid question here, but since I have actually done it I'll ask anyway. Is the HSN screwd all the way in?
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Old 12-10-2007, 02:34 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

^^^as stupid as that could be im guessing that might be the problem.
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Old 12-10-2007, 03:06 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

sounds stupid, but if your not a good engine tuner or just careless when your cleaning it can happen. ive also left the litlle clip on the fuel line closed, so if you have one of those make sure its open. you sure its not the fuel line itself? take it off the tank and carb then blow through...it might be clogged
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Old 12-10-2007, 03:28 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

usually if its a clear line you can see if their is any blockage...i could see him taking th HSN out and cleaning it and then screwing it all the way back in forgetting that it should be turned out about 4 turns from tight. just a brain fart. that would cause all the symptoms hes talking about.
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Old 12-10-2007, 04:55 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?

Check BOTH needles. Sounds like the LSN is screwed down also.The LSN setting affects the total fuel flow thru the carb. The screw head on the LSN should be flush with the housing for factory break-in spec. Actual post-breakin setting will be close to that, usually within a quarter turn.
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Old 12-10-2007, 04:57 PM
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Default RE: Fuel not getting to the carb when priming. Whats the symptom?


[quote]ORIGINAL: nitrorcjunkie

Check BOTH needles. Sounds like the LSN is screwed down also.The LSN setting affects the total fuel flow thru the carb. The screw head on the LSN should be flush with the housing for factory break-in spec. Actual post-breakin setting will be close to that, usually within a quarter turn.
You should be able to blow into the fuel line and hear air no matter what the HSN is set at.
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