Carb Fuel Leak, need help. - Team Camaro Tech
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post #1 of 13 (permalink) Old Mar 15th, 10, 04:04 PM Thread Starter
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John
 
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Carb Fuel Leak, need help.

Hi guys. I noticed this weekend that I had a bit of gas dripping from my carb onto my intake. I went around and tightened all of the bolts but I still seem to have small leak coming from the underside of the carb. I've taken a couple pics. I don't have any experience working with carbs so I don't know if this is something that I can fix.



I took another pic with a mirror under the carb... it appears to be pooling under the little arm.



I don't want to take any chances when it come to fuel.

Thanks for having a look. I appreciate your help.
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post #2 of 13 (permalink) Old Mar 15th, 10, 04:13 PM
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Wink Re: Carb Fuel Leak, need help.

Either the screws are slightly loose (easy fix)
Ot - the diaphram in the accelerator pump has failed (harder fix)
The diaphram is under pressure as you press the throttle - so they leak very badly when they fail.
If the diaphram failed you will need to buy the correct one and replace it.

You can disconnect the fuel inlet line and remove the fuel bowl to get to it and replace.
Plan on a new bowl gasket also unless you used 'serviceable' ones originally ...

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post #3 of 13 (permalink) Old Mar 15th, 10, 04:21 PM
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Re: Carb Fuel Leak, need help.

That is Typical of Carburetor Engines that have been sitting and particularly Holley's as they have big Gasket Area's. After sitting around for a month or 2, I always tighten the Fuel Feed Lines and Re-Torque the Carb Base and Bowls before starting the Engine; even then, I keep the Hood Open with Fire Extinguisher handy just in case there is a Fuel Leak ;o)

If you store your car during the winter months, it's a good Idea to crack the Fuel Bowls a Drain the Gas from them and spray some Rust Check into the Air Vents to lubricate and prevent Oxidation in the Bowls. To days Gas is bad for Oxidation.

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post #4 of 13 (permalink) Old Mar 15th, 10, 04:46 PM
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Re: Carb Fuel Leak, need help.

Looks to me like it could be coming from the red fuel inlet plug based on the dirt around the bowl screw.. Try and gently tighten that as well as the bowl screws.


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post #5 of 13 (permalink) Old Mar 15th, 10, 04:56 PM
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Re: Carb Fuel Leak, need help.

Also try a dry tissue rolled up into a point. Then touch it to the highest spot of the carb that you suspect leaking. Look for fuel. If dry, work your way down looking for fuel. Might work. Or fuel could be coming from another high spot and dripping from the low spot. I hate carbs.
Also, that's a pretty spotless looking ride there. How about a wide angle shot?

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post #6 of 13 (permalink) Old Mar 15th, 10, 05:20 PM Thread Starter
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Re: Carb Fuel Leak, need help.

Thank you for your replies... I went out and had another look. It appears that the leaking is coming from these two screws. I tightened the heck out of them but I think that they are still leaking from here. Are there gaskets or o-rings on these plugs? What are they? I slightly moved them a fraction of an inch backwards and the fuel went everywhere.

Also, do you guys know of a chart somewhere that lists what diaphrams go with what Carbs? It's a Holley 870CFM Hardcore. Thanks!

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post #7 of 13 (permalink) Old Mar 15th, 10, 05:34 PM
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Re: Carb Fuel Leak, need help.

Those are for replacing the jets without removing the bowls, you need to replaced the gaskets on them.

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post #8 of 13 (permalink) Old Mar 15th, 10, 05:58 PM Thread Starter
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Re: Carb Fuel Leak, need help.

Quote:
Originally Posted by Dan E. View Post
Those are for replacing the jets without removing the bowls, you need to replaced the gaskets on them.

Dan E.
69 SS396 4spd. 4.10 posi. x66 coupe
Thanks Dan,

Found them on Holley's site. "fuel bowl sight plug and gasket kit". This is officially the cheapest reapir I've made on the car ever....knock on wood. Thanks again guys. I'll post back if that stops the leak. I may still need to replace the diaphram too.
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post #9 of 13 (permalink) Old Mar 15th, 10, 06:37 PM Thread Starter
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Re: Carb Fuel Leak, need help.

Does anyone know what kind of diaphragm I should order? It's a Holley 4150 870 CFM. I don't know if I should order the GFLT or the rubber one. Thanks! I use pump gas but most of that is at least 10% ethanol here in Missouri.
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post #10 of 13 (permalink) Old Mar 15th, 10, 06:45 PM
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Re: Carb Fuel Leak, need help.

Quote:
Originally Posted by johnnymac View Post
Thanks Dan,

Found them on Holley's site. "fuel bowl sight plug and gasket kit". This is officially the cheapest reapir I've made on the car ever....knock on wood. Thanks again guys. I'll post back if that stops the leak. I may still need to replace the diaphram too.
John, that's the wrong gaskets. You need the ones for the "Quick change bowl plugs". They are slightly bigger.

http://www.holley.com/108-77.asp

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post #11 of 13 (permalink) Old Mar 16th, 10, 01:08 PM
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Re: Carb Fuel Leak, need help.

Quote:
Originally Posted by ZZ430DropTop67RS View Post
John, that's the wrong gaskets. You need the ones for the "Quick change bowl plugs". They are slightly bigger.

http://www.holley.com/108-77.asp

Correct - "Quick Change" bowl plug gasket = #108-77

You don't need the GFLT type parts unless you're running Alcohol based fuels.
Looks like you're running 30cc pump, so the Holley #135-5 is most likely the pump diaphram you need.

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post #12 of 13 (permalink) Old Mar 16th, 10, 01:11 PM Thread Starter
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Re: Carb Fuel Leak, need help.

Thank you!! now I just need to figure out how to remove the nickel sized staint that the fuel drips left on my polished aluminum intake....
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post #13 of 13 (permalink) Old Mar 16th, 10, 03:55 PM
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Re: Carb Fuel Leak, need help.

John, REAL ENGINES use gasoline. A drip-spot is OK. But nitrous is cheating. I'd be hiding that system.

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