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Old 03-08-2015, 12:07 AM   #1
domano 68
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Fuel Leak at fuel line front of carb

Got a small fuel leak. Looks to be coming from inbetween the large flange nut and where it mounts to the carb (fuel filter marking). You can see the top of the manifold where it is wet.

Tried to tighten the smaller flange nut on the left but its pretty tight. Didn't want to mess with the larger one until I educated myself here.

Is there really a filter in there? Wondering if this setup was modified and changed since an inline cant filter is located to the left if you follow the line to the left a couple of feet.

Is there an o-ring or gasket that could have gone bad? Just looking for some guidance here on what to do. Thanks in advance!

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1971 C10 127 in wheelbase
Model Number-CS10934
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Last edited by domano 68; 03-08-2015 at 12:17 AM.
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Old 03-08-2015, 12:26 AM   #2
SierraMtns
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Re: Fuel Leak at fuel line front of carb

Yes there is a small filter in there. Remove the fuel line and then remove the big nut and the filter will come out. You want to be careful with the threads. They can get striped out.
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Old 03-08-2015, 12:35 AM   #3
70SBC10BOB
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Re: Fuel Leak at fuel line front of carb

If I remember correctly, if you get a new filter, it comes with a plastic washer gasket.

Bob
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Old 03-08-2015, 01:40 AM   #4
domano 68
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Re: Fuel Leak at fuel line front of carb

Thanks guys.

Since there is a canister fuel filter inline prior to this, is there a filter in this location where it is leaking? I am not familiar with this set up. I will go to a local parts store, request a filter for this year and engine and replace the gasket.
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1971 C10 127 in wheelbase
Model Number-CS10934
Body Type & Seating-Fleetside 8 ft.
Original Factory Price-$2,854
Shipping Weight-3,605 lbs
Total Production-206,313
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Old 03-08-2015, 01:55 AM   #5
SierraMtns
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Re: Fuel Leak at fuel line front of carb

Quote:
Originally Posted by domano 68 View Post
Thanks guys.

Since there is a canister fuel filter inline prior to this, is there a filter in this location where it is leaking? I am not familiar with this set up. I will go to a local parts store, request a filter for this year and engine and replace the gasket.
Yes there is. Look about half way down the page. There is a short and long.

http://cliffshighperformance.com/parts.html#a

Look on the side of your carb for a 6 digit number starting with 70... If the carb is newer then 76 the number will start with 170... It is on the throttle linkage side. Take that number in to your parts house and they should be able to get you the filter.
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Old 03-08-2015, 07:40 AM   #6
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Re: Fuel Leak at fuel line front of carb

It may be leaking at the fuel line flare/nut, looks to be going in at an angle.
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Old 03-08-2015, 09:04 AM   #7
1968aj
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Re: Fuel Leak at fuel line front of carb

SOMETIMES previous owner will leave that filter out when they put a inline filter in. if I remember right the filter is a made to install one way for flow.
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Old 03-08-2015, 09:40 AM   #8
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Re: Fuel Leak at fuel line front of carb

Do get that taken care of quickly and don't drive it until it is. A small leak can suddenly become a big leak. A buddy of mine had a small leak on the family car's carb. The threads were stripped.
He told the wife not to drive it but, you guessed it, she just went down to the corner store and poof. Up in smoke. It burned to the ground. Be careful.
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Old 03-08-2015, 10:30 AM   #9
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Re: Fuel Leak at fuel line front of carb

-
To add to what others have said, the threads are very fine and it is easy to get them cross threaded. I also agree about the fuel line being on an angle. Usually the flare will compensate for a small amount of angle but that looks like quite a bit. Use the filter, I can tell you for a fact that it will catch stuff that the inline filter wont. If the threads are stripped they make a repair kit for it.

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Old 03-09-2015, 04:06 AM   #10
MikeyMan
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Re: Fuel Leak at fuel line front of carb

That area where the large flange nut mounts to the carb (fuel filter marking) is prone to get stripped. The cheap pot metal tends to strip after years of wear and possible over-tightening.

Place a rag on top of the manifold to catch the small amount of fuel that will leak from the line and carb housing. Hold the large flange nut with a wrench (1-inch, I think) and un-screw the small flange nut to remove the fuel line. Then, un-screw the large flange nut from the carb. There should be a filter and a spring in there. Don't loose the spring! There should also be a thin gasket around that large flange nut/filter housing. If there is not a gasket, bring the filter housing to the parts store and get one. That's the spot you're leaking. Put the spring in first, then the fuel filter. Make sure the filter inlet is out from the carb, towards the line-in. Thread that large flange nut/filter housing on carefully by hand. Then tighten with the 1-inch wrench. Be easy, you have to go by feel. Make sure it's tight, but not to the point of stripping the threads in the carb.
Then, get the fuel line exactly straight into that filter housing. You should be able to thread that by hand if the line is not binding. Snug it by hand, then make sure you hold the 1-inch wrench on the filter housing while tightening the small flange nut of the fuel line with another wrench.
If you don't hold the filter housing, it tends to over-tighten and possibly strip when tightening the fuel line nut.

Make sure all connections are tight. Check and inspect for leaks after you start up. Immediately shut down if there are any leaks. Always have a fire extinguisher handy, and maybe the garden hose too!

I have heard about repair kits that basically re-thread the carb body when the filter housing is stripped and sloppy. Personally, I didn't want to do this for fear of getting metal shavings inside my mounted carb.
What I did for my fix, I left the spring and in-carb filter out and used a little J-B Weld around the threads of the filter housing. It's basically glued together, but does not leak anymore. Of course, I run an in-line filter.

Always carry a fire extinguisher! It's better to do burnouts, than burn up
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Old 03-09-2015, 09:20 AM   #11
brown7373
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Re: Fuel Leak at fuel line front of carb

What was said, plus a couple more comments. Sometimes the thin gasket to seal the large inlet fitting is missing or damaged. THAT is what seals the inlet nut, not any amount of Teflon tape on the threads. Or, as MikeyMan said, you could permanently glue it on with JB Weld, but without the filter. Same with the fuel line concerning Teflon tape. The flared line seals to the inlet nut flare mount. If the fuel line is too crooked, like yours appears, it won't contact the inlet nut surface flush and will leak.
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Old 03-09-2015, 07:39 PM   #12
domano 68
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Re: Fuel Leak at fuel line front of carb

Any tips on how to get the fuel line straighter? I have not worked with fuel lines and not sure how to go about bending it.
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1971 C10 127 in wheelbase
Model Number-CS10934
Body Type & Seating-Fleetside 8 ft.
Original Factory Price-$2,854
Shipping Weight-3,605 lbs
Total Production-206,313
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Old 03-09-2015, 07:53 PM   #13
enaberif
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Re: Fuel Leak at fuel line front of carb

Fuel line is super soft and bends super easy. Just found a surface you want to use and bend away or do it by hand.
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