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1977 620 - How to replace/splice torn nylon fuel line right above tank?


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Can't see pic, but assuming you have the wire and bolt hose clamp. I have the same issue. Can't fill over 8-ish gallons to be safe or else I spill. I picked up 1/4" fuel line (about 2', cut to fit) and quick connection hose clamps (use of pliers to get on/off, 5/16"-5/8" assorted). The hose that tore on mine is top of fuel tank to reserve? tank. I have NOT tried the fix yet but hopefully some long needle nose pliers, phillips, razor blade, taking the tire off will fix it. I can try to post pics and update this upcoming weekend. Best of luck!

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3 hours ago, Shortbed said:

Can't see pic, but assuming you have the wire and bolt hose clamp. I have the same issue. Can't fill over 8-ish gallons to be safe or else I spill. I picked up 1/4" fuel line (about 2', cut to fit) and quick connection hose clamps (use of pliers to get on/off, 5/16"-5/8" assorted). The hose that tore on mine is top of fuel tank to reserve? tank. I have NOT tried the fix yet but hopefully some long needle nose pliers, phillips, razor blade, taking the tire off will fix it. I can try to post pics and update this upcoming weekend. Best of luck!


Thanks for sharing your approach. Sounds like the same issue I have. I’ll post my experience and look for yours as well — I’ll have it jacked up in the driveway and tire off this weekend! Will research quick connection hose clamps as there isn’t space in there to work with the pressure union joint you see in the fuel line repair videos. 

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How to replace the hose? Remove the old one and install a new one.

 

It may be hard to get to, but with some persistence and a couple different tools, you should be able to do it in the truck. FIrst thing I'd do is scrub all the junk off so it doesn't get in the tank after you get the old hose off. Use a big nasty wire brush and maybe a flat screwdriver to loosen up all that crud. Spray the hose clamp with WD40 before you try to loosen it. Once you get the clamp loose, remove it and slit the hose with a utility knife. Be careful not to cut too hard though, as it could scar the nipple on the tank.

 

That's removal. Installation is simply a matter of getting good quality hose. With today's fuels, some hoses will break down in months. Ever search for SAE specs? You can find the exact hose specs by doing a google search for SAE fuel hose standards. Why is this important? Because auto parts stores don't know everything and they'll sell you what they have on hand, even if it's not great quality.

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2 hours ago, Stoffregen Motorsports said:

How to replace the hose? Remove the old one and install a new one.

 

It may be hard to get to, but with some persistence and a couple different tools, you should be able to do it in the truck. FIrst thing I'd do is scrub all the junk off so it doesn't get in the tank after you get the old hose off. Use a big nasty wire brush and maybe a flat screwdriver to loosen up all that crud. Spray the hose clamp with WD40 before you try to loosen it. Once you get the clamp loose, remove it and slit the hose with a utility knife. Be careful not to cut too hard though, as it could scar the nipple on the tank.

 

That's removal. Installation is simply a matter of getting good quality hose. With today's fuels, some hoses will break down in months. Ever search for SAE specs? You can find the exact hose specs by doing a google search for SAE fuel hose standards. Why is this important? Because auto parts stores don't know everything and they'll sell you what they have on hand, even if it's not great quality.


thank you Stoffregen! I haven’t been on message boards since the 00’s but this kind of neighborly helping hand is a real breath of fresh air in internet discourse. Your information is useful and much appreciated.  

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1 hour ago, EDM620 said:

E85 is a bit nasty, prevalent where you're located? Tends to varnish/gum up faster

 

Never bought that stuff in my life, but good to know! I'm in Portland and this thing tends to get 87-92 depending on if I'm babying it for some reason. 

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1 hour ago, EDM620 said:

I do believe if recall correctly, that hose should be to the evap cannister. A definate direct line into your tank so replace it for sure & reconnect it

Evap cannister -- didn't know about that. What little I do know about the 620 tank is from this one schematic you can find online: 

https://tinyurl.com/spasdhar

Is that on this diagram? So the hose I'm replacing is at the rear portion of the tank, on top. I guess where Line 30 on that diagram attaches to the receiver elbow that's closest to it. 

Thanks again EDM! 

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2 hours ago, Stoffregen Motorsports said:

I don't see an evap can, but I do see a vapor expansion tank. These are actually kind of important, if you don't like fuel splashing in your face when you remove the fuel cap.

Time to learn a little basic hydrostatics / automotive engineering! This Datsun keeps on giving. Thanks again Stoffregen! 

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23 hours ago, Stoffregen Motorsports said:

evap can, but I do see a vapor expansion tank.

These are essentially the same thing, different naming. The fuel vapours from the tank are drawn up into the evap cannister (essentially a big plastic cylinder that is stuffed with carbon foam and open at the bottom) where those vapours can be drawn into the manifold/carb through engine vacuum. Yes a benefit is also not having your gas tank pressurize and spewing fuel into your face. 

Evaporative Emission Control System

 

Typically found in the engine bay, the round or sometimes sqaured cannister will have 3 hoses connected to it. On your 620 it should be located effectively behind the left headlights 

Evap canister / Emissions pressure test - Chevrolet Forum - Chevy  Enthusiasts Forums

 

Like having a functioning EGR (exhaust gas recycler) valve, it is a benign system that has zero affect on power - as in you won't gain any be removing it - but your vehicle will run better and cleaner internally. Sure, they ain't pretty so often get removed because of appearance, or lack of understanding.

 

If yours is missing, every car in the wrecking yard will have a donor, choose one that you can fit.

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EVAP cans get clogged with age. So I would never buy a used one unless I could verify that it works. Cheap aftermarket ones are readily available.

 

It is possible to cut an EVAP can apart, replace the charcoal and filter and then plastic weld the can back together, but wasted effort in my opinion.

 

Also, vapor expansion tanks are not normally vented to atmosphere, while EVAP cans are.

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  • 2 weeks later...

@Onstad hopefully you can see the pics. Self explanatory I think. Phillips #2, lineman pliers, 10mm wrench. I cut the hose a little short, may be revisiting later lol hopefully this helps. Ill see if I spill gas at next fill up, not entirely too sure about the quick hose clamps.

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