Carb to Fuel Pump Hard Line [Leak at Fuel Pump]

[Rich72C10]

My current hard line is a bit tired from previous owners not likely using a flare nut wrench and also looks like the line has been bent around a few times too. I bought a hard line from Summit Racing, actually this is my second one and the best I can get it is perhaps 2~3 drops a second of leakage. I tried the lapping method for over 30 minutes, never got it better than the 2~3 drops a second. Both of the lines I got from Summit Racing acted the same way.

So I am giving up on Summit and have ordered one from GMCPaul's and put the old one back on. I thought I bought the steel line but I see from my email confirmation I got the stainless steel one.

I know these lines do not take any sealer, tape, dope, etc. Any other tips out there for when I get my GMCPaul's line in? Should I also reach out to GMCPaul's to switch the stainless steel to regular steel one?

Thanks for helping me NOT setting my trunk on fire

GMCPaul's

Pump To Carb Stainless Steel Line SB V8 W/Long Pump & A/C
1971-72 1/2 & 3/4 Ton truck, Suburban, Blazer / Jimmy 2 wheel drive fuel pump to carburetor line V8 350ci manufactured in stainless steel and CNC bent exactly like original, for 350ci motor with long bowl fuel pump & A/C.
Proudly Made In the USA

[tdangle]

You don't need tape on the threads. The seal is created at the flare. Maybe the mating surface on the fuel pump is nicked causing all the lines to leak. Fuel pumps are cheap if that's the answer

[Rich72C10]

agreed, about tape/sealer. The old line doesn't leak like the others, though perhaps it has mated itself up to the fuel pump "nick" - if that is where the problem is at.

Other than O'Rileys and such - any recommendations, so I can be looking into that too - if need be?

[truckster]

Originally Posted by Rich72C10

agreed, about tape/sealer. The old line doesn't leak like the others, though perhaps it has mated itself up to the fuel pump "nick" - if that is where the problem is at.

Other than O'Rileys and such - any recommendations, so I can be looking into that too - if need be?

I bought mine (Delphi) from Rockauto.com.

[Rich72C10]

having problems finding mine. I see there are short and long, then 2 or 3 lines. Mine looks like a short 3 line fuel pump but I cannot find one.


Edit: So perhaps a previous owner put this on that goes to something like a Nova? Any site I go to its either a short two line or a long 3 line. There are no short 3-line fuel pumps that are called out for a 72 C10 SBC350 - that I can find. Rock Auto, O'Riley's, AutoZone Advance Auto Parts. So mine has to be wrong?

[Andy4639]

This it? Picture looks the same.
1972-1974 Chevrolet C10 Pickup Fuel Pump Carter

https://www.partsgeek.com/gbproducts...QaAtS6EALw_wcB

[BRL]

Put one of those chrome duel feed hard lines to both float chambers.

After going back to the store for an exchange, they both leaked like crazy!

Finally applied thread tape to the fittings and that solved the problem.

[Rich72C10]

Hi Andy,

That is what I am more or less looking at on RockAuto (and other sites) for a 3-line Fuel pump for a 72 C10 350. I am pretty sure that lower can is longer than what is installed on my C10 with a 3-line hookup.

On my 72 truck (the way I got it) it has a Short 3-line Fuel pump but all the short ones are 2-Lines (for a C10 72). Parts store list only a Long Fuel pump for 3-lines. Sticking with Delphi, this is a part number of MF0055 on RockAuto.

Since clearly they make a Short 3-Line Fuel Pump and I found it on RockAuto for a 72 Nova but it is also called out for a 73 C10. This Delphi part number is MF0002.

I looked at my Chevy manuals and I only found one place about the Fuel Pump and it was only a few pages long and only showed the short two line version.

[Andy4639]

Originally Posted by Rich72C10

Hi Andy,

That is what I am more or less looking at on RockAuto (and other sites) for a 3-line Fuel pump for a 72 C10 350. I am pretty sure that lower can is longer than what is installed on my C10 with a 3-line hookup.

On my 72 truck (the way I got it) it has a Short 3-line Fuel pump but all the short ones are 2-Lines (for a C10 72). Parts store list only a Long Fuel pump for 3-lines. Sticking with Delphi, this is a part number of MF0055 on RockAuto.

Since clearly they make a Short 3-Line Fuel Pump and I found it on RockAuto for a 72 Nova but it is also called out for a 73 C10. This Delphi part number is MF0002.

I looked at my Chevy manuals and I only found one place about the Fuel Pump and it was only a few pages long and only showed the short two line version.

The 71-72 had the emission stuff on them that maybe what the third line is for.

[Andy4639]

Summit has them. For all small block motor no matter what the vehicle is. They all will work.

https://www.summitracing.com/parts/c...8aAvZXEALw_wcB

[Rich72C10]

that is one big photo!

Yep, I can see how to get one for sure and I am 100% sure you are correct about the emission stuff with the 3-line.

What took me down this rabbit hole was ordering from GMCPauls the correct hard fuel line between carb and fuel pump. He has quite a few options for a 350. Long, Short, with or without A/C. The thing is, Paul doesn't have one listed for Short Fuel Pump with A/C.

I just clicked away and ordered a "Pump To Carb Stainless Steel Line SB V8 W/Long Pump & A/C listed for 1971-72". Then I thought, wait, my pump didn't seem very "Long" how could it be shorter??? So this is where I am at now.... Get the wrong line, it will not route right and be too short.

Anyways, I am fussing about getting the correct pump and hard line - might as do it correctly (is what I been thinking).

[Andy4639]

Originally Posted by Rich72C10

that is one big photo!

Yep, I can see how to get one for sure and I am 100% sure you are correct about the emission stuff with the 3-line.

What took me down this rabbit hole was ordering from GMCPauls the correct hard fuel line between carb and fuel pump. He has quite a few options for a 350. Long, Short, with or without A/C. The thing is, Paul doesn't have one listed for Short Fuel Pump with A/C.

I just clicked away and ordered a "Pump To Carb Stainless Steel Line SB V8 W/Long Pump & A/C listed for 1971-72". Then I thought, wait, my pump didn't seem very "Long" how could it be shorter??? So this is where I am at now.... Get the wrong line, it will not route right and be too short.

Anyways, I am fussing about getting the correct pump and hard line - might as do it correctly (is what I been thinking).

Yea that is correct you will need the right one. Are you going hard line all the way to the carburetor? If not just cut the top off and put a half flare on it and rubber gas line with a in line filter call it good.

[Rich72C10]

Yes, hardline from Pump to Qjet 4BB.

So it seems if I get the one that I actually ordered from GMCPaul's (hardline that is), a 72 3-Line Long Fuel Pump is in order... or at least that is how I am reading the tea leaves.

Really wished I knew how it got a short fuel pump or if there was some last moment change with the 72 C10 Emissions (fuel vapor canister lines) where they sub the 3-line long with a 3-line short. They are surely around for 72 (on the Nova, Monte Carlo and then starting for the 73 C10).

Ugh I hate when things don't line up, really kicks in my OCD!

[Rich72C10]

Another note, if going to a 3-Line Long Fuel Pump, it would be about 1 1/2 longer (closer to the ground). That is going by Delphi dimensions of 4.5 x 3.5 x 6 inches (Short MF0002) and 4.2 x 4.2 x 7.5 inches (Long MF0055).

Also the Short is 9 PSI (Average Flow Rating/GP of 40) and the Long is 8 PSI (Average Flow Rating /GP of 65)

Not sure if the PSI/GP is any kind of factor at all. I guess these are not 5 PSI since they are 3-line (I swear I read the carb was suppose to have 5 PSI).

Lastly here is a photo, the lines from the fuel take (hard to soft) appear to match up at the correct level for this Short guy. I'd image there would be a downward slop with the long.... maybe my soft lines would not reach properly?

[Andy4639]

Well if it doesn't work you can go buy the fuel line at auto store and a double flare tool and make your own lines. It's easy enough as long as you take your time making the bends.

I made all the fuel lines and brake lines for the 68 step I built.

[Rich72C10]

Very true, new soft fuel lines would be zero issues.

Creating a hardline, well I'd need a pipe bender and the a double flare tool. Likely something that I'd never use again or pretty sure of that. Plus I am sure there would be a learning curve before I got it right. My skin is already pealing off as it is with today's work LOL

My actual point I was trying to make and I see I wasn't clear at all. If everything appears to line up for a short fuel pump, that seems a lot of work for someone to go through to change from Factory short to long. I guess it is possible when it was restored they made their lines to a short pump they picked up 10 years ago... Basically its just me trying to solve the 3-Line short fuel pump that appears to be out of place/time with my C10. waaaaa

[dmjlambert]

Originally Posted by Rich72C10

...I bought a hard line from Summit Racing, actually this is my second one and the best I can get it is perhaps 2~3 drops a second of leakage. I tried the lapping method for over 30 minutes, never got it better than the 2~3 drops a second. Both of the lines I got from Summit Racing acted the same way.

Does this remain the problem? You have a hard line you would like to use and you attach the hard line and snug it up and it leaks? This is my solution, no more leaks. Copper flare gaskets. I'll never install another hard line at the pump, nor re-attach the hard line to the carburetor after changing the filter, without using one. Easy, cheap, pain free. https://67-72chevytrucks.com/vboard/...d.php?t=762179

[Rich72C10]

Originally Posted by dmjlambert

Does this remain the problem? You have a hard line you would like to use and you attach the hard line and snug it up and it leaks? This is my solution, no more leaks. Copper flare gaskets. I'll never install another hard line at the pump, nor re-attach the hard line to the carburetor after changing the filter, without using one. Easy, cheap, pain free. https://67-72chevytrucks.com/vboard/...d.php?t=762179

It looks like you got these from Grainger PARKER Flare Gasket, Flare Connection Type, 3/8 in Tube Size.

Could you explain how you used them? This sounds like a pretty good idea to me.

Originally Posted by Steeveedee

Those are meant for single flare lines, just so you know. But they will conform to the double flare fitting, so it's all good. We used those to seal up single flare fittings on spacecraft fuel systems, which have to not leak for the lifetime of the thing, which might be 30 years or so, like the Hubble (which I did not work on); just pointing out an old system that is still working. If you break the fuel lines open, you should either use new conical washers or anneal the ones you removed in the oven, provided they are not dented. If dented, just toss them. Do know, however, that many millions of vehicles rolled off the assembly without washers in the fittings.

And this single flare washer to the double flare is no issue at all?

Edit
Found this interesting fellow talk about "How to make a flare fitting copper washer to seal a seeping fuel line" on YouTube. I think I get how to use the ones from Grander now...

[Rich72C10]

At the moment, no. I put the old line back in. I'll check out your link, thanks! Though I do have to get it pretty tight, more so than I would like!

[dmjlambert]

Yes that's the part number 5WRW3. You just insert them in the flare fitting. Sandwich one between the steel surfaces of the tube and fitting. When you tighten it up you will only need to tighten a reasonable amount. I think they are pretty wonderful. Without using these gaskets, I tightened the connection at the fuel pump, and tightened it more, and tightened it more and more until finally I had no leak. There was no way to get the connection loose again without destroying the fuel pump. I'm surprised I didn't destroy the fuel pump putting it on. It takes more finesse and patience than I have to mate the steel surfaces and get them to not leak. Now that I have a box of these gaskets, I can whistle while I work, instead of grunting and cussing.

[dmjlambert]

More info: With the copper gasket I found it was not necessary to do the tightening and loosening and re-tightening procedure to get it to seal, and I have reused the same gasket a couple of times with no problem. If I get a hint of a leak or if the gasket looks scarred, then I use a new gasket. I don't know how to describe how tight the connection needs to be, because I didn't use a torque wrench. I don't think it needs to be very tight, just snug to the point I'm sure it won't vibrate loose.

[Rich72C10]

So the pointy end goes towards the fuel pump and you don’t need to do a cycle of tighten/loosen before the final snug down?


Edit
I posted this before I saw you newest posting on not doing the cycling back and forth.

[Andy4639]

I've never seen those. I watched the video and after watching it I wonder if you could buy a box of brake banjo fittings that would do the same thing. Just a thought. They are copper and thin and made to seal up brake hoses.
This picture they look to thick though & to big.

[Rich72C10]

i am thinking more like this? Not that I have the proper tools to do it...

110pc Copper Washer Assortment Flat Ring Oil Brake Line SAE

[geezer#99]

Those flat washers are the wrong shape.
You need a cone shape to seal.