fuel line question

[76bonanza]

From my sender in my tank (behind seat) it is metal the a small piece of rubber hose then metal out of the cab. My question is what size rubber hose do you rekon that is? Going to replace my sender and want to replace that piece while I am there.

Thanks

[tomatocity]

if you don't get an answer, take a piece of the fuel line to the parts store and they can match it. You can bet NAPA will know the correct size.

[cdowns]

i believe it's 3/8 for an 8chlinder truck

[pjmoreland]

If your truck came originally with an inline 6 engine, then the hose should be 5/16 ID. If it came originally with a V8, then the hose should be 3/8 ID. I wasn't aware of this when I ordered a sender for a '69 I had. I ordered a V8 sender, but the truck was equipped originally with an inline 6. The rigid line I had would not thread into the sender. I went to a local hydraulics supply shop and had them make me a replacement rigid line with the correct fitting and bends in it. They charged me $12.

I don't think there is any safety concern about using rubber hose inside the cab since my '72 has a short segment of rubber hose joining the sender to the metal tube that runs down through the floor (original from the factory).

[Green Machine]

5/16 for 6 banger and 2bbl V'8s (283,307), 4bbl V8 is 3/8.

[76bonanza]

any idea how to tell if it was originally a 6 or 8?

[76bonanza]

Here is a better question I am ordring a new sender my rigid line has the male fitting on it. Looks like he bolted a small piece of metal line to it then cut the fitting off the sender and ran rubber hose. But I am thining if I get the right one now I maybe able to bolt right up. How can I tell short of diassebling the line?

[pjmoreland]

You might try measuring the outer diameter of the rigid line to see if it is 5/16 or 3/8. If your truck was originally equipped with a 6-cylinder engine, then the second digit in your VIN will be an S for six, otherwise it will be an E for eight.

What size wrench fits on the hex fitting on the rigid line?

[Longhorn Man]

your VIN... CS or KS will be an inline... CE or KE would be a V8 (of any size) and CM or KM (GMC only) would be the V-6.

[pjmoreland]

Here's what you don't want to have happen. The rigid line fitting was 5/16, and the sender was 3/8. If I remember correctly, the fitting on the 5/16 OD line takes a 1/2" wrench, and the fitting on a 3/8" line takes a 5/8" wrench. I'm sure someone else will chime in who knows for certain.

[Longhorn Man]

Grab a 3/8 inch wrench. Slide the open end iver the fuel line as if it were a nut. If the wrench is a tight fit, it's a 3/8 inch line. If it is sloppy, then it is 5/16.
You NEED the rubber line at the bottom of the fuel line un or directly under the cab. The cab and frame move independantly of each other, and it is needed for free movement.

[76bonanza]

ok listen to this senerio. PO says he put in new sender, now 2 months later sender leaks from solder joint fuel line and float move around sometimes float gets stuck.

By vin my truck was an eight buy the 3/8 wrench test my line going into sender is tight in 3/8 wrench, line from floor is loose. So PO buys sender for 8 cylinder because that is what vin says gets it, it does not fit, cuts off fitting on sender rigs up rubber hose. In process destroys solder joint on sender. Sells truck to me.

So along the way some one took that in cab rigid line from a 6 and used it in the rebuild of the eight. Does this sound like it could happen?

So I should order sender for the six cylinder is what you guys are saying? Or do I need to replace the line to get more fuel flow or will it matter?

Thanks

[76bonanza]

Looking in chevy duty the sell fuel line for v-8 in both sizes so I guess it wont hurt performance.

[Sweet72]

My 72 with 307 had (from assembly plant) 5/16 sender and hard line with a short piece of hose between. I've never seen one with a flare fitting like in the pic above???

[pjmoreland]

Today 12:49 PM
Green Machine -- 5/16 for 6 banger and 2bbl V'8s (283,307), 4bbl V8 is 3/8.

Maybe your truck had a 2bbl V8 originally and that's why it has the 5/16" line.

[76bonanza]

True, question is now I am running a 350 with 4bbl 750 holly should I just get the sender for the 6 cylinder or should I look at replacing the fuel line front to back? I guess what I am getting at from a performance stand point am I hurting performance with the smaller line?

sweet 72 71 and up uses the rubber line from the factory.

Thanks

[Longhorn Man]

5/16 should be fine in all reality, but going to 3/8 would not be hard once the sending unit was replaced. I bent lines up on the Longhorn becouse some idiot used copper tubing. I bent them up nice and pretty and all, and it was simple.

[76bonanza]

I am hoping in about 1-2 years moving the tank under bed any way and may do it then but now just want to fix leaking sender. But dont want to starve the engine either.

So the only difference between the 6 and 8 cylinder sender is the line size?

Also chevy duty has the senders for 29.95 much cheaper than any one else are they junk or same just cheaper?

[76bonanza]

Can someone confirm for sure the only diference in the 6 and 8 cylinder senders is the fuel supply line size. And if I have 5/16 supply line I need the 6 cylinder sender.
Just want to make sure before I order. Also the senders from chevy duty are 29.95 much cheaper then the rest are they an ok company? Just dont want to get junk.

[pjmoreland]

If I were you, I'd order a 6 cylinder sender.

[76bonanza]

ordered my sender today from chevy duty. When I bolt it to the line do I need to use any teflon tape and how tight really really tight or just normal tight?

Thanks for all your guys help.

[Sweet72]

You'll be fine with the I6 5/16 lines unless you plan on feeding a thirsty big block. Don't go real tight on the flare fittings or you'll deform them and end up with a leak. NO, don't use teflon tape, that's only for pipe thread.

[76bonanza]

well replaced sender today, had to do a little bending of the fuel line to get it to line up with sender right, PO must have bent it to make it work for his rubber line setup. anyway good to go no rattling reading good and not leaking when tank is full so all good.
Thanks for all your help