easiest way to change rubber fuel lines on tank?

[C10Silverado79]

I need to replace the rubber lines coming out of the tank and going down to the hard line along the frame. Mine are very soft and I think they are collapsing under a heavy load. It there a way to do it without dropping the tank or removing the bed?

[silvereagle07]

You will have to drop the tank. They sit under the cab more than the bed.

[tucsonjwt]

I can't see any way to do it without dropping the tank or lifting the bed. I recently changed mine out when I put in new sending units, but I have a dump bed conversion, so I just lifted the bed and replaced them from the top. Here is what they look like on top of the tank, if you have not already seen them. I had 3 hoses (dual tanks, no vapor recovery cannister), and one of the hoses had a vent fitting in it. The vent fitting can be carefully disassembled, cleaned and reassembled. Each of the 3 lines is a different size. I had a bad fuel smell but it mostly went away when I changed the hoses. I think you will always get some fuel smell because of the open vent fitting.

[C10Silverado79]

I found this thread which will help. A lot will depend on how rusted the mounting bolts are. I have a motorcycle jack that I can use to support the tank so I'm not too worried about that.

Does anyone know that the line sizes are for the hoses? I have Fuel - return- and vapor. I saw a thread recently with a pic of a sending unit and the poster mentioned the line sizes but i can't find it again.

tucsonjwt - thanks for the pic. My hard lines run along the inside of the frame and the hoses bend over the frame an attach down inside instead of right under the cab. I don't know if that was stock with my truck or a mod when someone installed an aftermarket secondary tank. Hopefully this will make it a bit easier. I'm going to disconnect the tubing for the second tank while I'm at it and eventually remove the second tank.

[tucsonjwt]

I don't recall the exact sizes of the rubber hoses, but I just took the short pieces off and used my digital caliper to confirm the id of the hoses/od of the hard lines they attached to. I think it was like 3/8", 5/16", and 1/4". Suggest you just do the same and go to the auto store for a foot of each size once you have them off - recommend new radiator clamps also. I posted the sizes here somewhere, but I can't find that post under my screen name now.
Here are a couple more pictures of my setup - I know it is not like yours.

[C10Silverado79]

Thanks,
I'm hoping to have the hose I need so I don't have to run to the parts store in the middle of the job. I don't have a garage and it's difficult to have the truck up on stands for any length of time. I will definitely use new hose clamps. I hate messing with used clamps.

[tucsonjwt]

Since you have a vapor recovery canister and I do not, the line sizes may be different. Heavier trucks like my 3/4 ton C20 were exempt from vapor recovery for a while back when my truck was built (83). Unless you have fairly "fresh" spare hose laying around, I would invest in new fuel hose - you never know when that hose on your workbench is not really fuel line. You're only talking like a less than $8 investment. I bet 1' - 2' of each hose would do it to connect from the senders to the hard lines. You might be able to call the auto parts store and ask them if they know the sizes in advance. The inlet sizes of the sending units will be the same as the other end of the hose that connects to the hard lines/vapor recovery canister line.

[C10Silverado79]

I'm pretty sure from what I've gleaned from some searches that the hoses are:

Fuel - 3/8
Return - 5/16
Vapor - 1/4

I'll probably stop at the parts store on the way home. Then again, I may wait till I get home and check what I have. I replaced the fuel and return lines on the other end when I put on a new fuel pump. I don't know if I have a enough extra to use but I can tell the sizes.

[Prong]

It's actually:
Fuel - 3/8"
Vapor - 5/16"
Return - 1/4"

[C10Silverado79]

Thanks, at least I had the sizes right. Just match them up to what comes off and I should be good to go I guess ... assuming I can get the bolts out. lol

[78 Chevyrado]

Lift the bed. if you drop the tank there's no possible way for the lines to be the proper length and routed properly once you put the tank back.

[79gmcc15]

Also don't use regular rubber lines. Get ones that can handle ethonal. Just because you don't want to be doing it again in a couple years when the ethonal eats through the line.

[DBLSPRT68]

Originally Posted by 78 Chevyrado

Lift the bed. if you drop the tank there's no possible way for the lines to be the proper length and routed properly once you put the tank back.

I've done it both ways. Last time I dropped the tank. What a pain in the A$$. I will NOT do that again! Next time (which will be soon!) I will pick up the bed with my cherry picker and some chain.

[C10Silverado79]

I don't have the equipment or facilities to take the bed off. If I unbolt the front of the bed, it there enough 'give' to jack up the front of the bed a few inches to provide access rather than pulling the bed all the way off? Right now it looks like dropping the tank is my only option.

[tucsonjwt]

Either way is no picnic. To remove the bed you need to remove the bed bolts. Even in dry AZ, I have found that the bed bolts and nuts are caked on mud and some rust - meaning you need some time and liquid wrench/PB blaster to get them off the first time. If you have other plans to remove the bed in the future, then you can go that route now an loosen up the bolts.
I changed sending units once by dropping the tank. I used concrete blocks and pieces of 2 x 4 wood, 1 x wood to snug up against the tank, then removed the straps, then pulled the pieces of wood out one at a time until I could get at the lines to disconnect them, then slid the tank out from under the bed. As I recall, I replaced the rubber lines to the hard lines and left them dangling, then reattached the sending unit ends when I got the tank close to the final position. Likely, the rubber lines were longer than they should have been, but I don't recall that being the big problem. I think I tipped the tank up on an angle, with the rear end of the tank on the ground so I could reattach the lines.
Or, just convert you bed to a dump box and you can get at them with a flip of a switch.

[DBLSPRT68]

Originally Posted by C10Silverado79

I don't have the equipment or facilities to take the bed off. If I unbolt the front of the bed, it there enough 'give' to jack up the front of the bed a few inches to provide access rather than pulling the bed all the way off? Right now it looks like dropping the tank is my only option.

Will you have an extra person around? You can unbolt the bed, and both of you lift it up and slide it back onto the tires; then some blocks or something. Even if your by yourself, unbolt the bed (use the PB blaster on the bolts before hand). Tilt the bed up and put something under the front. I don't know what to do about makeing sure it dosen't slide back any though? Bumper would hold it? Anyway, pull the bed, don't pull the tank; it sucks!

[78 Chevyrado]

just unbolt the bed except leave the rear most ones in and lift just the front end up. I did mine when the bed was off of it. Might be my big hands, but it was physically impossible for me to to it with the bed on. maybe if you have somebody around with small hands and you could walk em through it.... I do that every now and then with my daughter.

[C10Silverado79]

78 Chevy, We were thinking along the same lines. I just got done with the job. When I got under the truck I decided to try the bed bolts first. They came off with no problems to I decided to do just what you were suggesting. I removed the nuts on the front and just loosened the rear. Naturally, something has to be a problem so when I jacked up the front of the bed, the aftermarket fuel tank on the drivers side turned into a pain. The tank is mounted to the bed but is angled so that it's larger at the bottom. When the bed went up the tank went with it and hit the frame. I barely got the bed high enough to block it with a 4x4.

Getting to the sender and under the cab with only 4" of clearance was a pain with my big hands. I'm not sure if that was easier than dropping the tank or not but it's done so I'm happy. I disconnected the valve and extra fuel tank so they are out of the loop now. I'm hoping this solves my fuel delivery problems. If not, I'm not sure what the problem is.

Thanks to all for the help and suggestions.

[Mr79C10]

Originally Posted by silvereagle07

You will have to drop the tank. They sit under the cab more than the bed.

GOOD GOSH! and if you have never done this before. If you can REMOVE the bed. I swapped out my tank the other month. It will whip your arse doing it solo and on jack stands.

Also too,, swap out your sending unit.