Fuel filler neck and hose

[rdnether]

Anyone have a good source for filler necks and hose for these trucks?  Mine is a 78 with side mount tanks, I believe the hose is 1 3/8" (35mm).
Thanks!

[bake74]

     First off welcome to the forum.
     When asking for parts, it is helpful to list all the details of your truck that will enable anyone here to help you out.  You listed it was a 78, but did not mention C or K series.  10-20-30 series, and what engine you have.
     So going off a 78 C-10, with a 350 engine, I looked up O'reilly's Auto Parts and came up with 5 filler hose choices and 3 filler neck choices.
     I am sure a internet search would result in more choices.

[rdnether]

Sorry about the missing details, it is a K25, with a 350, AT.
I've been to O'reilly's (both the store and the website).  The only thing they have is a straight 1 3/8" line, the original has a 45 deg bend, so I'm not sure how that will work out.
Thanks!

[ehjorten]

Many '73-87(91) online truck part retailers have these parts.  I just got some for my '77 K20 that should be the exact same ones you need from a large aftermarket place that we shall not name here.  They fit perfectly.  If you have dual tanks then the filler hose is the same for LH and RH tanks, but the vent hose is a different piece from LH to RH due to the location of the vent nipple on the tank swapping sides of the filler nipple.

[xschroederx]

I usually order parts for my k10 off ebay cause I can get a better price usually on new items. What carb do you have? Im stillrunning the 4barrel rochester (stock carb) usually the aluminum hose that goes to the carb from the mechanical fuel pump has the filter in carb right where the hose connects. Dont attempt to put in an in line filter as it will cut down on fuel flow and your truck will run like crap. The hose you can pick up for close to 25 at most auto parts stores or gm dealerships. The filter is about 5 bucks. Why are you replacing them?

[rdnether]

I am still running the original Rochester carb. Thanks for the heads up on the in-line filter, I had considered installing one while I am replacing lines.
I am replacing the hose because it is leaky and rotted.  It is not the original, whoever replaced it used 1 1/2" hose even though it is supposed to be 1 3/8". It is really a hack job, but they probably ran into the same problem I am having.  I want to replace the filler neck because the stamping at the top of the neck that the cap screws into is in bad shape.  The cap really does not fit well, don't think a new cap will help.
I have been searching all my usual online sources for an application specific filler hose and neck for a few days, I'm not having any luck.  The only place I have been able to find generic 1 3/8" (35mm) hose is at O'Reillys, and that is a straight section, original has a 45 deg bend.  I have looked on ebay for a used filler neck, no luck.
If I remember correctly, 78 is the first year with a fuel door, maybe that's why I'm having difficultly?
Any recommendations of online sources I could search?
Thanks for all the input!

[rdnether]

My truck...

[xschroederx]

My old 78 had the caps on the filler tube. My 79 has the door. You could customize it even and it would work if you did it right. Can you post a picture of what your talking about? Just so I can see the full problem?

[ehjorten]

to my understanding the '79 was the first year for the fuel door.

[rdnether]

The plot thickens!  I did find a source for the parts I need.  It shows the fuel door started in 79.  My truck is a 78 GMC. I wonder if the bed was changed out?  Any other way to verify that?
Thanks!

[xschroederx]

Its possible the bed was swapped. You can still customize what you need. Got a pic to post?

[ehjorten]

An early fuel door bed will need a filler hose for a '79 to what?...'81?  the fuel tanks prior to '82 had a 1-3/8" fuel fill.  After that they changed to a fuel fill diameter to like 1-3/4" or something?

My sizes and years might not be completely accurate, but there was a change.  I do know the earlier years had 1-3/8" fill.  You could change over the fill neck, tanks and part of the bed that the fill attaches to, to change it over to the larger fill if you so desired.  All of those pieces are available.

[rdnether]

This is a pic of the existing filler neck. It does use 1 3/8" hose. This really does not match the pictures I am seeing on  , but it does come closer to the pics for the newer trucks (part 32-3365).  Can anyone identify the year on this neck?

[ehjorten]

I say you get the hoses for '79-'81 and you will be good!  Shoot...even the 73-78 stuff will probably work.  The geometry can't be all that different.  The hose size is still 1-3/8" and the vent stuff really didn't change.  You still have a pre-formed 90° bend at one end for the tank and some longer length of hose on the other side of the 90.

I don't see where Chris has these parts available on his catalog.  Other sites seem to have a sporadic selection of one item or the other, but not everything that you need.  For this one particular issue it seems that other company does have the best selection...that I have found.

[jaredts]

If it were me I would try the junkyard for the filler neck.  I don't think you'll have a problem finding one.  For the hose I got mine from NAPA, but had also found a few places online.  You don't want to search online for your specific vehicle, but rather the bend angle and diameter that you need.  "90 degree 1-3/8" fuel hose" as a search for example.