Here's one for the savvy....

6

6cuda61

New member
Apr 17, 2020
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So i was under the coach yesterday just poking around and looking at what i can do to shore up the black tank strap with the broken mounting bolt and
something caught my eye......the fuel vent line "T" by the tanks....it was a brass "T" with good clamps etc....no way they had zipties or stainless
clamps in the 70"s.....hmmmmmmm :roll:

So i got a quick look and it appears that someone has been there before but and here's the but....when we picked up the coach last year and i filled
it to capacity for my first time i had fuel running off the top of both tanks...now the RV was parked slightly on a slope so it was running off the
left corners of both tanks so i know its not the tanks seams. So to prevent that the rest of the trip home i just didnt fill it to max capacity.

So here's the question.....if they did at one point drop the tanks and they did replace the lines within the last 10 years or so...what could have
been leaking? Fuel sending unit gaskets? Could the vent lines be bad again? Would their be a particular marking on the "new type" fuel lines that i
could compare to whats there? Is there other fittings that both tanks have that are not used?

I suspect i'm going to have to drop the tanks either way but i just want to be somewhat prepared.......out of every job in a garage you could pick
dropping fuel tanks is the one i hate the most! :(
--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
Rich,

I feel particularly qualified to answer this, not just because I had my tanks down five times, but that is part of it.

The fuel sending unit gaskets seem to seldom be the issue. But, when you get the tanks down they are easy to update.

No matter when the fuel lines were replaced, if the line material was not alcohol resistant, then there you go. I also made this mistake with an
early repair. I used rubber fuel line that I had kept in stock for a decade. Not only was it old already, but it only took about three years to go
bad again.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
my experience on 2 coaches I have done myself, and helped with 4 others. is the 1st thing to leak is the ventline. that comes off at a little bit
of a angle, so that connection tends to 1. crack 1st if old. and #2 might leak if it is a new hose and a hose clamp is not tightened enough. (new
hoses will shrink just slighty, so you want to use really good clamps and tighten them well).

the chance of someone replacing part of the gas lines is very high. I have seen that a number of times, where they splice into hoses that they can
reach and replace what they can short of removing the tanks, saving the problem of the hoses above the tanks for someone down the road later.

Like Matt said- the only times i Have seen senders leaking is when someone is not careful installing them. There is a lock ring, and the wrong
mechanic pounding on that with a screw driver can mess that up. there is actually a tool for installing those lock rings, that allows even twist on
it. but a careful mechanic can install them without the tool. I have seen 2 that someone looked like they installed it with a air chisel.

I am going to knock on wood- my coach that sat for 10 years and had all sorts of fuel line rotted off. and my friend Ed's coach, that also sat for
10 years. both have functioning fuel senders/pickups, and only needed new hoses. others have got into the project and found holes in the tanks, and
bad senders, or worrse.

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
Rich,

the tank job is really not that terrible of a project, and really is nice once it is done. You know what you have after that.

the biggest thing is to get it at the right height, and jack it up. The other thing is getting the fuel out. I found using an electric pump drains
99% of the fuel out, if you just hook it up and suck the fuel out of the pickups. it takes at least 15 gallons of gas to pour back in, before it
will start priming and sucking gas again. last couple tanks we emptied that way, there was hardly any gas in the tank to slosh out and dump on
you when you go to pull the tanks down.

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
Rich,
Being a bit of a fumble-finger myself, I'd make darn sure I had new sending unit O-rings on hand when dropping the tanks. I screwed mine up the first
time around and had exactly your symptoms. That said, as everyone pointed out, there are lots of potential leak points in there, including the
sending unit electrical terminal itself.

While in there the last time, I noticed that one of my pickup tubes sat about 2 inches off the bottom of the tank. (No way it should take 15 gallons
to start picking up fuel, IMHO.) So I carefully bent it down a bit.

BTW, if you can get the drain plugs loose, coat them with anti-sieze or some such to make sure they come out next time.

HTH
Rick Staples
--
Rick Staples, '75 Eleganza, Johnstown, CO

"Advice is a dangerous gift, even from the Wise to the Wise, and all paths may run ill." -Tolkien
 
Replace the plugs with the external square head instead of the internal hex.

On Tue, Apr 28, 2020 at 4:49 PM Richard H Staples via Gmclist <

> Rich,
> Being a bit of a fumble-finger myself, I'd make darn sure I had new
> sending unit O-rings on hand when dropping the tanks. I screwed mine up
> the first
> time around and had exactly your symptoms. That said, as everyone pointed
> out, there are lots of potential leak points in there, including the
> sending unit electrical terminal itself.
>
> While in there the last time, I noticed that one of my pickup tubes sat
> about 2 inches off the bottom of the tank. (No way it should take 15
> gallons
> to start picking up fuel, IMHO.) So I carefully bent it down a bit.
>
> BTW, if you can get the drain plugs loose, coat them with anti-sieze or
> some such to make sure they come out next time.
>
> HTH
> Rick Staples
> --
> Rick Staples, '75 Eleganza, Johnstown, CO
>
> "Advice is a dangerous gift, even from the Wise to the Wise, and all paths
> may run ill." -Tolkien
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
 
Thanks for the info guys.....i did get 2 sending unit lock rings and seals the last time is was out to visit JimK country. I have replaced many a GM
fuel sending unit and yes that tool is awesome but careful use of a hammer and blunt screwdriver can get it done.

Here's hoping its simple.....lol. Now to make a list parts for this job as this virus stuff is cramping my ability to just simple get what i need
easily.
--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
Rich,
Here are some pic from when I last had my tanks down. Mine was leaking from the vapour port as was previously mentioned. The nipple seams to be
installed using a crimp method like a pop rivet and becomes loose and leaks. I replaced mine and sealed it with JB weld. About 5 years now and still
good.

http://www.gmcmhphotos.com/photos/g7006-fuel-tank-lines.html

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
Thanks Bruce...guess ill have to drop the tanks and deal with what is there....lol.
--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
Most of my adult life, I have had a struggle with myself over starting a
procedure that I was unfamiliar with. Procrastination is the name of the
game. Not every time, but mostly my fears have been unfounded. Once I got
involved with the actual work, it usually went off well without all my
reservations coming up and biting me in the butt. Just Do It! is my new
mantra.
Jim Hupy
Salem, Oregon

On Tue, Apr 28, 2020, 6:46 PM 6cuda6--- via Gmclist
wrote:

> Thanks Bruce...guess ill have to drop the tanks and deal with what is
> there....lol.
> --
> Rich Mondor,
>
> Brockville, ON
>
> 77 Hughes 2600
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Also pay particular attention to the electrical connection for the fuel
level sender -- the insulating feed-thru can deteriorate and create a
leak. I don't have a good fix for that -- I tried replacing the insulator
with a nylon one, which only lasted a year or two. I finally modified some
SS assemblies from eBay -- but didn't get very good level accuracy from
those.

Ken H.

On Tue, Apr 28, 2020 at 9:30 PM Bruce Hislop via Gmclist <

> Rich,
> Here are some pic from when I last had my tanks down. Mine was leaking
> from the vapour port as was previously mentioned. The nipple seams to be
> installed using a crimp method like a pop rivet and becomes loose and
> leaks. I replaced mine and sealed it with JB weld. About 5 years now and
> still
> good.
>
> http://www.gmcmhphotos.com/photos/g7006-fuel-tank-lines.html
>
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> My Staff says I never listen to them, or something like that
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I trade on Matt and Ken's experience. Take the dam' things down once, and do ALL of it. ew seals, good electrical connections, proper barrier hoses,
use the genset feed if it was a trandmode with a tee, etc. If I had to take rust off the exterior, a couple rattle cans of Zinc - it.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
 
Agreed Johnny...hence all the questions as they are only going out once if i can help it.

> I trade on Matt and Ken's experience. Take the dam' things down once, and do ALL of it. ew seals, good electrical connections, proper barrier
> hoses, use the genset feed if it was a trandmode with a tee, etc. If I had to take rust off the exterior, a couple rattle cans of Zinc - it.
>
> --johnny

--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
Check the hose barb for the vent on the tanks carefully. The one on my rear tank was loose in the tank due to rubbing on the floor. I could not
believe their was no top retention for these tanks except the floor! So I sealed the loose crimp connection with superglue, and then reinforced it
with JB weld type stuff, and then glued pads on top of the tanks to stop the fittings (hose barbs) from abrading against the floor. Could not come up
with quick and easy way to retain the tanks from the top down so I just improved GM's idea a little with the plastic pads from some CD-ROM packing. No
evidence of there ever being any pads up there.
After fixing that and replacing the distorted and broken Corvette vapor separator valve in the wheelwell, no more leaks!
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.
 
Thanks for the tip Terry! Ill get a look at that for sure.

> Check the hose barb for the vent on the tanks carefully. The one on my rear tank was loose in the tank due to rubbing on the floor. I could not
> believe their was no top retention for these tanks except the floor! So I sealed the loose crimp connection with superglue, and then reinforced it
> with JB weld type stuff, and then glued pads on top of the tanks to stop the fittings (hose barbs) from abrading against the floor. Could not come
> up with quick and easy way to retain the tanks from the top down so I just improved GM's idea a little with the plastic pads from some CD-ROM
> packing. No evidence of there ever being any pads up there.
> After fixing that and replacing the distorted and broken Corvette vapor separator valve in the wheelwell, no more leaks!

--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
if you are having clearance issues to the floor, I would suspect your body pads are not in good shape. the tanks bolt to the frame, and there
should be some space between the tank and the floor. tank should float with the frame and not be attached to the floor. Opposite on a black sewer
tank, that rides with the body and is bolted to the floor, not the frame.

but Like I said, those vent nipples would be the first place I would look for a leak, both the hose, or the nipple into the tank.

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
If i went with solid supply lines on the tank and solid vent lines on the tank.....does anyone remember how lone they needed for the remainder of the
rubber line?

I'm just trying to buy the correct length of lines...Gates Barracade is not cheap so if i don't need 25ft and only 15ft that's a hug difference $$$
wise.

--
Rich Mondor,

Brockville, ON

77 Hughes 2600
 
I know everything in canada is more expensive it seems. - but I would think anything is comparable.

I did not think it was too expensive, you want the carburation hose: GAtes #27315 for the 3/8" and gates #27314 for the 5/16

now if you are going with EFI, then that is a different story. the EFI hose is expensive. for my EFI, I have the pumps just forward of the tanks,
so I am using the low pressure hose from the tanks to the pumps, then I switched to hardline to the engine bay, where i switched back to expensive
EFI hose.

the proper brass comression fittings to work and deal with the hardline, and the cost of the hardline itself, I would think would be more money then
the low pressure fuel hose.
--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
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