Fuel line replacement and tank venting

LQQKatJon

LQQKatJon

Well-known member
Oct 22, 2010
3,233
558
113
St. Cloud, Mn
lqqkatjon.blogspot.com
Weather is looking promising, it looks like saturday will be under a gmc replacing fuel lines.

Been doing some searching and looking over the photo archives to refresh my mind on how I want to go anout the project.

So what is the consensus(I know there might not be one). As to what you have done as for trying to improve things, mainly as it applies to the
venting?

I am looking at running both tank vents up as close and high as possible to filler tie in before t'ing them together.

Thanks
--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
> So what is the consensus(I know there might not be one). As to what you have done as for trying to improve things, mainly as it applies to the
> venting?
>
> I am looking at running both tank vents up as close and high as possible to filler tie in before t'ing them together.
>
> Thanks

Jon,

Running two vent hoses seemed to work well for those who have done it. I did my fuel hoses before that method was suggested and I don't have much of
an issue filling up until it starts to get near the top. The foaming of this ethanol laced gas is what causes the problem. Maybe running two
separate lines to the vent position on the filler neck would help with this. It sure can't hurt.

Just make sure there are no 'bellies' in the vent system that will hold liquid gasoline.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging
 
Jon,

You have the right idea, but mine is good and I didn't go that far.

Start by reading these two - put this in the search bar:
recommending high T, 29 July 2012 21:06
lifting fuel tanks when alone 27 June 2012 10:06

You may not be planning on taking the tanks down but think about doing it. That is the only way to get the job done right is to get to the sending
unit is to let the tank down. If you do that with the straps, it is just not all that tough. It is easier will less fuel. But, if you can't get the
drain plugs out and you can get a small pump to use the existing fuel lines to pump the gas into something.

Another thing to think about is that the fill pipe is completely in your way and it is easily removed. So, after the first couple of times I had to
do this I took up doing it that way. It was much easier and simpler.

If you are working on a hard floor, this is much easier than a floor jack because the jack has to be where you need to be.

Good Luck

Matt

--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Still Loving OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
First couple of times??? What happened to "once and done". Man, I hate
doing a job over because I DIDN'T DO IT RIGHT THE FIRST TIME. This is not a
criticism of your work. Just an observation of my frustration over MY OWN
careless work when I do not do it right the first time.
Jim Hupy

> Jon,
>
> You have the right idea, but mine is good and I didn't go that far.
>
> Start by reading these two - put this in the search bar:
> recommending high T, 29 July 2012 21:06
> lifting fuel tanks when alone 27 June 2012 10:06
>
> You may not be planning on taking the tanks down but think about doing
> it. That is the only way to get the job done right is to get to the sending
> unit is to let the tank down. If you do that with the straps, it is just
> not all that tough. It is easier will less fuel. But, if you can't get the
> drain plugs out and you can get a small pump to use the existing fuel
> lines to pump the gas into something.
>
> Another thing to think about is that the fill pipe is completely in your
> way and it is easily removed. So, after the first couple of times I had to
> do this I took up doing it that way. It was much easier and simpler.
>
> If you are working on a hard floor, this is much easier than a floor jack
> because the jack has to be where you need to be.
>
> Good Luck
>
> Matt
>
>
>
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Still Loving OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
> First couple of times??? What happened to "once and done". Man, I hate doing a job over because I DIDN'T DO IT RIGHT THE FIRST TIME. This is not a
> criticism of your work. Just an observation of my frustration over MY OWN careless work when I do not do it right the first time.
> Jim Hupy

James,

You and I share an aversion here, but just to clarify and maybe - Just Maybe - prevent another from following my wandering path, I put the situation
down for all to read and hopefully profit thereby....

Matt's Fuel tank stories. (Cliff notes version)

First tank drop:
Shortly after we got the Chaumière in 2006, I noticed fuel leakage after filling. It wasn't until the next spring that I identified it as a rubber
line that was up against the frame rail. I got to know that this as the fill vent line. It was shot, brittle and crumbling. I thought the easy way
to get at it would be to take the tanks down. I didn't know that I could have done the most ot the job by just taking down the fill pipe. That was
the first time and I did it with lots of fuel still in the tanks and a floor jack. I did notice that the existing fuel lines had been replaced.

Second tank drop:
I had begun to notice a bad reading from the main tank sending unit. The coach was now regularly employed as a mobile office, workshop and tool crib
for the boat work, but we were planning a RT-66 run to Albuquerque for the Balloon Fiesta and I wanted it working. I had run the fuel low and in the
prior adventure had gotten the drain plugs to loosen, so I drained the tanks and just dropped them. I repaired the bad connections in the senders (I
believed) and when I went to put the tanks back up, I though long and hard about the problems the last time. I went to Hazard Fright and bought the
on sale set of cargo straps and used them to sling the tanks back up. That was easier, but it was still a bear getting the fill connections made.
The connection to the auxiliary tank went bad. So, rather that take the tank down again, I attempted to straighten things out by dealing with the
fill pipe. It came out and went back in with great ease. Now that fill pipe is always a first part of the process.

Third tank drop:
Now both fuel senders were bad. I was sure that my prior repair was inadequate, but I had lots of fuel onboard, so this time I pumped the tanks out
into a clean plastic drum, took the fill pipe down, and dropped both tanks on the floor alone in an afternoon inside my barn where I can only lift the
coach about 14" above right height. I did a better repair to both senders by solding a wire directly between the element and the terminal. The
senders tested well. The tanks were back in place and full by the next afternoon.

Forth tank drop:
Fuel leakage reared its head again and I drove up on a curb in Fancy Gap Virginia to assess the leakage only to find that the fuel lines replaced
before the coach came to Michigan were leaking and wet along a lot of their length. This is not the place to make such a repair. When we were
safely back in the barn the tanks came down again. This time I read a lot more on the forum and copied Emery's plan for the larger part. All the
lines that were not easily accessed with the coach on the ground and the tanks in place were replaced with Polyarmor. There is now only about five
feet of rubber hose remaining. That is now all Gates Barrier hose.
**This was after I had done the CFD on the fuel system and discovered the fill vent problem. So that was changed by moving the T to just under the
cab floor. That fixed that issue.

Fifth and LAST Tank Drop:
Fuel gauges went weird again. (I still think it is SBS (a special kind of stupid) to have the reading go to full on an open circuit.) Tanks came
down again and senders came out. They were out for a while this time. Now the wipers were bad on the nichome windings of the sender. I tried to
clean things but I could not seem to make them reliable. I investigated getting them repaired and heard of a shop in California that could do it.
(Remember they are no longer a stock sender because of the metal line attachment.) I never located that shop. I did locate replacement GM spec
sending units. How hard could this be? I ordered a pair. The manufacturer assured me that they were completely ethanol proof. When I got looking
at them, I determined that they were backwards from the OE and the float would cost a quarter of the tank's depth. So, I disassembled them, and
mounted them to the exiting mount and spliced the float arm to the original float. This was all a monumental PITA and the reason you have not read
about this mod on GMC net is simply that it is not nearly a good ROI unless you already bought the wrong parts and want to get the coach back
together.

When I was through putting the tanks back up I took the coach out for a run and ran the main tank dry. OK switch tanks. Gauge says fuel but the
engine says NOPE!. I nursed her back to the barn. The auxiliary tank did have fuel, the main did not. So, I took down the tank selector valve.
There was nothing I could do on the bench to make it select the auxiliary feed. It got replaced with a Standard part that is only upside down and
backwards from the OE, but it works.
This last bit was in 2011 and about 40k miles ago. We now count on the fuel gauges and the system working as it should. The last fuel leakage issue
was the double carbon canister for California that is gone. There was a kink in the hose between the two. That kink prevented its purging clearly
enough and it would drip fuel days later.

You may have noticed that apart from good hindsight, each of these services could easily have been the last for this topic. If you bother to learn
from my experience, it may be so in your case.

Now you know why I am such an expert on fuel tank service.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Still Loving OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
This will be my second tank drop. But is is not on the same coach, and like the first tank drop, i am sure it will be by myself. Coach is up on
ramps on my concrete driveway.

I will curse myself later I am sure, and be one of i should of done it right the first time guys. but not planning on replacing the senders as the
coach is a good strong runner, just with some leaks on gill up and hoses you can see are crusty looking.

I did not think dropping tanks was all that difficult, but that was 6 years ago. More a hassle of jacking up the coach, and getting the tanks
empty, Then actually dropping the tanks themselves.

My coach could do a little better on the fill ups, and i kept fuel line routing oem on that. So i figured if there was something i can do to improve
and try to illiminate the burp overflow, that happens on mine when filling up and not paying attention. I would do that.

--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
> This will be my second tank drop. But is is not on the same coach, and like the first tank drop, i am sure it will be by myself. Coach is up
> on ramps on my concrete driveway.
>
> I will curse myself later I am sure, and be one of i should of done it right the first time guys. but not planning on replacing the senders as
> the coach is a good strong runner, just with some leaks on gill up and hoses you can see are crusty looking.
>
> I did not think dropping tanks was all that difficult, but that was 6 years ago. More a hassle of jacking up the coach, and getting the tanks
> empty, Then actually dropping the tanks themselves.
>
> My coach could do a little better on the fill ups, and i kept fuel line routing oem on that. So i figured if there was something i can do to
> improve and try to eliminate the burp overflow, that happens on mine when filling up and not paying attention. I would do that.

Jon,

When I dropped my tanks and replaced all the fuel lines in 2010, I did not even take the senders out. They worked and didn't leak, so I just left
well enough alone. So far, seven years later, they still work and still do not leak, so I guess I made the right decision at the time. I guess it
could have gone both ways and I have second guessed myself on that several times. Just what I did.

I did replace the hoses on top of the tank with Polyarmor lines, but coupled them to the outlets with some of the rubber barrier hose that I bought
from Applied GMC. It has lasted longer that I might have expected it to, considering all the things I have heard abut rubber and ethanol.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging
 
I ran 2 large vent hoses, 3/8" all the way to the filler.

It's still possible to get it to burp if you let it foam up.

________________________________
From: Gmclist on behalf of Carl Stouffer
Sent: Tuesday, April 18, 2017 1:12:22 PM
To: gmclist
Subject: Re: [GMCnet] Fuel line replacement and tank venting

> So what is the consensus(I know there might not be one). As to what you have done as for trying to improve things, mainly as it applies to the
> venting?
>
> I am looking at running both tank vents up as close and high as possible to filler tie in before t'ing them together.
>
> Thanks

Jon,

Running two vent hoses seemed to work well for those who have done it. I did my fuel hoses before that method was suggested and I don't have much of
an issue filling up until it starts to get near the top. The foaming of this ethanol laced gas is what causes the problem. Maybe running two
separate lines to the vent position on the filler neck would help with this. It sure can't hurt.

Just make sure there are no 'bellies' in the vent system that will hold liquid gasoline.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging

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