Maiden Voyage and fuel line fail

A

adam metzger

New member
Oct 12, 2016
162
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Hello everyone! We took the Mighty Drednaught (working title) on her maiden voyage. The plan was a two hour trip to a state park, to camp for. A
week. We brought two cars just in case something went wrong, and so we could day trip.

I had the Onan fired up to the ac pm and the fridge running. We filled up, and noticed that the fuel pump kept overfilling, and purging gas down the
side of the coach. I finessed more gas in, as it looked like we were getting about 27 gallons. How big are these tanks?

My father in law warmed up that the gas gauge was finicky, and indeed it was. Stayed up at full for a while, started dropping to 3/4, went up a bit
again. Once it got past 3/4, it started dropping fast. We pulled into a station, and sure as sunrise there was a fuel leak.

It was coming from a hose near the filters. The hose was cut, and at one time had a hose clamp on it. I stopped filling the tank and the leak stppped.

I poked around and found another hose that looked like it could be this ones mate. But it had a bolt stopping the end, fixed with a hose clamp.

Thinking that this one should look the same, I ran into loves, grabbed some clamps and a box of bolts, and proceeded to mimic the other.
Fuel dtarted coming out of the hose again, so at this point I'm up to my shoulder in cold gasoline. I get the clamp tight, and away we go. We stop
about 20 miles down the road, agter I notice the gauge going up... and fuel is POURING from the bottom of the coach.

Thinking I had perhaps plugged a drain hose? I unscrewed the bolt, my wife insisted that we load all non driver humans and animals into her car, and
we called the trip about 40 miles from our destination.

Made it home safely, with the drip continuing until about 5 minutes after we arrived.

Did I overfill the tank, block a drain, causing fuel to vent out of the top!?

Help troubleshooting encouraged.

--
1976 Palm Beach
Austin, TX
 
Sounds like you have an electric fuel pump added on there somewhere and it has been bypassed and the line plugged with that bolt...or maybe the
opposite of that...or maybe the two lines were connected with a pump that has been removed and only one side was plugged with a bolt, but that doesn't
explain why you still had a leak after plugging the other end. It is possible,(very easy, in fact) to overfill these coaches by putting the fuel in
slowly and then it can get into the vapor collection system (carbon canister) which on mine is behind the RF wheel. Then fuel and powerful vapors can
come out of the filter incorporated in that canister. Give us some more info on where the fuel was dripping/pouring out (left,right,forward,back,
etc.) and the smart guys on here will do their best to help you before you take the coach apart or pull your hair out.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.
 
Mine has 2 25 gallon tanks, but the most I have ever put in was close to 40 gallons and that overfilled it so it leaked out a crusty vent hose in
front of the left rear wheels. Lots of clamps and connections on these, check them all. If you have to fill it up with a can to make it leak again in
your driveway (to find the leak), be sure the furnace is OFF and the fridge is on AC power or turned off. Use a flashlight or fluorescent trouble
light, DO NOT use one of those burn-your-ass droplights with the incandescent bulb to find a fuel leak. Have seen several fires caused by those lights
when they crashed and broke the bulb on spilled fuel.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.
 
I am confused as to exactly which fuel line you are working on. There are fuel and vent lines all over that coach. Before you start trying to fix
this leak, you need to understand which lines go where and what they do.

As an example there are vent lines running to the gas fill, there are vent lines running to a fuel separator located in the left rear wheel well. The
is a line running from the fuel separator going on to the canister located behind the right front wheel. Then there are the normal fill lines and
lines running from each tank to the fuel tank selector and on to the fuel pump. There is another line between the fuel pump and the barb. Finally
there is a line en running to the ONAN. This is on a stock coach WITHOUT any PO modifications which is sounds like you might have.

Whatever you do get at least two working fire extinguishers and stand them on the ground next to where you are working. If you have a fire you will
not have time to go look for one. I know, I started mine on fire with a gasoline leak. It took 4 fire extinguishers and a garden hose to put it out.
After that, I had just under $10,000 in repairs to return it back to normal. .

For a gasoline fire, if you have a choice, get a foam type fire extinguisher. The next best is CO2. After that comes dry chemical and finally water.
Do not even bother with Halon or a halon substitute.

I went through all of the above (except halon) before I got my fire out.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Adam,

The most understandable fuel system diagram is here:
http://www.gmcmhphotos.com/photos/fuel-system/p51345-gmc-fuel-tank-diagram.html

It is easy to understand that your system has problems. All the rubber is junk and everything else is suspect.
It can all be fixed, but it will take some effort. It is, however, very much worth the effort.
(Says the guy that had his tanks down five times to finally get a funtional fuel system that yet again has a bad vapor valve.)

I will also direct you to read two threads that I started about this subject.
First is: Lifting fuel tanks when alone [message #174745] Wed, 27 June 2012 10:06
Second is: recommending high T [message #178309] Sun, 29 July 2012 21:06

Let me say again that it is worth the effort. The effort is also much less if have the coach high enough (you don't need a lift or a pit) and you
strap the tanks up and down so there is no juggling.

Matt
--
Matt & Mary Colie - Members GMCMI, GMCGL, GMCES
'73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
Now with both true Keyless and remote entry
SE Michigan - Twixt A2 and Detroit
 
Adam
I'm headed to Austin to relocate my GMC coach back to Atlanta.
I'm available to meet at your coach afternoon or evenings Monday Wednesday or Thursday week of 10/17.
My number
Four zero four eight six seven 3430.

George "I get by with a little help from my friends" Zhookoff
78 EL II
TAD Austin

>
> Adam,
>
> The most understandable fuel system diagram is here:
> http://www.gmcmhphotos.com/photos/fuel-system/p51345-gmc-fuel-tank-diagram.html
>
> It is easy to understand that your system has problems. All the rubber is junk and everything else is suspect.
> It can all be fixed, but it will take some effort. It is, however, very much worth the effort.
> (Says the guy that had his tanks down five times to finally get a funtional fuel system that yet again has a bad vapor valve.)
>
> I will also direct you to read two threads that I started about this subject.
> First is: Lifting fuel tanks when alone [message #174745] Wed, 27 June 2012 10:06
> Second is: recommending high T [message #178309] Sun, 29 July 2012 21:06
>
> Let me say again that it is worth the effort. The effort is also much less if have the coach high enough (you don't need a lift or a pit) and you
> strap the tanks up and down so there is no juggling.
>
> Matt
> --
> Matt & Mary Colie - Members GMCMI, GMCGL, GMCES
> '73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
> Now with both true Keyless and remote entry
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
At the worst of it, the fuel looked to be coming out of the front of the rear tank. I'll crawl under and trace the hose that was leaking to its
source.

George, my kids were in tears last night after having to come home. We may pack up the cars and go camping anyway, so I'll let you know if we don't
leave today.

Thank you so much for the generous offer.

Now, anyone know why the Onan would just quit?

A Keyed ingnition was installed to bypass the electric start. It kicks hard when you start it, but won't crank.
--
1976 Palm Beach
Austin, TX
 
When you say it "kicks hard" "but won't crank" do you mean it turns over
readily but does not fire?

Sully
77 eleganza 2
Seattle

> At the worst of it, the fuel looked to be coming out of the front of the
> rear tank. I'll crawl under and trace the hose that was leaking to its
> source.
>
> George, my kids were in tears last night after having to come home. We
> may pack up the cars and go camping anyway, so I'll let you know if we don't
> leave today.
>
> Thank you so much for the generous offer.
>
> Now, anyone know why the Onan would just quit?
>
> A Keyed ingnition was installed to bypass the electric start. It kicks
> hard when you start it, but won't crank.
> --
> 1976 Palm Beach
> Austin, TX
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Have your fuel and vent lines been replaced?? If not and they are still
the original lines, then they will leak fuel. This means you have to drop
your fuel tanks and replace all the fuel and vent (vapor) lines. This is
what I had to do to my two coaches (I actually did it to 4 coaches, two
that belonged to friends). I used metal lines on top of the tanks so I
would not have to drop the tanks again.
JWID.
JR Wheeler 78 Royale/73 PD NC/OR

> You need to make sure the onan is topped full of oil, and you have over
> 1/2 tank of gas. then diagnose after that is checked.
>
>
> --
> Jon Roche
> 75 palm beach
> St. Cloud, MN
> http://lqqkatjon.blogspot.com/
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
> ...Now, anyone know why the Onan would just quit?...
The Onan pickup is far enough from the bottom of the rear tank that there has to be more than 6 - 7 gallons in the tank for it to run.

Don't crawl under the GMC without blocking it up. If a bag blows or a torsion bar turns loose without it being blocked up, your family will be
collecting life insurance.
--
73 23' Sequoia 4 Sale
73 23' CanyonLands Parts Unit 4 Sale
Upper Alabama
"Highest price does not guarantee highest quality."
 
I meant that there is a single solid click when I turn the key. But no worries now, cause it's working fine.
--
1976 Palm Beach
Austin, TX
 
If I over filled the tanks, would it be possible for fuel to Come out of the top of the tank?

Would it be possible to get fuel in the filler vent line?

Fuel issues are no joke so we're grounded until I at least understand why it was happening.
--
1976 Palm Beach
Austin, TX
 
lots of possibilities for leaks. I have not seen any gmc motorhomes lately whose fuel lines actually look in great shape after any kind of storage
time. You will have to drop the tanks down and install new fuel lines to get rid of all leaks now and in the future. It is really not that tough
or super expensive of a task, if your tanks themselves are not destroyed by rust on the inside, and the senders are OK.\

start here:

http://www.gmcmhphotos.com/photos/fuel-system/p51345-gmc-fuel-tank-diagram.html

and here to see what they should look like:

http://www.gmcmhphotos.com/photos/mechanical/p34271-gas-tank-clean-up-2ffuel-line-replacement.html

--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
> If I over filled the tanks, would it be possible for fuel to Come out of the top of the tank?
> Yes, it could be a leaking hose or the fuel gauge.
>
> Would it be possible to get fuel in the filler vent line?
> Yes, The vent lines are on top of the tanks and go to just below the fuel fill cap. Theoretically, you could force enough gas in to fill the
> tanks, the vapor canisters, and everything else up to the the top of the fill next to the driver. As far as I can tell, filling these things is kind
> of a "seat of the pants" experience. Each time is different and depends on the pump nozzle, pressure, and how you hold your mouth.
>
> Fuel issues are no joke so we're grounded until I at least understand why it was happening.

I fill slowly, and refill every 200 miles or so. Others with more experience than me will check in shortly with tips and tricks.

--
Patti & Jerry Burt
73 Gmc 26' Canyon Lands -
Photos - http://jburt.smugmug.com/GMC-Motorhome
Lots of upgrades but lots to do to make it ours.
Members: FMCA - GMCMI - GMCWS - Pacific Cruisers
 
> lots of possibilities for leaks. I have not seen any gmc motorhomes lately whose fuel lines actually look in great shape after any kind of
> storage time. You will have to drop the tanks down and install new fuel lines to get rid of all leaks now and in the future. It is really not
> that tough or super expensive of a task, if your tanks themselves are not destroyed by rust on the inside, and the senders are OK.\
>
>
> start here:
>
> http://www.gmcmhphotos.com/photos/fuel-system/p51345-gmc-fuel-tank-diagram.html
>
> and here to see what they should look like:
>
> http://www.gmcmhphotos.com/photos/mechanical/p34271-gas-tank-clean-up-2ffuel-line-replacement.html

This is great info Jon. Man, you guys are awesome.

When
--
1976 Palm Beach
Austin, TX
 
By this point in time ALL coaches should be retrofitted with barrier fuel line if they have not been The old stuff is non ethanol compatible and
fails after a short time cracking and weeping fuel. A tremendous fire hazard. .
--
John Lebetski
Woodstock, IL
77 Eleganza II
Source America First
 
I help a friend who's Onan would not start. Found that the end of the fuel
hose connected under the Onan had split and broke off at the 90 degree
fitting. Fortunately we were in front of a NAPA store and replaced the
hose. Onan fired right up.
The old hose looked like some type of surgical hose as it was soft and
somewhat clear.

On Mon, Oct 17, 2016 at 7:18 PM, John R. Lebetski
wrote:

> By this point in time ALL coaches should be retrofitted with barrier fuel
> line if they have not been The old stuff is non ethanol compatible and
> fails after a short time cracking and weeping fuel. A tremendous fire
> hazard. .
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
> Source America First
>
> _______________________________________________
> 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
 
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