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emptying a gas tank
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Supporting Member of Barthmobile.com 12/07
posted
My 2 40 gallon tanks are ful and I need to empty them so that I may drop them to check and probably replace the socks at the pickup... I have replaced the front mechanical fuel pump and the inline fuel pump for the number 1 tank but need but continue to get low gas pressure which tells me that maybe the pick up point in the tank is clogging...the pressure in the line starts out at 5/6 and decreases rapidly to 0 as I travl down the road and get the MH going ...If I ease off the gas I can get it back to 5/6 but any stress on engine brings it right down again..
So how do I empty those tanks..
One frustrated Barth owner
John Reilly
Centerville Ohio
 
Posts: 127 | Location: Centerville, Ohio, USA | Member Since: 09-18-2004Reply With QuoteReport This Post
The Old Man and No Barth
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You didn't mention fuel filters. There should be one in the carburetor inlet, and at least one, possibly two, in the fuel lines between the tanks and the engine-mounted fuel pump. They are the most common source of fuel flow problems. All I've seen on motorhomes, including my Barth, are off-the-shelf items.
 
Posts: 1612 | Location: Upper Left Corner | Member Since: 10-28-2002Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 12/07
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replaced the two in line I founf and the one in the carb... also tried to follow fuel line to look for a crimped line or mybe a nylon tye that was used to hold the fuel line in place that was too tight...
I start off with 5/6 pounds of pressure and as I start up it drops to 2/3 and if I try to accelerate too quickly I go to 0 and the motor coughs .... If I go up a hill I am babying it to keep fuel in the line as the pressure goes to 0 and I am losing speed and power as I accend..
I am running out of options but two things I find confusing..If it is the sock in the tank is it not funny that they are both clogged at the same time or because I use tank 2 mainly that 1 has been clogged for a while and I never knew it....
I am not a mechanic and all this is way over my head but to the ones I have taken it to... well I just don't feel comfortable..
so I am back to the drawing boards getting frustrated that I do not feel comfortable in my Barth... so it is just sitting and I am sleeping in the back of the suburban again at dog shows or in a motel... Not what I want to do..
Thanks for the reply and allowing me to vent..
John Reilly
Centerville Ohio
 
Posts: 127 | Location: Centerville, Ohio, USA | Member Since: 09-18-2004Reply With QuoteReport This Post
The Old Man and No Barth
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If you've replaced the filters & the fuel pump, and checked the fuel lines for kinks, etc., it sounds like the only things left are something in the tank, or in the condition of the fuel lines themselves. I've had two experiences, one with a boat, one with a motorhome, where the interior of the fuel line had swollen, or flaked off enough to restrict the flow.

Before you take it to the pros, you might check, & replace each section of the flexible lines. If the end of the line is cracked & swollen, the inside is probably bad, too. Also check the condition of the metal line betweeen the fuel pump & the carb. That's rarely a problem, but it might be kinked.

I'd start at the carburetor, & work back. Since you're drawing from both tanks at once, it's most likely the restriction is downstream from where the flow from the two tanks joins.

Another thing, I found the the in-line fuel filters come for 2 diameters of hose. Mine took the larger one, I suspect for good reason, and if you have the smaller filters, and/or your lines have been repaced with the smaller stuff, that's a possible problem too.

If your fuel lines & filters are all the right size, & in good condition, that leaves a restriction in the tanks. When everything else has failed, try slowly blowing some air into the tanks from the fuel line below - just enough to get bubbling - too much and you'll be blowing gasoline out of the tank, and that's a big no-no.

With 80 gallons of gas, all of this is fraught with danger, and the safety issue is complicated. You have to do your darndest to prevent a spill. I'd start by clamping off the first section of line downstream from where the flow from the tanks joins, and work all the lines downstream from that. If your lines are old & brittle, the clamped section might suffer enough damage to require replacement too.

I dropped the tanks on a GMC MH, & replaced what seemed like yards & yards of fuel line, but both tanks were nearly empty. On my previous SOB, with a half-full tank, I hired it done.

Bill h might have some greater words of wisdom for you. I know one thing, I wouldn't try to drop the tanks, unless they were empty, & 80 gallons of fuel is a lot of gas to store around home.
 
Posts: 1612 | Location: Upper Left Corner | Member Since: 10-28-2002Reply With QuoteReport This Post
First Month Member
Supporting Member of Barthmobile.com 11/13
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Have you tried Red Line fuel system cleaner? It can sometimes work wonders.

I wouldn't worry about dropping the tank yet. Do what Roy said and replace all flexible fuel line. It could be clogging like Roy said, or the pump could be sucking air through a crack. Old fuel line should be replaced anyway for safety.

If new line doesn't take care of the problem, use the electric pump to pump the gas directly into another vehicle(s) and containers.

I had a car that drove me crazy once. Turns out there was a floating gob of viscous slimy crud that wrapped itself around the sock whenever the fuel level got low or I climbed a hill with half a tank or less. Do you remember fueling up right after the tank truck filled the station's tanks? That always stirs up crud.
 
Posts: 7300 | Location: AZ Central Highlands | Member Since: 01-09-2001Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 12/07
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OK thank you Roy and Bill I guess I am off on another adventure or should I say frustration adventure.. Anyway I will start at the carb and look at replacing the fuel lines... I do feel somewhere in this adventure I will be unloading the gas tanks as if for no other reason to replave the fuel lines... I figure I'll be loading up my suburban 5 gallons at a time..
thanks for keeping me going and if you start wondering where I went I'll be under the Barth cussing up a storm
John Reilly
Centerville Ohio
 
Posts: 127 | Location: Centerville, Ohio, USA | Member Since: 09-18-2004Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 12/07
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I forgot to include I will keep you posted on my progress..
John Reilly
 
Posts: 127 | Location: Centerville, Ohio, USA | Member Since: 09-18-2004Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 8/13
Captain Doom
Picture of Rusty
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If you do have to empty and drop the tanks, a motorcycle/ATV jack from Pep Boys makes handling it a snap - I had to drop a tank on my 1-Ton van, and it was no problem.

Also, if you can get a fuel/vacuum gage with a tee fitting, inserting that into the fuel lines at various places might help you to isolate the location of the problem.

Finally, there's a possibility that the problem is not in the fuel lines but in the tank venting - check the vents/lines for problems.
 
Posts: 7036 | Location: Brooker, FL, USA | Member Since: 09-08-2005Reply With QuoteReport This Post
First Month Member
Supporting Member of Barthmobile.com 11/13
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quote:
Originally posted by JReilly:
I do feel somewhere in this adventure I will be unloading the gas tanks as if for no other reason to replace the fuel lines...


Assuming you can reach them, the fuel lines should be replacable without emptying or dropping the tanks.

However, it would be a good idea to soak the tank hardware daily with PB Blaster just in case.

In addition to Rusty's suggestion of a motorcycle/ATV jack, a transmission jack works well, too.

[This message has been edited by bill h (edited September 15, 2005).]
 
Posts: 7300 | Location: AZ Central Highlands | Member Since: 01-09-2001Reply With QuoteReport This Post
"First Year of Inception" Membership Club
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John and all you guys since you installed the engine driven pump would it be possible that maybe the return and pressure lines were installed wrong? When I installed mine I had a return relief line going back to the tank and one going to the carb and also the supply line. I'm not sure if its even possible but just a thought.



John check all the rubber connecting lines at the engine pump, make sure that the lines aren't in too tight a radus causing them to
suck shut when the pump is operating. Also can you hear the electric boost pump running?

Ralph
 
Posts: 172 | Location: LaFontaine, IN,USA | Member Since: 07-03-2001Reply With QuoteReport This Post
Picture of Relative
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Mine wasn't a Barth, but was on a motorhome P-Chassis. Had mechanical pump on the 454, inline electric near the rear axle and electric pump in the tank. Could be your tank pump(s) are kaput.

Also, there was a second in-line filter near the rear axle (actually there were two back there, the other one was for the gasoline generator line).

Sequence was: In-tank electric pump, tee to filter on frame rail (other side of tee to generator filter), electric pump on frame rail, pressure regulator on frame rail, in-line filter in engine compartment, mechanical pump, carb filter. No filters or other gobbledegook on the return line to the tank. That frame rail filter caused me a few problems until I discovered it was there. Also, that pressure regulator had its own return line to the tank - I assumed it was for the excess pressure and that's how it regulated. There was also a pressure regulator at the input to the carb.

This sounds like a TBI setup, but it really was on a carburetor model.

Mike

[This message has been edited by Relative (edited September 15, 2005).]

[This message has been edited by Relative (edited September 15, 2005).]
 
Posts: 143 | Location: Garden Grove, CA (soon) | Member Since: 06-09-2005Reply With QuoteReport This Post
"Host" of Barthmobile.com
Supporting Member of Barthmobile.com 9/13
Picture of Bill N.Y.
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Idea #1

Remove both gas caps, Hook up a low psi airline with a rubber blow gun tip and blow back down the fuel line from the rear most filter back to the tanks. This will blow the crap out of the sock and if that is your problem it will run better for the short term. Then after getting your tanks low enough drop them out and clean your tanks at a radiator shop. If that doesn't take care of the problem then check for a collapsed suction side line.

Idea #2

Hook up an electric fuel pump at the inlet to the mechanical one. Run the other end into a 5 gallon can. (do not hook up the mechanical at all) Pump the fuel out to see if you get a good volume of fuel. If you don't then it is a suction restriction or you're sucking air into the brittle lines.

Idea #3

Install an electric fuel pump at the pick up above the tank and run it. If it runs well then your hoses are sucking shut. If not then it may be the sock in the tank. Before driving away look to see if the fuel is leaking with the electric pump running. If the hoses are cracked it will leak so check before you start it up.

I know this sound like alot but this is how I would check it. Let us know what you found.
 
Posts: 7111 | Location: Newburgh, New York | Member Since: 05-10-2003Reply With QuoteReport This Post
First Month Member
Supporting Member of Barthmobile.com 11/13
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On the car that drove me crazy, I ended up running a vinyl tube from the electric inlet pump to the filler neck. Car ran fine then, so I knew the sock was clogged.
 
Posts: 7300 | Location: AZ Central Highlands | Member Since: 01-09-2001Reply With QuoteReport This Post
Picture of Relative
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Did a little more research and came up with the following:

For up to 1985 models, GM gave a field fix to all RV manufacturers for vapor lock and low pressure problems that installed another in-line filter, external electric fuel pump, a pressure regulator and a bypass line with check valve. The purpose of the bypass line was to allow the mechanical pump to suck gas directly in case the external electric pump and/or the regulator failed. It was up to the RV manufacturers to implement the fix.

Best external electric pump was AC P/N EP89. If this particular pump was used, the regulator wasn't necessary as it pumped at slightly less than 5PSI. Any other electric pump an RV manufacturer chose would probably require a regulator.

The bypass line was 3/8" and the bypass check valve was from Aluminum Fabricated Products (their P/N AFP 200). A Parker-Hannifin 3/8" female hose connector fitting (P/N 126HBL-6-6) is fitted to the valve to allow connection to the bypass line.

An in-line filter (P/N GF62C) was recommended for addition between the tank and the external fuel pump.

Here's the catch: - the external electric pump is only activated when the oil pressure switch picks a relay switch to supply power. If something goes wrong in this circuit, the electric pump doesn't kick in. This applies to ALL carbureted models with an electric fuel pump, internal or external. That relay switch and wiring from the oil pressure switch through the relay and on to the external electric fuel pump was a field fix and can be all sorts of configurations. If that bypass valve and line weren't added, or is gummed up by now, the mechanical pump will have a great deal of difficulty getting fuel.

Following are the GM part numbers for the items listed for factory production when this 'fix' started coming down the production line:

1985 1/2 thru 1989 production:

40-gallon tank in-tank pump P/N 6572311
40-gallon tank hi pressure hose to external regulator P/N 15530451-40

60-gallon tank in-tank pump P/N 6472526
60-gallon tank hi pressure hose to external regulator P/N 15530451-60

Fuel Filter is AC type GF-509.
External fuel pressure regulator P/N 15598336
Electrical relay switch GM P/N 15528707


1990 - 1995 with FUEL INJECTION:

In-tank fuel pump (all size tanks - 40, 60 or 80 gallon) P/N 6472763.
In-tank fuel filter P/N 25055455.
Fuel Filter is AC type GF-481, GM P/N 25055052.
Electrical relay switch GM P/N 10052954

Hope this helps,

Mike
 
Posts: 143 | Location: Garden Grove, CA (soon) | Member Since: 06-09-2005Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 12/07
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Mike Great info ..Where does one get that kind of info... Tomorrow is the big day as I am tackling the project..
I appreciate your efforts and passing the info along.. I have a feeeling the problem is in the tanks the result of bad gas and 19 years alot of which was done outside sitting...
This list continues to amaze me..
I hope the whole process takes little time and the end result is successful...
John Reilly
Centerville Ohio
 
Posts: 127 | Location: Centerville, Ohio, USA | Member Since: 09-18-2004Reply With QuoteReport This Post
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