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xflyer
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Joined: June 15, 2006
Posts: 314
Location: SOCAL
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 Posted: Mon Jul 01, 2024 3:53 pm Post subject: Re: 2 Wheel Drive Gas Tank Cut Open |
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"The FI'd Bay Window buses don't have screens in their tanks and don't seem to have problems until the tanks become very rusty inside"
I was repairing/servicing VW vans when the Bay window vans were new. It took a few years, but most of the vans here in California had trouble. When the cause was discovered we were wishing for the finger sized screen that was in the non EFI vans.
The Bay window vans with catalytic converters had a restrictor in the filler neck just inside of the fuel filler cap. It was molded into the rubber elbow that did a 90 degree turn from the side of the van to the pipe going to the tank.
It became known as the "beak" as from the inside of the elbow it looks like a bird beak. Chunks of rubber would break off after years of the gasoline nozzle being pushed in and pulled out. If the chunks were smaller than the fuel lines in the bottom of the tank they would go down to the filter and not cause trouble. If the pieces could not fit in the outlet they could get stuck there and restrict the fuel feed to the pump.
The engine would shut off when the engines requirement for fuel exceeded the trickle that could get around the blockage.
The fix was to add, if it was not already there, the Service Bulletin access hole for the fuel gauge sender. Then remove the sending unit and using a sharpened length of wire coat hanger or welding rod, spear the chunks of rubber and remove them.
Sometimes it was necessary to do this several times as bits of rubber could be off to the sides out of visual range.
Having a screen would allow the motor to stay running for some time until it got completely plugged with debris. Of course with a partially clogged screen if the tank got low fuel flow would stop. However due to the Bay window tank design the screen was easily removable for cleaning or replacement.
Same thing could happen to a Vanagon if there was no screen unless the tank was cleverly designed to allow fuel flow when large pieces of debris are in there. Have read reports of people finding one or more of the vent grommets in the tank.
Yes the screen(s) will clog eventually. Most vehicle manufacturers are mostly concerned with getting through the warranty time and maybe a little longer.
I'll take my two Vanagons over my partner's Mustang. Ford put all the fuel tank bits into a large cartridge that goes into a hole in the top of the tank. Fuel out to engine, return line, and fuel gauge sender are all there. Thing is pump lasted half, or less, than the life of a Bosch VW pump. PITA to get the tank out to access the pump.
And yes a screen type filter on the outside of the Vanagon tank would be better, but the Bean Counters will not allow it.
You could install one along with an aftermarket tank that has no screens.
https://www.summitracing.com/parts/sum-g1509
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1989 Campmobile, 1984 7 passenger beater Vanagon
Both with cool A/C |
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raoul mitgong
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Joined: July 05, 2009
Posts: 1340
Location: Denver, CO
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| Posted: Mon Jun 22, 2015 8:57 pm Post subject: |
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djkeev,
When you cut open your new gas tank, be sure to pry up that center square of sheet metal to see if there is anything hiding in there. Looked like something yellow in there though one of those holes.
-d
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84 Westy with a 2.1 (Groover)
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86 Tintop Syncro to Westy project (Tom Servo)
91 Westy (Only the top 12 inches of this van (a burn victim)) |
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Merian
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Joined: January 04, 2014
Posts: 5212
Location: Orygun
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| Posted: Mon Jun 22, 2015 3:56 pm Post subject: |
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you are very welcome to drop by - I will also buy you a beer
I'll be sure to keep a safe distance from your Vanagon... |
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djkeev
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Joined: September 30, 2007
Posts: 32989
Location: Reading Pennsylvania
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Merian
Samba Member
Joined: January 04, 2014
Posts: 5212
Location: Orygun
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| Posted: Mon Jun 22, 2015 2:02 pm Post subject: |
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| djkeev wrote: |
I feel as if I'm on trial for dissecting a fuel tank and reporting my findings.
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No you are on trial for not replacing the brake lines.
Thx for the tank pics. |
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B-bear604
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Joined: August 16, 2014
Posts: 118
Location: Delta BC
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| Posted: Mon Jun 22, 2015 8:04 am Post subject: |
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Hey Dave great post, I love seeing what is inside stuff and how things work.
I to find it strange that VW would put an unservicable filter in the tank like that. I know that my Benz has a similar screen but can be removed as it is part of the connection to the tank.
Thanks again for the post it may answer some fuel flow problems that some people may be having
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Brent H
1991 Westfalia Multivan "Vicki"
1986 Westfalia "Wolfsburg Edition" Lowered, RIP😭
2005 Jetta Wagon TDI
1985 Mercedes 380sl |
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Wildthings
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Joined: March 13, 2005
Posts: 52382
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| Posted: Mon Jun 22, 2015 7:54 am Post subject: |
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| A large flat bottomed tank is going to give problems, I don't see a way around that. |
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transanalog
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Joined: April 06, 2011
Posts: 67
Location: New Orleans, Louisiana
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| Posted: Mon Jun 22, 2015 7:41 am Post subject: |
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Very interesting seeing the inner workings of the bottom of the front seats. I agree, having a non-serviceable inner-tank filter is bad.
Not to somewhat hijack this thread, but looking at the internal working of these tanks, it seems like the right turn fuel starvation syndrome is unavoidable? The PO of my current van ('91 Carat) put in what I can assume is the cheapest aftermarket fuel tank he could find. I get right turn fuel starvation with as much as 4 or 5 gallons still left in the tank. My previous van ('90 Carat, RIP) would wait until about 2 gallons were left before RTFS. So, since we're on this topic, anyone have experience with aftermarket tanks that are more tolerant to right turns? If so which ones?
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Mike
New Orleans
1991 Vanagon Carat |
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Merian
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Joined: January 04, 2014
Posts: 5212
Location: Orygun
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| Posted: Sun Jun 21, 2015 6:41 pm Post subject: |
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| you need a mass spec. |
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djkeev
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Joined: September 30, 2007
Posts: 32989
Location: Reading Pennsylvania
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djkeev
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Joined: September 30, 2007
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70coupyel
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Joined: September 06, 2006
Posts: 1657
Location: So.Cal
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| Posted: Sun Jun 21, 2015 2:51 pm Post subject: |
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Man is it fun to take crap apart or what! Thanks. And you have fine taste in pump oil cans.   
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| TheAndante wrote: |
| Saying that specs are different than dimensions doesn't make sense. Porsche specs/VW specs/engineering specs are nothing but a series of dimensions,sizes,percentages,measurements, etc. |
http://www.thesamba.com/vw/forum/viewtopic.php?t=338946&highlight=
70 KG Coup
83 Westy Waterboxer |
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djkeev
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Joined: September 30, 2007
Posts: 32989
Location: Reading Pennsylvania
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| Posted: Sun Jun 21, 2015 11:41 am Post subject: |
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| Snort wrote: |
It seems you do grasp my point. Now you are making at least an attempt to flow fuel through the screen rather than pass light. A better test would be running your fuel pump when the tank is low enough so that fuel is actually flowing through the lower half of your screen and see how it performs.
I also think that it's reasonable to pro-actively replace an aging fuel tank that has visible signs of corrosion such as your photos indicate, but not for fear that the factory installed screen is poorly designed and must be eliminated. You're advocating tanks with no screens based on the assumption that what, your rusty tank has a clogged screen? It seems to me that if it actually is clogged then it was doing an adequate job as designed. |
Well, that operating test is never going to happen.
I feel as if I'm on trial for dissecting a fuel tank and reporting my findings.
Who else has bothered to do this even?
I was humoring myself with checking the porosity of the membrane.
It is as plain as the nose on one's face that the screen is clogged.
Look at the photo, the translucent white areas are plugged and it has a few holes that still let fuel pass. The clogged screen is also not rust. It would be brown.
I'm advocating that fuel tanks screens are stupid and only installed today as a cost saving method by manufacturers dropping in a pump/filter combo in one fell swoop! No harder than putting in a fuel gauge on the line...... DONE!!!
This doesn't make it better by a long shot. It only makes it cheaper but becomes a long term service issue For future owners.
Why VW chose to install a screen here mystifies me unless it is simply the long tradition of screens being installed on the earliest Type I units.
There are many problems with this tank design, the screen being but one of them.
Over the years I've yanked out a fair number of clogged submerged pump screens for replacement or cleaning. ........ Dumbest design EVER!!!
Some designs require dropping the tank. Grrrr!
I've also seen a fair quantity of fuel pickup lines with a sock over them. My guess is to prevent chunks from getting sucked into the fuel line..... I get that.
The fine mesh used on the sides baffles me with a larger screen size on the top?
At least with the submerged pump designs you CAN access and service in tank screens unlike this BOZO design.
I Believe that Light reveals much..... My photo illuminated by a light CLEARLY reveals a mostly clogged fuel screen.
Why you don't see this I just don't grasp but..... We all see things from a different perspective I guess.
No problems.... I disagree is all.
What 30 year old fuel tank is not decomposing?
How do you even check?
Who bothers to check?
It isn't until issues arise that problems areas are looked for.
There is no way that 300 liters per hours are passing through this. That is roughly 79 Gallons per hour.
Dave
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Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473
Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537
Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert
Last edited by djkeev on Sun Jun 21, 2015 3:29 pm; edited 1 time in total |
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Wildthings
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| Posted: Sun Jun 21, 2015 9:40 am Post subject: |
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| Snort wrote: |
| It seems to me that if it actually is clogged then it was doing an adequate job as designed. |
The screen is obviously designed to be somewhat self cleaning, but at some point it no longer seems capable of doing this. I know that the stuff that builds up in the early cube prefilters doesn't look like anything to the naked eye, but does clog up the filter quite well, so I would suspect that the same stuff can reduce flow through the screens in the tank.
The FI'd Bay Window buses don't have screens in their tanks and don't seem to have problems until the tanks become very rusty inside or have lots of foreign matter sloshing around in them even though the system is quite similar to the early Vanagon setup. |
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Snort
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Joined: April 02, 2005
Posts: 1964
Location: Seattle, WA
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| Posted: Sun Jun 21, 2015 8:04 am Post subject: |
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It seems you do grasp my point. Now you are making at least an attempt to flow fuel through the screen rather than pass light. A better test would be running your fuel pump when the tank is low enough so that fuel is actually flowing through the lower half of your screen and see how it performs.
I also think that it's reasonable to pro-actively replace an aging fuel tank that has visible signs of corrosion such as your photos indicate, but not for fear that the factory installed screen is poorly designed and must be eliminated. You're advocating tanks with no screens based on the assumption that what, your rusty tank has a clogged screen? It seems to me that if it actually is clogged then it was doing an adequate job as designed. |
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alaskadan
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Joined: January 09, 2013
Posts: 1938
Location: anchor pt. alaska
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| Posted: Sun Jun 21, 2015 7:58 am Post subject: |
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| Maybe you could also repeat that rube-ish test with the portion of screen from the top of the pickup too. Though its pretty obvious that screen was loaded up with tank sealer. |
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djkeev
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Joined: September 30, 2007
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Location: Reading Pennsylvania
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| Posted: Sun Jun 21, 2015 7:34 am Post subject: |
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Well.......
I got to wondering, how pourous is that filter screen?
I cannot scientifically measure the volume that passes through but I can by simple observation SEE what passes through.
I cut out one of the filter screens and using duct tape strengthened the edges and formed it into a slight bowl shape.
I know that the adhesive on the tape has a very short half life in gasoline so this is a one shot deal.
I wondered if the screen has a residue from sitting that gas will cut away?
Anyway, I placed my bowl over a small shot glass and then using a straw and finger over the open end siphon transferred some fuel (Shell E85, oxygenated, unleaded regular) to the filter bowl.
What did it do?
It filled the bowl and then slowly.... Ever so painfully slowly seeped through the screen, not unlike water seeps through coffee grounds to make coffee.
Rube Goldberg flow test results?
Fail!
Even if one were to suck fuel through this membrane, it would be hard going.
Dave
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Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473
Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537
Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert |
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djkeev
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Joined: September 30, 2007
Posts: 32989
Location: Reading Pennsylvania
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| Posted: Sun Jun 21, 2015 5:43 am Post subject: |
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| Snort wrote: |
I appreciate what you're doing here but I don't buy the visual light test you are doing on that filter unless you are using that light show to demonstrate a flow problem that you confirmed by some other test with fuel not able to flow through that lower screen section. By your reasoning the fuel would only flow through the top part of the orange screen and when the fuel level got below the top it stopped flowing. Was this actually happening to you?
Remember those baby bottle nipple commercials? They often used animations to try to convince you that there was a problem with old fashioned nipples so that you would rush out and buy their nipple for twice as much money, using that baby screaming as a guilt factor, you bad bad parent. Your light test seems more like that baby cartoon trying to demonstrate a problem where possibly none exists. |
Nope, no confirmed problem for I've never driven this car with this tank installed.
So,
When you look at my inlet screen photo it begs to be asked how you think fuel with this screen would get to the fuel pickup well at the rapid pace that a 300 liter per hour pumping rate would require once the fuel level dropped below the top screen.
I haven't any flow rate tests..... Sorry.
The light behind the filter screen is a visual aid I used in an attempt to clearly show how clogged the screen is.
How would you photographically show something being clogged?
Please enlighten me.
Are you saying that you don't think it is clogged?
I fail to grasp your point here.....
Let's say I purchased a used car....... Without ever turning the key I Decide to rebuild the engine. (Not out of the realm of reality for I've actually done this)
When I pull the oil pan I find a spun rod bearing.
Should I reassemble it and do an oil pressure test to verify that there is a problem while the engine is running or can I Simply assume that the bearing is actually bad and that it will exhibit the classic signs of a bad rod bearing when running?
Dave
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Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473
Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537
Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert |
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Snort
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Joined: April 02, 2005
Posts: 1964
Location: Seattle, WA
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| Posted: Sun Jun 21, 2015 5:22 am Post subject: |
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I appreciate what you're doing here but I don't buy the visual light test you are doing on that filter unless you are using that light show to demonstrate a flow problem that you confirmed by some other test with fuel not able to flow through that lower screen section. By your reasoning the fuel would only flow through the top part of the orange screen and when the fuel level got below the top it stopped flowing. Was this actually happening to you?
Remember those baby bottle nipple commercials? They often used animations to try to convince you that there was a problem with old fashioned nipples so that you would rush out and buy their nipple for twice as much money, using that baby screaming as a guilt factor, you bad bad parent. Your light test seems more like that baby cartoon trying to demonstrate a problem where possibly none exists. |
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VanShrugs
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Posts: 39
Location: Vancouver Island
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| Posted: Sat Jun 20, 2015 9:50 pm Post subject: |
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Dave,
Given your observations, I do agree.
The usual, do not assume! As I did here.
An OEM tank with fixed filter baskets [meaning non-replicable]
have a limited life.
Better to have a (replaceable) filter-sock over a fuel [in-tank] pump or filter before and/or after the main fuel pump.
The point here is replaceable when requirred.
VS |
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