Fuel tank not filling….

[Icebox500]

OK, I’ve done some reading and I’m still stumped.

I have a 2 year old tank, all new lines and a nearly brand new filler neck (replaced the old one with a missing check ball). I have a gas gauge that under reports the first half of the tank and does not rise to the top.

Clarifications (edit) The check ball is the only thing that has changed prior to this new behavior.

Also, I did do a test where I opened the cap and tried to start the van but it was truly out of gas. Added 2 gallons from my spare and it started right up.

The problem:
I’m on a road trip and am seemingly unable to put more than 8 gallons into the tank! I confirm that I’m getting 15-16 MPG (loaded Westy). How do I “know” the tank is empty? I ran out of gas twice by trusting that it was “full” and the gauge was off (I carry 2 spare gallons).

The last time I ran out, I hadn’t even hit the “red zone” yet (about an 1/8th above red). Prior to the troubles, I could trust the gauge and the bottom half of the tank. The last time I ran out (today) I could hear the fuel pump start to complain just before running out of gas. I (think) I’m convinced I’m not getting a full tank.

My fill technique:
Fill it slowly. Let it burp, try to top it off… it takes only a tiny bit more and there is gas clearly visible. At the top of the tube.

This experience is all new to me in this van I’ve been driving for 2 years and I’m a bit puzzled on how to resolve this new issue.

Thanks and sorry if I’m missing some magic post somewhere about a resolution.
_________________
87 Westy 2WD “Van Geaux”
2.2 Rebuilt WB
AZ Transaxle + Peloquin Manual Transmission
GW lift springs, solar, Burley front disc, etc...

New Orleans, LA (previously CO, WA, and CA)

Past
87, 90 Westys
64, 65 splittys + various air cooled

[fxr]

Perhaps the tank isn't venting properly through the Evap Crap (canister etc). I'd test by removing the input hose to the canister, and trying again.
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Jim Crowther
1984 1.9l EJ22 Westy Wolfsburg Edition
Vespa GTS 300

[zerotofifty]

Id be looking at the vans charcoal canister to see if it or its hoses are clogged. the tank breaths thru this canister, if it is clogged then pressure builds in the tank when filling, which may shut off the fuel dispensing nozzle. Like wise when clogged, if the tank js sealed well with a good seal on the gas cap, a vacuum can be created as fuel is consumed, which can lead to the engine stalling for lack of fuel flow, this symptom might be mistaken as out of gas, when in fact plenty of gas remains in the tank.

You need to assure the venting of the tank via the canister is working.

if it is clogged and the motor stalls do to lack of fuel flow, a temporary fix is to open the gas filler cap to release the vacuum, then upon restart you can drive away a bit more until the vacuum again gets to much for the fuel pump to over come

So check this out, this is referred to as the evaporative system.

I once had a spider nest block the vent on the canister, creating a stalling and fuel filling problem.

A partial blockage may still allow van to run ok, but still be restrictive for filling the gas tank, a more complete block can both effect filling and running.
_________________
Sorry About That Chief.

Give Peace a Chance.

Words to live by.

[Icebox500]

I did do a test where I (when stuck on the side of the road) removed the cap and waited a moment and tried to start the van again. No luck - no fuel. Added 2 gallons from my spare and it started right up.

[Icebox500]

Updated my post to indicate that I did to a vacuum test (as you described) and was still DOA. Added 2 gallons and ran off without a problem. I truly feel like I’m not filling the tank.

[AndyBees]

My first Vanagon was a 1983 Tin-top with the Air-cool engine. Although I had been driving VW Beetles for over 12 years, I had no clue what to expect from the Vanagon. I purchased it for a road trip to Alaska in 1986.

Anyway, with a gasoline jug on board and a very low tank, hanging close to service stations, I drove it until it ran out of gas. I dumped in one gallon of gasoline and drove it to the nearest filling station and filled it until it would hold no more (visible in the filler neck). It held slightly over 16 gallons, counting what I dumped in.

So, from there, I would always fill it to the max to determine the MPGs. I also reset the trip-o-meter. The amount it held was always well within the ball park of the comparable MPGs. And, my 84 with the TDI engine is basically the same.

In your case, it is possible the vent system is compromised with maybe a kinked vent pipe. How many miles are you getting on a fill-up? Do you use the Trip-o-meter to aid in guessing about how much fuel you have left?

One last thing, on a steep hill and a low tank, it is possible the Fuel Pump will begin sucking air. This has happened to me with my 84. And, I am suspect of the aftermarket fuel tank, maybe the pickup tube is not close to the bottom of the tank as in the OE fuel tank.
_________________
'84 Vanagon Tin-top, ALH TDI, two trips to Alaska, 2014 & 16. 1989 Tin-top unmolested.
1983 Air-cool, 225k miles, 180k miles mine, seven trips to Alaska from 1986 thru 2003. 1975 Bay hopeful.

[Icebox500]

Reasonable questions (and a good story).

According to the 7-8 gallon fill ups, I’m getting what is expected, 15-16 MPG.

While it could be a bad vent situation, I’m doubting it since I can pull the cap and the vehicle is still “out of gas”. Frankly; I think it’s really out of gas and something is off after the new check ball.

[Ahwahnee]

I seem to recall some cases of the in-tank pickup coming loose and thus unable to access the last few gallons.

That may seem counterintuitive since the outlet is right there at the bottom corner of the tank but I think it's a bit more complicated than that.

[zerotofifty]

[Icebox500]

An interesting theory for sure and one that’s a pain in the rear. I’ll keep an eye on that and drop the tank if I must.

[AndyBees]

Take a look at this Thread

https://www.thesamba.com/vw/forum/viewtopic.php?t=630469
_________________
'84 Vanagon Tin-top, ALH TDI, two trips to Alaska, 2014 & 16. 1989 Tin-top unmolested.
1983 Air-cool, 225k miles, 180k miles mine, seven trips to Alaska from 1986 thru 2003. 1975 Bay hopeful.

[zululep]

The check ball seems to be the only independent variable here. Sounds like you replaced it very recently, like right before your trip? Do you know if the tank has filled properly since you installed the new check ball? Even if you think it has, I'd suspect the check ball. You might want to remove the filler neck, remove the check ball, reinstall the filler neck and see if that resolves the issue. I don't have one on my '84 (early vans didn't have them) so I'm not sure how it works or why it's there. My van has never puked gas out the neck or blown up, so I'd presume you don't NEED one. When you get home you can dig into it a little more deeply. Good luck.
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1984 Westfalia with Bostig Zetec

[Icebox500]

Thanks for your reply. I agree, it’s the odd man out and I suspect something there too.

Once we get home, that’s something I’m going to take a look at.

Not familiar with them either, frankly but it’s the latest variable and the only one that’s is timed right.

[Icebox500]

Appreciate all the responses and thoughts. Seems I’ll need to take a more serious look when we get home. May actually have more than one cause to this oddity.

Thanks
_________________
87 Westy 2WD “Van Geaux”
2.2 Rebuilt WB
AZ Transaxle + Peloquin Manual Transmission
GW lift springs, solar, Burley front disc, etc...

New Orleans, LA (previously CO, WA, and CA)

Past
87, 90 Westys
64, 65 splittys + various air cooled

[?Waldo?]

It's not uncommon for the tube going from filter to tank outlet to develop a leak. When that happens, the tank will only flow down to the point of the leak (e.g. at 1/2 or 1/3 of a tank). The rest of the fuel just remains in the tank. That happened to me in my '91. It would only accept 7 or 8 gallons and would "run out of fuel" when the tank was still ~1/2 full. Replacing the tank is the simple solution.

[AndyBees]

[my3bugs]

couldnt you fix just fix the tube instead of replacing the tank ? im not faniliar at all with Vanagons .

[AndyBees]

[dhaavers]

[my3bugs]

OK silly me !!! like i said i am not familiar with these and i see what you mean now !!! thanks steve
un serviceable !!!