Oregon gasoline and hot weather

[Wildthings]

Yesterday my wife picked me up at the Portland airport in the 100°F+ heat of the afternoon. She had gotten stuck in traffic on Airport Way where it intersects with I-205, taking 40 minutes or so to go a mile or two. When she picked me up I commented that the car smelled of gas. On leaving the airport and entering the stalled traffic again the idle became erratic and the engine began to stall, it was hard to restart and had to be revved to be kept running.

What was happening is that without airflow under the rig the gas in the tank had gotten hot enough to boil, but once we got out on the open road the tank cooled and the problem resolved itself. The Oregon summer gas blend is just not suitable for the most extreme heat that a PNW summer can deliver. I and many others have had problems with carbureted rigs on hot days, but this is the first time I have had problems with a FI rig on a roadway. I have had similar problems before with my Toyota truck when using it for a prolong time as a tractor in extreme heat.

If you think that you may be experiencing this problem, do not remove the fuel cap, as with the pressure in the tank reduced the fuel may boil violently spewing gas out the fill.

[danfromsyr]

had an isuzu trooper once where the bad repair of exhuast flexpipe fell off and pointed directly at the steel fuel tank.

was wondering what sounded like a tea kettle whistle at a stop light.

drove on.


next stop light same tea kettle.

got out and discovered it was my gas cap.
opened the gas cap (foolish in hindsight) and WHOOOOOOOssssshhh
no fuel but a hot air blast from the compressed air/expansion..

we took a walk and let it cool down there on the side of the road..

later repointed the flex pipe and took it home to repair.
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[E1]

Wow. Can't wrap my head around this one, how could it get to its boiling point of approximately 180 degrees?

The running condition sounds identical to the few times we've vapor-locked. Not discounting you one bit Bud, just baffled how the temp could get to a point of boiling.

I'd be inclined to think if not vapor lock, then perhaps it was over-pressurized and isn't venting properly.
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[Wildthings]

[E1]

Thank You, that does make sense now.
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[Vanagon Nut]

I had a very noisy fuel pump then stall at idle and no start in the middle of nowhere OR. This was at higher altitude. Removed fuel cap, "whoosh". Van restarted no problem. I'd assumed a vacuum had been created but in hindsight, I bet I was wrong.

Shouldn't the Vanagon EVAP system vent off pressure? Or, is the rate of expansion too much for a properly functioning EVAP system to handle?

Thanks for the warning Wildthings.

Neil.
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1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[djkeev]

I think that a lot of these old vent systems don't vent well any longer.
The charcoal has turned to go, spiders built webs in the vent, etc.

I bypassed my entire vent collection system and vent into the right frame rail.

Old school.....

Dave
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Stop Dead Photo Links how to post photos

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

[E1]

[Tom Powell]

From the internet:

"Gas doesn't typically "boil", but it does vaporize (evaporate) at anything over 93 degrees F or so. As I understand it, the "boiling point" of regular 87 unleaded is about 181 degrees...but this will differ depending on pressure and what additives are in the gas."

Aloha
tp

[DuaneL]

also from the internet

Not being a pure substance, gasoline has no single boiling point. Instead, the lighter fractions start boiling out at 90-100 degrees F, with more and more evaporated as the liquid temperature increases, until the final, heaviest fractions evaporate in the 300-400 degrees F range. This behavior is called the “distillation curve.” Ethanol boils at 178.5 degrees F, while water boils at 212 degrees F.
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1971 std bug, 1776, ACN Super Stock 34-3, dvda dist, 27x8.50 14 tires

[photogdave]

[lostinavan]

Bro, you should always take 82nd to pdx during high traffic

[Merian]

the charcoal in the canisters will last nearly forever unless you get liquid gas inside there

more likely is that one will burst open 2-3 times per century, spilling the still good granules out
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....

[E1]

How does liquid gas get into the canisters?
_________________
‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[Team WorldTour]

[drj434343]

Hot or boiling gas in the tank and vapor lock may not be mutually exclusive either. The hotter the incoming gas from the tank, the less delta-T remains for the heat soak in the engine compartment.

[Abscate]

[dgbeatty]

We had this problem recently on Mount Diablo here in California. We have wonder gasoline here and it does strange things.
The A/C was running at max with road speed of a bit over 10mph, 100f or a bit higher the road grade was ~~10%.
The only real solution is a fuel cooler such as used by MB since the eighties. The fuel return line is cooled by the low presure A/C line right before it enters the compressor.
I would judge the fuel pump temp to been over 150f, maybe as high as 180f. It was much to hot to touch. I would compare it to a dark colored car hood parked in the sun which often measure over 180f.
I let it set for 45 minutes with a fan blowing on it. Afterwards it was fine.
It was assumed that vapor lock would a thing of the past with electric fuel pumps mounted below or inside the fuel tank along with recurculaing higher fuel pressure systems. The modern gasoline blends have proven that not to be true. In response car companies have steadily increased the fuel pressure, added fuel cooling, and valves that block all flow, due to heat soak, when the engine is switched off. We may need to do some of the same!

[Vanagon Nut]

[dgbeatty]

Vanagon fuel tanks are only good for a few "whooses" when removing the fuel cap. The temp fix is to remove the cannister and whack the ground with it a few times to shack up and loosen the charcoal. Or disconnect the large line on the top. After the maximum number whooses has been exceeded call your favor vendor and order a replacement for your now collapsed fuel tank.