Home » Public Forums » GMCnet » Help me understand vapor lock
| Re: Help me understand vapor lock [message #209601 is a reply to message #209388] |
Sun, 02 June 2013 07:26   |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
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Well in doing some research on this I learned something...well learned a lot actually between here and the interpipes thingie.
The main thing I learned was that E85 isn't what I thought it was. Currently most every gas pump has a 10% Ethanol added. I assumed that E85 was 15% Ethanon. NOOOOOOO E85 is 15% GASOLINE!
Really interesting E85/Gas comparison test done by the Edmunds folks:
]http://www.edmunds.com/fuel-economy/e85-vs-gasoline-comparison-test.html" target="_blank]
By the way, according to Wiki, the boiling point of pure Ethanol is 173 F. Couldn't find anything specific on the boiling point of 'regular' crapanol because it varies with altitude.
Also some of the antique car boys are adding 5% kerosene to their tanks. It lowers the octane but raises the boiling point and only works with lower compression engines. Some prewar cars with 5:1 types compression can handle up to 25% kerosene. Not proposing anything just an interesting footnote.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
[Updated on: Sun, 02 June 2013 07:31] Report message to a moderator |
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| Re: Help me understand vapor lock [message #209609 is a reply to message #209602] |
Sun, 02 June 2013 09:42 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
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| winter wrote on Sun, 02 June 2013 07:28 |
The common rule for preventing vapor lock was to keep it below about 130 F. That rule must be for older fuel. The new fuels (summer or winter blend) have a big off gas at about 105 F and then another around 115 F to 120 F. ...
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So if that is the issue. The question becomes this:
How can we get/keep the fuel under 105?
Obviously under hood temps and over road temps are going to FREQUENTLY exceed 105 and much more.
Seems to me there may be only four possible solutions
1- Moving fuel pumps to the tank
2- Routing fuel lines away from heat sources (although I can't see how that would help if air and road temps are much over 100 and/or altitude is over 3000'
3- Mechanical cooling fuel prior to it getting to the engine (using the AC compressor in some manner to cool the fuel prior to it getting to the carb/throttle body)
4- Evaporative cooling of the fuel/fuel lines.
Keep in mind that I have never encounter vapor lock on a GMC and only rarely in my life. That said, it's my nature to noodle on problems. Once in a while a idea bears fruit.  
What if:
1- We could wrap the fuel line from the tanks forward with some type of 'soaker hose' supplied by water from our fresh water tank? Would not the evaporation of the water by the hot air/reflected heat not cool the fuel in the line and therefore keep upstream components cooler?
2- We could spray the fuel pump/carb/throttle body with a water mist. I have a misting nozzle from a humidifier that produces a very, very fine mist.
I know that raising the carb causes interference with the hatch cover but there are several solutions to that short of raising the hatch including going to a thinner yet just as strong material. Assuming we could raise the carb a half inch or so what if we made a phenolic spacer to isolate the carb mechanically from the engine heat. We could then build an air filter cover surround that totally wrapped the carb. This would keep ambient air flowing around the carb. Moving the air intake to a source of cooler air would help also. Finally, the same water mister could be used to spray the carb/throttle body. Any excess water would just evaporate away.
It would be great if there was a way to test this stuff.
Just thinking with my fingers....
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
[Updated on: Sun, 02 June 2013 09:42] Report message to a moderator |
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| Re: [GMCnet] Help me understand vapor lock [message #209610 is a reply to message #209605] |
Sun, 02 June 2013 09:43 |
James Hupy
Messages: 6806
Registered: May 2010
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Use 87 octane NO ALCOHOL FUEL. Can't find it? Gee, imagine that. You
probably will have to go to 92 octane to get No ALCOHOL. Most octane
booster products are high in alcohol. Octane is an arbitrary and capricious
scale that loosely correlates higher numbers to lower A.K.I. (antiknock
index.) Remember, the current scale is a combination of two different
methods of testing. Used to be the A.P.I. (American Petroleum Institute)
and the Society of Automotive Engineers, worked out the scale using very
carefully monitored scientifically based testing using a very special
variable compression ratio test engine. Today, the U.S. Government just
tells us what it is. Gee, which one do I believe?
Jim Hupy
Salem, Or
78 Gmc Royale 403
On Jun 2, 2013 6:42 AM, "Steve Weinstock" <steve.weinstock@cox.net> wrote:
>
>
> So...
>
> Acknowledging that today's fuel supply isn't as good as it used to be,
> what's the consensus on a fuel grade to use ??
>
> Regular, Plus, Premium... ??
>
> And what about octane booster ??
>
> Steve W
> Southern California
> 1973 23'
>
>
> _______________________________________________
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| Re: [GMCnet] Help me understand vapor lock [message #209616 is a reply to message #209409] |
Sun, 02 June 2013 10:41 |
Steven Ferguson
Messages: 3447
Registered: May 2006
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Tiny bubbles, in the line.....couldn't help myself Jim. I had this
happen one time to me and that was enough to make me do something about
it. I tore out all the fuel line ahead of the bellhousing and rerouted the
line up the firewall. I insulated it with the same foam tubing you use to
prevent pipes from freezing and then wrapped it with Reflectix tape. I ran
the fuel line under the linkage down the length of the intake, to a
pressure regulator.
Here's a pic:
http://www.gmcmhphotos.com/photos/engine-replacement/p25704-p1020636.html
Never had another episode of VL.
Steve F.
On Fri, May 31, 2013 at 8:13 AM, James Hupy <jamesh1296@gmail.com> wrote:
> Vapor lock, what it is and isn't. It starts with tiny bubbles, kinda like
> champagne bubbles, in the liquid fuel system. These bubbles occur because
> some of the hydrocarbon components of modern motor fuels are lighter than
> air at 120 -150 degrees farenheit, and try to exit the fuel stream. When
> this occurs the fuel bubbles (boils) . If this occurs in the fuel lines or
> tanks, large amounts of expansion occurs. When even the best high pressure
> fuel pumps encounter bubbles in the fuel, all they do is compress the
> bubbles, NOT MOVE THE FUEL THROUGH THE LINES!!! That is when the operator
> notices a lack of throttle response and bogging when throttle is applied.
> How do we fix it?? The fix is in the FUEL, not the Gmc. Take the ethanol
> out of the FUEL. Raise the Reid Vapour Index of the FUEL. How likely is
> that happening soon? Not very. So, now what? Drive in the cool part of the
> day helps. Electric "pusher type" fuel pumps help. Keeping your fuel tanks
> full helps. Blocked exhaust crossovers helps. Lower engine compartment
> temperature helps. But nothing we try will TOTALLY SOLVE vapor lock. Just
> my experienced opinion.
> Jim Hupy
> Salem,Or
> 78 Gmc Royale 403
> On May 31, 2013 7:09 AM, "Kerry Pinkerton" <Pinkertonk@mchsi.com> wrote:
>
> >
> >
> > tphipps wrote on Fri, 31 May 2013 09:00
> > > I don't like the idea of having any fuel within the passenger
> > compartment. ...
> >
> >
> > I don't either Tom. BUT, if it helps, there are ways to isolate and
> > insulate a fuel CELL that could be cooled by the AC system and still be
> > kept OUTSIDE the passenger compartment. The question is, would it help?
> > --
> > Kerry Pinkerton
> >
> > North Alabama, near Huntsville,
> >
> > 77 Eleganza II, "The Lady", 403CI, also a 76 Eleganza being re-bodied as
> > an Art Deco car hauler
> > _______________________________________________
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> >
> _______________________________________________
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--
Take care,
Steve
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| Re: [GMCnet] Help me understand vapor lock [message #209617 is a reply to message #209462] |
Sun, 02 June 2013 10:44 |
Steven Ferguson
Messages: 3447
Registered: May 2006
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Howard, that was next on my list.
Steve F.
On Fri, May 31, 2013 at 4:49 PM, Howard <hnielsen2@cox.net> wrote:
> Talked about this before.
> I installed aluminum diamond plate under the tanks with a kick up on the
> leading edge.
> It's attached to the frame with self tapping screws.
> Works excepted on the VERY hottest of days with the black top at over 100
> degrees at altitude over 4,000 feet.
> We are fighting junk gas, hot pavement and altitude.
> I received a news letter today from S E M A we will have E-15 by the year
> 2022 unless we stop it.
> We all need to back bills H.R. 875 and S 344 bought supported by S E M A.
> Get after your local lawmakers.
> This year Florida, Maine, West Virginia and Oregon have taken the lead in
> dealing with the ethanol issue.
> Give them an "att'a boy or girl" for putting the brakes on ethanol in our
> fuel
> Sorry I do not have photos of the diamond plate our GMC
> Thanks
> Howard
>
> All is well with my Lord
>
> On May 31, 2013, at 11:16 AM, Johnny Bridges <jhbridges@ymail.com> wrote:
>
> > pure-gas.org is Your Friend. I can usually make a trip on gasoline,
> and when I do, I have no problems and an extra 1 mpg (that's a ten percent
> increase). The biggest problem I have is a trip to San Antonio most years
> in mid - July. Out og Houston, there's no gas to be had. Go figure. I
> have to make the foirst part of the homebound trip eaerly in the morning,
> and get to East Tejas before it gets too hot. Even then, it will lock and
> die when stopped. Moving, it survives.
> >
> > --johnny
> > '76b 23' transmode norris
> > '76 palm beach
> >
> >
> > ________________________________
> > From: Carl Stouffer <carljr3b@yahoo.com>
> > To: gmclist@temp.gmcnet.org
> > Sent: Friday, May 31, 2013 12:58 PM
> > Subject: Re: [GMCnet] Help me understand vapor lock
> >
> >
> >
> >
> > I have done everything BUT install in tank fuel pumps in an effort to
> cure vapor lock. I have; installed a heat dissipator under the carb,
> installed Jim B's insulated, braded fuel line from fuel pump to carb,
> installed a cold air intake from the grille to the air cleaner, installed
> an electric fuel pump right back at the tank on the aux tank, installed a
> Gary Rockwell intake manifold, installed a severe duty fan clutch, etc,
> etc. I STILL have vapor lock on occasion when the temps are above 90 and I
> am climbing or otherwise putting the engine under extreme load. The
> closest thing to a cure has been the electric fuel pump.
> >
> > On our recent trip to Texas, we drove from Tucson to Las Cruces, about
> 280 miles, in the late afternoon and evening. Not much trouble then, but I
> did have to turn on the electric pump several times. Hal Told us where an
> ethanol free station was in town and we filled up there for the next leg of
> the trip, bypassing El Paso on the north side and proceeding to Carlsbad
> Caverns. There are several good climbs along that route, including the
> Guadalupe Mountains. For the first time since I got the coach, I had NO
> vapor lock issues whatsoever. I turned on the electric pump while pulling
> the grade up the Guadalupe mountains as a precaution, but probably would
> not have needed it.
> >
> > James is right, the best cure for vapor lock is ethanol free gasoline.
> Since that doesn't seem like a viable option in most parts of the country,
> Emery's in tank fuel pump option would seem the be a good alternative as
> well.
> >
> > By the way, I gassed up in Las Cruces on the way home, at the same
> e-free station, and had considerably more gas in the tanks when hen I got
> home that I did covering the same ground on the way TO las Cruces. The
> coach also had noticeably more power on the e-free gas.
> > --
> > Carl S.
> > '75 ex Palm Beach
> > Tucson, AZ.
> > _______________________________________________
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--
Take care,
Steve
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| Re: [GMCnet] Help me understand vapor lock [message #209632 is a reply to message #209625] |
Sun, 02 June 2013 16:50 |
Neil
Messages: 271
Registered: July 2007
Location: Los Angeles and Magalia, ...
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While I am sure fuel can and does boil in the low pressure environment of the fuel line, there is no doubt it also boils in the tank - I have heard it and experienced the effect (gas and vapor shooting out the cap when opened).
After a bad problem a few years back with vapor lock while going cross country, I had the tanks dropped, spray coated with insulation (lizard skin) put on diamond plate heat shields and used oversized braided steel fuel hose inside an insulated cover.
http://www.gmcmhphotos.com/photos/gas-tank-heat-shields/p35240-gas-tank-heat-shields.html
or
http://tinyurl.com/n6w3ykb
Plus I have a switchable electric fuel pump at but not in the tanks.
I have not had a problem since.
Neil
76 Eleganza now sold
Los Angeles
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| Re: Help me understand vapor lock [message #209653 is a reply to message #209388] |
Sun, 02 June 2013 20:06 |
WayneB
Messages: 233
Registered: July 2008
Location: Ontario, Canada
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I have been experiencing vapour lock from time to time in my GMC (even with Howell FI) and was contemplating mounting a Jaguar V12 fuel cooler in the A/C line.
They work great on my XJ12, and the Jag uses the same R4 AC compressor as the GMC.
1976 23' GMCII By Explorer
[Updated on: Sun, 02 June 2013 20:06] Report message to a moderator |
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