Home » Public Forums » GMCnet » Vapor Lock (yes, again)
| Vapor Lock (yes, again) [message #88153] |
Fri, 11 June 2010 23:44  |
Rick Denney
Messages: 430
Registered: January 2004
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I'm up on the mountain with the coach, and had some interesting vapor lock problems on the trip up here. Thought I'd pass it along to add data points to the collective consciousness.
First incident: After having driven about 75 miles on a hilly I-81, speeds 65-70, I exited in Harrisonburg and came to a stop at a traffic signal. After about 45 seconds of waiting, the light turned green. The road climbed from the intersection and I gave it fairly hefty throttle. After about 200-300 feet, I lost power in classic fuel starvation symptoms and had to back the throttle way off to keep the engine from dying. After about 15 seconds, it was fine again. No problems with other signals on that route.
But then, I stopped at a grocery store and idled for several minutes while making a radio contact. Second incident: While talking on the radio, the engine died. It would not restart on either tank. I went in and did my shopping, wondering if I'd run out of gas (which didn't seem possible--I figured I had at least 20 gallons in the tank). Shopped for about half an hour, came back out, and the engine fired right up without the slightest issue. Drove it one block to a gas station and put in 31 gallons--just as expected (my tank capacity is 54 gallons).
Fuel was from last fall, bought in September and probably still a summer blend.
Drove it up the mountain, which is a climb of about 3500 feet in 15 miles, including the last 500 feet of climb on a rocky forest service road at just above crawl speed, and had no further issue, except maybe a bit of a burble when starting up after a pause at the start of the dirt road to raise the rear.
On the fan clutch front (and it may be related), temperature would not maintain at 180 on the highway with the AC going. The clutch cycled in every little while, and just as before, the coolant temperature immediately starting dropping and the fan would go off less than two minutes later with the coolant temp at 178. Coolant temps when the fan came on ranged from 188 (gradual warmup) to 200 (fast warmup on a steep climb).
The clutch ran much less often on the big climb--I had turned the AC off. The AC is definitely adding to the problem, as one would expect.
Ambient temps were in the 90-degree range on the Interstate, and probably in the upper 70's on the mountaintop. It was warm.
Rick "deeply annoyed by this vapor lock thing" Denney
'73 Glacier 230 "Jaws"
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| Re: [GMCnet] Vapor Lock (yes, again) [message #88178 is a reply to message #88171] |
Sat, 12 June 2010 06:46  |
Ken Coit
Messages: 151
Registered: November 2005
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Sounds like the same sort of problem I had a few years ago. Glad to hear I
am on the right track:
"new" carburetor
new exhaust system
two new fuel pumps, added an electric, replaced the wrong mechanical,
clean filters
better engine compartment circulation
and to make sure I can stop if the engine dies anyway:
electric vacuum pump
vacuum reservoir
and a vacuum gauge on the tank to make sure it is going to contribute to the
solution, not the problems.
Some boats have a "day tank" for diesel. I am thinking that a real reserve
tank might be a good idea.
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Ken Coit, ND7N
Raleigh, NC
Parfait Royale
1978 Royale Rear Bath, 403, 3.07
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| Re: [GMCnet] Vapor Lock (yes, again) [message #88181 is a reply to message #88179] |
Sat, 12 June 2010 07:19 |
John Sharpe
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
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| Quote: |
Eugene,
> Electric fuel pump is not the solution.
>
you have some other problem. not vaporlock
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I tend to agree. With all the new additives nobody cares about how carburetor vehicles run, so the fuel vaporization could be getting critical even under a few # of pressure. If it is vapor lock add a fuel pressure regulator at the carburetor and run the return line back to the fuel filler pipe just like we do with the TBI. If you still encounter problems then you can boost the pressure from the pump.
John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
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| Re: [GMCnet] Vapor Lock (yes, again) [message #88201 is a reply to message #88181] |
Sat, 12 June 2010 08:10 |
Sandra Price
Messages: 709
Registered: May 2006
Karma: 1
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John, Bob had wanted me to tell Charles the same thing. So ditto!
Sandra
On Sat, Jun 12, 2010 at 7:19 AM, John Sharpe <johnasharpe@earthlink.net>wrote:
>
>
> Quote:
> > Eugene,
> > > Electric fuel pump is not the solution.
> > >
> >
> > you have some other problem. not vaporlock
>
>
> I tend to agree. With all the new additives nobody cares about how
> carburetor vehicles run, so the fuel vaporization could be getting critical
> even under a few # of pressure. If it is vapor lock add a fuel pressure
> regulator at the carburetor and run the return line back to the fuel filler
> pipe just like we do with the TBI. If you still encounter problems then you
> can boost the pressure from the pump.
> --
> John Sharpe
> Humble,TX
> '40 Ford Deluxe TBI
> '78 Eleganza TBI
> '78 Royale TBI
> mailto:johnasharpe@earthlink.net
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--
IN GOD WE TRUST!
Sandra and Bob in the 51st Year of our State of Marriage
“Life’s a Trip” in “The Roadhouse”
’73 Painted Desert
Huntsville, TX
Finally, all of you, live in harmony with one another, be sympathetic, love
as brothers, be compassionate and humble. Do not repay evil with evil or
insult with insult, but with blessing, because to this you were called so
that you may inherit a blessing. --1 Peter 3:8-9
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| Re: Vapor Lock (yes, again) [message #88202 is a reply to message #88153] |
Sat, 12 June 2010 08:18 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
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fuel pump problems and a ignition module in the distributor going bad can have the same symptoms especially in hot weather.
just something to try.
Fred V
'77 Royale RB 455
P'cola, Fl
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| Re: [GMCnet] Vapor Lock (yes, again) [message #88215 is a reply to message #88212] |
Sat, 12 June 2010 08:57 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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That was Bill Bramlett !
Emery
On Jun 12, 2010, at 7:37 AM, Emery Stora <emerystora@mac.com> wrote:
> Hi Charles
>
> I had reported two or three weeks ago that Bill Bramlret has developed
> an in-tank fuel pump that he says will eliminate the vapor lock
> problems that you are talking about.
>
> He has modified a stock in-tank pump that will fit on the end of our
> existing GMC fuel tank sender / pickup tube.
>
> Pictures are in the mail to me as I write this. I will work with Bill
> to do a writeup for the net.
>
> I plan to put one in each of my fuel tanks. However these are high
> pressure pumps for a fuel injection system so you'd have to use a
> pressure regulator to drop the pressure if you are using a carb.
> Probably also have to have a fuel return line from that regulator as
> those of us using a TBI system have.
>
> I'll be posting more on this topic as I drop my tanks and install
> these.
>
> Electric fuel pumps are good for pushing fuel but don't do as good a
> job sucking up fuel so having them in the tanks eliminates the low
> pressure created between an external pump and the tank which can lead
> to vapor lock at that point.
>
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>
> On Jun 12, 2010, at 5:38 AM, Charles <gcw13@sbcglobal.net> wrote:
>
>>
>>
>> Eugene,
>> Electric fuel pump is not the solution. I had both manual and
>> electric and still had vapor lock. Lock on manual and electric would
>> only sometimes take care of the problem. I removed manual pump and
>> went strictly with electric. Still have problem. Electric pump is
>> just forward of the tank selector valve about
>> three inches. What do we do now? I am ready to try almost any thing
>> and I don't have mountains.
>> Charles
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| Re: [GMCnet] Vapor Lock (yes, again) [message #88221 is a reply to message #88212] |
Sat, 12 June 2010 09:38 |
Charles
Messages: 455
Registered: January 2004
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Emery,
I saw your previous post and I look forward to your
report. Except for the return line that sounds like a
simple fix. Something I can do myself and probably
afford. If I had known I would have this money pit
GMC when I was working I would have put more
away.
Charles
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Charles Wersal
Duncanville, Texas
26 foot 1975 Glenbrook
Pandora's Box
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| Re: [GMCnet] Vapor Lock (yes, again) [message #88247 is a reply to message #88176] |
Sat, 12 June 2010 12:39 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Electric pump in a wrong location is worthless.
If your not running with an aux. electric pump don't complain.
With the new blend of fuels the way they are, you need to keep the
fuel under pressure. Look at new cars. Pump is in the tank for that
reason.
Our tanks are very low to the ground, tremendous surface area . The
heat from the hot road surface radiate into the tank, Like boiling
water, less pressure, lower the boiling point.
On Sat, Jun 12, 2010 at 4:38 AM, Charles <gcw13@sbcglobal.net> wrote:
>
>
> Eugene,
> Electric fuel pump is not the solution. I had both manual and electric and still had vapor lock. Lock on manual and electric would only sometimes take care of the problem. I removed manual pump and went strictly with electric. Still have problem. Electric pump is just forward of the tank selector valve about
> three inches. What do we do now? I am ready to try almost any thing and I don't have mountains.
> Charles
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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www.appliedgmc.com
1-800-752-7502
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| Re: Vapor Lock (yes, again) [message #88250 is a reply to message #88153] |
Sat, 12 June 2010 13:48 |
LYNN L
Messages: 140
Registered: March 2005
Location: Pearland TX.
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Have any of you ever tried installing a fuel reservoir on the firewall mounted low with an electric pump supplying the entry on the top of the unit and the exit on the bottom. I live where it is usually 95 in the shade and it cured my vaporlock problems for good. I removed the stock mechanical pump.. Mine is made from stainless but you can probably find some already made for fuel injection applications.
Lynn L
76 Eleganza Cad.500
Pearland TX.
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| Re: Vapor Lock (yes, again) [message #88290 is a reply to message #88153] |
Sat, 12 June 2010 19:47 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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| Rick Denney wrote on Fri, 11 June 2010 21:44 |
I'm up on the mountain with the coach, and had some interesting vapor lock problems on the trip up here. Thought I'd pass it along to add data points to the collective consciousness.
Rick "deeply annoyed by this vapor lock thing" Denney
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Rick,
I posted this on one of the other vapor lock discussions so it may be repetitious:
Has anyone here tried fuel coolers? They make me a little nervous, as you sure would want them protected. I also wouldn't want one in front of the radiator, because if it got hit by a rock, gas would be sprayed by the fan.
The first one here doesn't look like it could provide much, but the cost is right.
http://www.google.com/products/catalog?hl=en&rlz=&q=fuel+cooler&um=1&ie=UTF-8&cid=9740907708678323321&ei=1ZoTTKqPC6XinQe7uoiCD g&sa=X&oi=product_catalog_result&ct=result&resnum=2&ved=0CCMQ8wIwAQ#
Second is more like a powersteering cooler. I considered one when running my first TBI and the tanks built so much pressure. (By the way, I believe a cap in good shape is set to pop off at 3 lbs. The system also lets air back in to the tanks so there is a little vacuum but not extensive.)
http://www.amazon.com/Flex-lite-4136-Fuel-cooler/dp/B000CNLD9C
You can do your own search on Google: Fuel cooler
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] Vapor Lock (yes, again) [message #88770 is a reply to message #88247] |
Tue, 15 June 2010 21:55 |
Rick Denney
Messages: 430
Registered: January 2004
Karma: 0
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| gene wrote |
no electric pump?
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| jimk wrote |
Electric pump in a wrong location is worthless. If your not running with an aux. electric pump don't complain.
|
How many times have I written about my fuel arrangement? And I thought I had CRS.
I have a Carter 4070 mounted just downstream of the selector valve. The mechanical pump is bypassed completely. The tanks are Cinnabar replacements. I have two filters inline upstream from the selector valve, and one inline in the AN-6 aircraft hose that connects the hard tubing on the crossmember to the carb. The filter case in that spot is wrapped in foam insulation with a foil cover.
So far, the only idea I've heard that makes sense is putting a return line from a pressure regulator to allow continuous recirculation, assuming the fuel in the tanks themselves is not excessively vaporizing.
But "boiling" in the tanks or the hoses between the tanks and the pump does not fit the symptoms. The engine displays fuel starvation symptoms after about 200 feet after a startup. The engine doesn't use fuel fast enough to get to that bit. The engine should run on what's in the float bowl for longer than that.
And my carb is a DP rebuild and it is sitting on an RPM manifold with no crossover. Thus, the carb should not be experiencing excessive heating from the manifold. But that doesn't mean it isn't getting hot otherwise. That engine compartment is a hot place.
I think it must be boiling right in the carb or very close to it. I'm only burning two or three ounces of fuel before the symptoms appeared in my first situation, which is similar to what I have experienced before.
Rick "cause and effect" Denney
'73 Glacier 230 "Jaws"
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| Re: [GMCnet] Vapor Lock (yes, again) [message #88797 is a reply to message #88770] |
Wed, 16 June 2010 06:48 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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>
> gene wrote
> > no electric pump?
>
>
> jimk wrote
> > Electric pump in a wrong location is worthless. If your not running with
> an aux. electric pump don't complain.
>
>
> How many times have I written about my fuel arrangement? And I thought I
> had CRS.
>
we often forget that with 300 to 400 folks on line
and
8000 GMC owners on the road
that we often do not know the configuration of a specific individual
gene
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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