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Eliminating Vapor Lock [message #254741]

Tue, 08 July 2014 16:13

Jeff Marten

Messages: 199
Registered: August 2013

Karma: 1

Senior Member

The Royale has a bit of vapor lock when the ambient temp is over ~85*. Once the ambient temp drops into the 70's there is no issue. A PO has installed an insulated fuel line from the fuel pump to carb. I'm contemplating installing a bypass from the carb back to the tank to keep the fuel moving.
However, I just saw some info on Bdub's pages about vapor lock and using the Carter kit. Assume this has two one-way valves to recirc/bypass the fuel.
How well do these fare against vapor lock?
Alternatively, I have a couple good spare Holley red pumps, and could install one without the recirc/bypass. Any real difference in functionality?
Not looking to do anything more intrusive or costly at this time; too many higher-priority projects this year.

1985 Gulf Stream 34' Sun Stream 1964 Falcon 'Vert 1980 Bradley GTE 1999 Chevy Tahoe 2005 Saab 93 Aero 1987 Suzuki Intruder 1400 1978 Glastron/Carlson CV23

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Re: [GMCnet] Eliminating Vapor Lock [message #254746 is a reply to message #254741]

Tue, 08 July 2014 17:02

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

I would chime in here about vapor lock. The MAJOR CONTRIBUTOR to it is
Ethanol in gasoline. DEPENDING UPON THE AMOUNT OF ALCOHOL BLENDED, winter
vs summer blends, and the ambient outside temperatures, somewhere near 90°
F. you will experience it. Lots of variables here, but cooler fuel helps.
Higher fuel line pressure helps. But be careful with too much pressure,
inlet needle valves in carbs get ineffective above. 9 psi. or so. Fuel
injection helps. BUT NONE OF THE ABOVE THINGS WILL COMPLETELY ELIMINATE THE
ROOT CAUSE. ALCOHOL IN THE FUEL. Keep your tanks nearly full, and fuel up
first thing in the morning. Travel early in the day, or after sundown. We
just completed a 6000 mile trip on route 66. None of the coaches were
affected to the point of stopping, but I and another carb equipped coach
were affected in temps above 100° F. which we saw too often in Tex., N.M.,
AZ. and Ca.
Jim Hupy
Salem, Or (only 91 here today)
78 GMC ROYALE 403
On Jul 8, 2014 2:13 PM, "Jeff Marten" wrote:

> The Royale has a bit of vapor lock when the ambient temp is over ~85*.
> Once the ambient temp drops into the 70's there is no issue. A PO has
> installed an insulated fuel line from the fuel pump to carb. I'm
> contemplating installing a bypass from the carb back to the tank to keep
> the fuel
> moving.
> However, I just saw some info on Bdub's pages about vapor lock and using
> the Carter kit. Assume this has two one-way valves to recirc/bypass the
> fuel.
> How well do these fare against vapor lock?
> Alternatively, I have a couple good spare Holley red pumps, and could
> install one without the recirc/bypass. Any real difference in
> functionality?
> Not looking to do anything more intrusive or costly at this time; too many
> higher-priority projects this year.
>
> --
> 1978 Royale
> Side bath w/rear dinette
> 1964 Falcon 'Vert
> 1980 Bradley GTE
> 1996 GMC K2500 Suburban
> 2005 Saab 93 Aero
> 1987 Suzuki Intruder 1400
> 1978 Glastron/Carlson CV23
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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Re: Eliminating Vapor Lock [message #254750 is a reply to message #254741]

Tue, 08 July 2014 17:44

midlf

Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)

Karma: 1

Senior Member

Recirc systems can get to be a bit of a project. I believe necessary sooner or later. However for quick, cheap and reasonalby effective system Jim Bounds trick of installing a booster fuel pump between the aux tank and the selector valve can't be beat. The pump is powered from the selector valve terminal. If you start getting vapor lock switch to the aux tank. The booster pump will pressurize the system to, hopefully, block the vaporization.

Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI

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Re: [GMCnet] Eliminating Vapor Lock [message #254823 is a reply to message #254750]

Wed, 09 July 2014 09:23

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Steve,

As we say Downunder; "Spot on, Mate!" I've had that setup on Double Trouble for over four years and it works great.

Here's the JimB easy fix for vapor lock.

Install one of the p/n Facet pumps below in the line that comes from the Aux tank to the selector valve. Wire it to the selector
valve. When you switch to AUX the pump comes on and pressurizes the inlet of the mechanical fuel pump. I've used it for the past two
years and it works very well.

DOWNSIDE: if you have a fuel pump with a weak diaphragm it is possible that the pressure from this pump could tear it and fill the
crankcase with fuel.

12 VOLT FACETR CUBE FUEL PUMPS

PART #: 40104
MIN - MAX PSI: 1.5 - 4.0
GPH: 25
INLET/OUTLET THREAD SIZE: 1/8-27 NPT
MIN. DRY LIFT: 12"
CHECK VALVE: NO

Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428

-----Original Message-----
From: Steve Southworth

Recirc systems can get to be a bit of a project. I believe necessary sooner or later. However for quick, cheap and reasonalby
effective system Jim Bounds trick of installing a booster fuel pump between the aux tank and the selector valve can't be beat. The
pump is powered from the selector valve terminal. If you start getting vapor lock switch to the aux tank. The booster pump will
pressurize the system to, hopefully, block the vaporization.
--
Steve

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

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Re: Eliminating Vapor Lock [message #255045 is a reply to message #254741]

Fri, 11 July 2014 08:16

Jeff Marten

Messages: 199
Registered: August 2013

Karma: 1

Senior Member

OK, I'm going to work on installing one of my Holley red pumps tomorrow. Anyone have pics of where the electric pump is generally tied in to the AUX fuel line?

Alternatively, I'm considering just pulling the mech pump and installing the Holley in the main fuel line as my only pump. From what I remember reading about the Holley, it has an internal spring-loaded bypass, so no need for all the one-way valves, tees, bypass loop, and multiple leak point potentials the Carter setup has.

Anyone else running just an electric pump setup with a carb?

1985 Gulf Stream 34' Sun Stream 1964 Falcon 'Vert 1980 Bradley GTE 1999 Chevy Tahoe 2005 Saab 93 Aero 1987 Suzuki Intruder 1400 1978 Glastron/Carlson CV23

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Re: Eliminating Vapor Lock [message #255062 is a reply to message #255045]

Fri, 11 July 2014 10:33

Carl S.

Messages: 4186
Registered: January 2009
Location: Tucson, AZ.

Karma: 13

Senior Member

Jeff Marten wrote on Fri, 11 July 2014 06:16

OK, I'm going to work on installing one of my Holley red pumps tomorrow. Anyone have pics of where the electric pump is generally tied in to the AUX fuel line?

Alternatively, I'm considering just pulling the mech pump and installing the Holley in the main fuel line as my only pump. From what I remember reading about the Holley, it has an internal spring-loaded bypass, so no need for all the one-way valves, tees, bypass loop, and multiple leak point potentials the Carter setup has.

Anyone else running just an electric pump setup with a carb?

I used a solenoid type electric pump. You can kind of see it here:

http://www.gmcmhphotos.com/photos/gas-tank-fuel-line-project-6-10/p34777-gas-tank-clean-up-fuel-line-replacement.html

And here:

http://www.gmcmhphotos.com/photos/gas-tank-fuel-line-project-6-10/p34773-gas-tank-clean-up-fuel-line-replacement.html

Carl Stouffer '75 ex Palm Beach Tucson, AZ. Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member

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Re: Eliminating Vapor Lock [message #255070 is a reply to message #255045]

Fri, 11 July 2014 11:54

roy1

Messages: 2126
Registered: July 2004
Location: Minden nevada

Karma: 6

Senior Member

Since you have 2 red holly pumps why not eliminate the tank selector valve and use a pump for each tank and run the fuel line up the rear of the engine when you disconnect the mechanical pump?

Roy Keen Minden,NV 76 X Glenbrook

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Re: Eliminating Vapor Lock [message #255077 is a reply to message #255070]

Fri, 11 July 2014 13:20

Jeff Marten

Messages: 199
Registered: August 2013

Karma: 1

Senior Member

I think if both pumps were running the main and AUX feeds simultaneously, I'd get too much line pressure for the seats to handle, and overfill the carb.

Could I run a single pump between the selector valve and carb? That way in either normal or AUX mode I'd only have a single pump running.

1985 Gulf Stream 34' Sun Stream 1964 Falcon 'Vert 1980 Bradley GTE 1999 Chevy Tahoe 2005 Saab 93 Aero 1987 Suzuki Intruder 1400 1978 Glastron/Carlson CV23

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Re: Eliminating Vapor Lock [message #255080 is a reply to message #254741]

Fri, 11 July 2014 14:11

kerry pinkerton

Messages: 2565
Registered: July 2012
Location: Harvest, Al

Karma: 15

Senior Member

I'm about to redo my fuel/vent system and go with two external pumps similar to what Ken Henderson describes on his photo album pages, replace body pads, and vent both tanks to the filler neck, etc.

Realizing the big flat gas tanks pick up a lot of road heat, I also wonder if engine compartment heat is a factor. To that end, I've been wondering is it would help to slide a piece of say 1/2 ID rubber hose OVER the steel line all the way to the carb. Also, we have this source of cool water in the engine compartment in the form of the AC condenser drain. What if that water was fed into this rubber hose to flow down the rubber line and drain out near the fuel pumps? As the hose heated up, I'd think there would be some evaporative cooling benefit.

Both these would be relatively easy to do but I'm not sure it's worth the effort???

Kerry Pinkerton - North Alabama Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L

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Re: Eliminating Vapor Lock [message #255081 is a reply to message #254741]

Fri, 11 July 2014 14:19

Chris Tyler

Messages: 458
Registered: September 2013
Location: Odessa FL

Karma: 7

Senior Member

Two pumps in paralell probably wont inrease the pressure. The red pumps are faily low pressure. Still, with a Qjet, it would be a good idea to run a regulator. Im a big fan of bypass regulators and a return line, but that may be getting complex.

Yes, there is a risk of an electric pump downstream flooding the crankcase if the diaphram ruptures. Ask me how I know...

A lot of OEMs used holley red pumps as boosters. If they failed, the mech pump would not pull theough them. [Changed a lot of those out to Carters, which seemed to hold up better running continiously.]
Mine is set up with a carter pump on a bypass loop, just turn it on to prime or when needed.

Those little cube pumps are also handy as a booster /prime pump for the genset

76 Glenbrook

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Re: Eliminating Vapor Lock [message #255084 is a reply to message #254741]

Fri, 11 July 2014 14:27

Chris Tyler

Messages: 458
Registered: September 2013
Location: Odessa FL

Karma: 7

Senior Member

DEI and some other companies make reflective heat sheiding for fuel lines that works well. I have tried insulating with fuel line before and found it didnt help

76 Glenbrook

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Re: Eliminating Vapor Lock [message #255091 is a reply to message #254741]

Fri, 11 July 2014 15:35

George Beckman

Messages: 1085
Registered: October 2008
Location: Colfax, CA

Karma: 11

Senior Member

Jeff Marten wrote on Tue, 08 July 2014 14:13

The Royale has a bit of vapor lock when the ambient temp is over ~85*. Once the ambient temp drops into the 70's there is no issue. A PO has installed an insulated fuel line from the fuel pump to carb. I'm contemplating installing a bypass from the carb back to the tank to keep the fuel moving.
However, I just saw some info on Bdub's pages about vapor lock and using the Carter kit. Assume this has two one-way valves to recirc/bypass the fuel.
How well do these fare against vapor lock?
Alternatively, I have a couple good spare Holley red pumps, and could install one without the recirc/bypass. Any real difference in functionality?
Not looking to do anything more intrusive or costly at this time; too many higher-priority projects this year.

A couple of things I think about with vapor lock are pressure and heat. Modern vehicles have high pressure systems with pumps in the tank. Why? Because like water, gas boils/vaporizes at lower temperatures as the pressure drops. (Pressure cooker vs potatoes that don't cook at 10,000 feet.) Why pumps in the tank? It is unlikely the gas will boil in the tanks to the point that a submerged pump will take in air bubbles. These measures were taken at least in part to eliminate vapor-lock with new fuels.

Given the above, the reverse is true. Reducing pressure is not good. Water and gas boil sooner when pressure is relieved. In our systems pressure is relieved when pumps create suction trying to draw gas from the tanks.

So, if we are to fix vapor-lock I believe it must happen as close to the tank as possible. (If we don't put pumps in the tanks and I have not done that)

I hear tales that some have drilled a hole in the gas cap. I would think this is counterproductive, My tanks tend to have pressure in them when I let my cap loose to fill. That pressure in the tank may help a tiny bit to keep gas from boiling; perhaps proven by the gasoline baths several of us have taken before we learned to open a GMC gas cap slowly.

As far as the recirculation, when I converted my first GMC to fuel injection the recirculating gas built heat and therefore pressure in the tanks so fast the gas gauge would actually go down. I could fill the tanks and within 1/2 hour I would have 3/4 of a tank of gas. If I stopped and slowly and carefully let the pressure off, I could get back in and have a full tank on the gauge. The tanks were expanding, top to bottom, that much. When I bought our current coach I moved the EFI to the new coach and the heating has not been a problem. The only thing I can think of is changing from the orange hose supplied at the time by Howell to Gates hoses.

So, recirculation may help the heat at the carb but the heat is going to the tank and heating fuel. If the fuel is being sucked very far or at all for that matter, there is a low pressure point for vapor-lock... the warmer the fuel is.

While I agree modern fuels boil sooner I am (I know, and unpopular position) not convinced that we can blame it all on ethanol. After lead was removed from gasoline it had to be replaced with something to tame the fuel. Ethanol octane rating of 113 raises the octane. I use ethanol gas 90% of the time because I live in California. When in the midwest I suppose I occasionally get "real gas" but it has been laced with something. They have to get the octane up somehow. I am convinced that the summer of 2012 ethanol was being removed from gas because of the drought in the midwest. My rig was suddenly pinging with the same advance tables that had not pinged for years. I read about MTBE, ETBE, isooctane and toluene being used to raise octane. I don't know what they are; I suppose Emery will have to explain it to me some time. I just as soon have ethanol. I know what ethanol is.

Just my two cents.

'74 Eleganza, SE, Howell + EBL
Best Wishes,
George

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Re: [GMCnet] Eliminating Vapor Lock [message #255095 is a reply to message #255045]

Fri, 11 July 2014 17:00

Ken Henderson

Messages: 8726
Registered: March 2004
Location: Americus, GA

Karma: 9

Senior Member

Jeff,

Just an expression of personal experience and preference: I've run one or
two electric fuel pumps on my GMC for all but a few early months of my 15
years' ownership. The only one I ever had ANY trouble with was the RED
Holley that, literally, melted down about 8 years ago: The tar was
dripping from it when I looked under the coach at Orange Park, FL to see
why it wasn't working.

Mine may have been the ONLY one of them to every do that -- but it won't
happen again with me.

Ken H.

On Fri, Jul 11, 2014 at 9:16 AM, Jeff Marten wrote:

> OK, I'm going to work on installing one of my Holley red pumps tomorrow.
> Anyone have pics of where the electric pump is generally tied in to the
> AUX
> fuel line?
>
> Alternatively, I'm considering just pulling the mech pump and installing
> the Holley in the main fuel line as my only pump. From what I remember
> reading about the Holley, it has an internal spring-loaded bypass, so no
> need for all the one-way valves, tees, bypass loop, and multiple leak point
> potentials the Carter setup has.
>
> Anyone else running just an electric pump setup with a carb?
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach

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Re: [GMCnet] Eliminating Vapor Lock [message #255113 is a reply to message #255095]

Fri, 11 July 2014 20:27

Jeff Marten

Messages: 199
Registered: August 2013

Karma: 1

Senior Member

The Holley (prob most rotary vane electrics as well) will burn up quickly if they have to pull fuel even a little. They're really only effective for a gravity feed system where they can push the fuel. I think I'll pick up a new solenoid drive pump instead of using the Holley; I'll save it for use on my Falcon 'vert instead.

> From: hend4800@bellsouth.net
> Date: Fri, 11 Jul 2014 18:00:12 -0400
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] Eliminating Vapor Lock
>
> Jeff,
>
> Just an expression of personal experience and preference: I've run one or
> two electric fuel pumps on my GMC for all but a few early months of my 15
> years' ownership. The only one I ever had ANY trouble with was the RED
> Holley that, literally, melted down about 8 years ago: The tar was
> dripping from it when I looked under the coach at Orange Park, FL to see
> why it wasn't working.
>
> Mine may have been the ONLY one of them to every do that -- but it won't
> happen again with me.
>
> Ken H.
>
>
> On Fri, Jul 11, 2014 at 9:16 AM, Jeff Marten wrote:
>
>> OK, I'm going to work on installing one of my Holley red pumps tomorrow.
>> Anyone have pics of where the electric pump is generally tied in to the
>> AUX
>> fuel line?
>>
>> Alternatively, I'm considering just pulling the mech pump and installing
>> the Holley in the main fuel line as my only pump. From what I remember
>> reading about the Holley, it has an internal spring-loaded bypass, so no
>> need for all the one-way valves, tees, bypass loop, and multiple leak point
>> potentials the Carter setup has.
>>
>> Anyone else running just an electric pump setup with a carb?
>> --
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

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1985 Gulf Stream 34' Sun Stream 1964 Falcon 'Vert 1980 Bradley GTE 1999 Chevy Tahoe 2005 Saab 93 Aero 1987 Suzuki Intruder 1400 1978 Glastron/Carlson CV23

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Re: Eliminating Vapor Lock [message #255133 is a reply to message #255077]

Sat, 12 July 2014 01:06

roy1

Messages: 2126
Registered: July 2004
Location: Minden nevada

Karma: 6

Senior Member

Jeff Marten wrote on Fri, 11 July 2014 11:20

I think if both pumps were running the main and AUX feeds simultaneously, I'd get too much line pressure for the seats to handle, and overfill the carb.

Could I run a single pump between the selector valve and carb? That way in either normal or AUX mode I'd only have a single pump running.

I wouldn't run both pumps together . Just run the main pump in that position and the auxiliary pump in auxiliary position this will make the selector valve unnecessary which is likely worn out if it is old. You won't need the mechanical pump any longer and you will have a second pump already plumbed in if you have a pump failure. I also had a problem with a holly pump in the distant past. I used to have a carter electric pump between the aux tank and the selector that powered on when in aux position .I have since changed to 2 electric pumps and no selector valve.

Roy Keen Minden,NV 76 X Glenbrook

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Re: Eliminating Vapor Lock [message #255170 is a reply to message #255077]

Sat, 12 July 2014 13:31

Bob de Kruyff

Messages: 4260
Registered: January 2004
Location: Chandler, AZ

Karma: 1

Senior Member

Jeff Marten wrote on Fri, 11 July 2014 12:20

I think if both pumps were running the main and AUX feeds simultaneously, I'd get too much line pressure for the seats to handle, and overfill the carb.

Could I run a single pump between the selector valve and carb? That way in either normal or AUX mode I'd only have a single pump running.

I'm not aguing with you plumbing thoughts but two pumps running at the same time will not create more pressure--just double the volume.

Bob de Kruyff
78 Eleganza
Chandler, AZ

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Re: Eliminating Vapor Lock [message #255171 is a reply to message #255080]

Sat, 12 July 2014 13:38

Bob de Kruyff

Messages: 4260
Registered: January 2004
Location: Chandler, AZ

Karma: 1

Senior Member

Kerry Pinkerton wrote on Fri, 11 July 2014 13:11

I'm about to redo my fuel/vent system and go with two external pumps similar to what Ken Henderson describes on his photo album pages, replace body pads, and vent both tanks to the filler neck, etc.

Realizing the big flat gas tanks pick up a lot of road heat, I also wonder if engine compartment heat is a factor. To that end, I've been wondering is it would help to slide a piece of say 1/2 ID rubber hose OVER the steel line all the way to the carb. Also, we have this source of cool water in the engine compartment in the form of the AC condenser drain. What if that water was fed into this rubber hose to flow down the rubber line and drain out near the fuel pumps? As the hose heated up, I'd think there would be some evaporative cooling benefit.

Both these would be relatively easy to do but I'm not sure it's worth the effort???

There is insulating wrap and conduit available for the line from the pump to the carburetor at most auto parts stores. As far as the AC condensate, I doubt there is enough of it and by the time you get it to the carb line, it may be as hot as the fuel. A few months ago we had a discussion about fuel coolers that tapped into the freon side of the AC system.

Bob de Kruyff
78 Eleganza
Chandler, AZ

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Re: Eliminating Vapor Lock [message #255172 is a reply to message #255091]

Sat, 12 July 2014 13:49

Bob de Kruyff

Messages: 4260
Registered: January 2004
Location: Chandler, AZ

Karma: 1

Senior Member

""While I agree modern fuels boil sooner I am (I know, and unpopular position) not convinced that we can blame it all on ethanol. After lead was removed from gasoline it had to be replaced with something to tame the fuel. Ethanol octane rating of 113 raises the octane. I use ethanol gas 90% of the time because I live in California. When in the midwest I suppose I occasionally get "real gas" but it has been laced with something. They have to get the octane up somehow. I am convinced that the summer of 2012 ethanol was being removed from gas because of the drought in the midwest. My rig was suddenly pinging with the same advance tables that had not pinged for years. I read about MTBE, ETBE, isooctane and toluene being used to raise octane. I don't know what they are; I suppose Emery will have to explain it to me some time. I just as soon have ethanol. I know what ethanol is.

Just my two cents.
""

George, you make a lot of good points and I'll only talk about a couple of them. New FI systems are non recirculating because of the heat build up as you mention. I also think most people on the net blame Ethanol for their fuel delivery issues including vapor lock. I think ethanol is a minor contributor but that neglected or otherwise flawed basic fuel systems are primarily to blame. I travel in the southwest at temperatures well over 100F and have only an occasional burp if the elevation reaches 5K or more on an incline. I do have a booster pump that I switch on for about 30 seconds till I get over the hill.

Bob de Kruyff
78 Eleganza
Chandler, AZ

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Re: [GMCnet] Eliminating Vapor Lock [message #255985 is a reply to message #255172]

Sun, 20 July 2014 23:18

Jeff Marten

Messages: 199
Registered: August 2013

Karma: 1

Senior Member

Got the new electric fuel pump installed today. A PO had installed an insulated line from the carb to mech pump at some point. I used a flare union to convert the insulated hose to a hose barb. I insulated the new 3/8" fuel line using three, 3ft lengths of 3/4" heat shield tubing (sold in 3ft sections). I used a short piece of heat shield tape to bridge the seams, adding a pair of zip-ties to make sure it stays in place. I routed the fuel line to the back of the engine, down and around to the inside of the frame rail. Heat shield tubing covers the hose from the end of the insulated line to the pump. Pump is a generic solenoid-drive installed about a foot in front of the selector valve. Mech pump is now just a placeholder, like a zero. LOL I left the original fuel lines in place.
I found a triple vac port at the front of the intake with two open ports. Sealed those off with a short length of vac hose.
She runs very well, and seems to be smoother; not sure if it's due to plugging those ports or more consistent fuel delivery.

And now I know why everyone seems to install an electric pump only in the AUX line - they're too dang lazy (or smart) to run a power feed all the way to the glove box! LOL I was very glad to see there was a blade available marked IGN.

Hopefully I'll have an opportunity next weekend to see if this has eliminated the vapor lock.

> Date: Sat, 12 Jul 2014 12:49:47 -0600
> To: gmclist@temp.gmcnet.org
> From: NEXT2POOL@gmail.COM
> Subject: Re: [GMCnet] Eliminating Vapor Lock
>
> ""While I agree modern fuels boil sooner I am (I know, and unpopular position) not convinced that we can blame it all on ethanol. After lead was
> removed from gasoline it had to be replaced with something to tame the fuel. Ethanol octane rating of 113 raises the octane. I use ethanol gas 90% of
> the time because I live in California. When in the midwest I suppose I occasionally get "real gas" but it has been laced with something. They have to
> get the octane up somehow. I am convinced that the summer of 2012 ethanol was being removed from gas because of the drought in the midwest. My rig was
> suddenly pinging with the same advance tables that had not pinged for years. I read about MTBE, ETBE, isooctane and toluene being used to raise
> octane. I don't know what they are; I suppose Emery will have to explain it to me some time. I just as soon have ethanol. I know what ethanol is.
>
> Just my two cents.
> ""
>
> George, you make a lot of good points and I'll only talk about a couple of them. New FI systems are non recirculating because of the heat build up as
> you mention. I also think most people on the net blame Ethanol for their fuel delivery issues including vapor lock. I think ethanol is a minor
> contributor but that neglected or otherwise flawed basic fuel systems are primarily to blame. I travel in the southwest at temperatures well over 100F
> and have only an occasional burp if the elevation reaches 5K or more on an incline. I do have a booster pump that I switch on for about 30 seconds
> till I get over the hill.
> --
> Bob de Kruyff
> 78 Eleganza
> Chandler, AZ
> _______________________________________________
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> Unsubscribe or Change List Options:
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1985 Gulf Stream 34' Sun Stream 1964 Falcon 'Vert 1980 Bradley GTE 1999 Chevy Tahoe 2005 Saab 93 Aero 1987 Suzuki Intruder 1400 1978 Glastron/Carlson CV23

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Re: Eliminating Vapor Lock [message #256007 is a reply to message #254741]

Mon, 21 July 2014 11:50

Chris Tyler

Messages: 458
Registered: September 2013
Location: Odessa FL

Karma: 7

Senior Member

"As far as the recirculation, when I converted my first GMC to fuel injection the recirculating gas built heat and therefore pressure in the tanks so fast the gas gauge would actually go down. I could fill the tanks and within 1/2 hour I would have 3/4 of a tank of gas. If I stopped and slowly and carefully let the pressure off, I could get back in and have a full tank on the gauge. The tanks were expanding, top to bottom, that much. When I bought our current coach I moved the EFI to the new coach and the heating has not been a problem. The only thing I can think of is changing from the orange hose supplied at the time by Howell to Gates hoses.

So, recirculation may help the heat at the carb but the heat is going to the tank and heating fuel. If the fuel is being sucked very far or at all for that matter, there is a low pressure point for vapor-lock... the warmer the fuel is."

Thats interesting. Hasn't been my experience with recirulating systems but then I wasn't dealing with those huge tanks that werent designed to contain pressure either.

I kept the mechanical fuel pump on 2 vehicles as a backuo, ran a loop to keep some fuel circulating to preserve it. Came in handy once.

76 Glenbrook

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