Fitech question-line from canisters

S

scott nutter1

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Jan 5, 2015
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Does the Fitech throttle body have a port for the return line from the canisters? Or is that line not used with the Fitech?
I would think it's not used because of the higher pressure in the main fuel lines.
Thanks, Scott.
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi.
Houston, Texas
 
Forum seems to have lost my response, so I'll re-type it.

By "Canister" I'm guessing you are referring to the charcoal canister(s) behind the front passenger tire. It collects gasoline vapours that would
otherwise be lost to the atmosphere. The outlet from the canister is generally connected ported vacuum on the carb or throttle body.

I looked on the FiTech site, but I could not find a manual or any mention of vacuum line connections. There must be something on it otherwise I can't
see their system passing any kind of pollution control. You want to capture and burn these gases because it's energy you paid for!

The EBL system operates an evaporative purge valve that connects directly to the intake manifold. I got my valve solenoid from a Jeep.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
Hubler 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
> Does the Fitech throttle body have a port for the return line from the canisters? Or is that line not used with the Fitech?
> I would think it's not used because of the higher pressure in the main fuel lines.
> Thanks, Scott.

I have struggled with this issue for the FiTech. There really is not any discussion about our type of canister (I'm guessing you are talking about
the vapor canister on the passenger side). The larger vacuum ports on the FiTech are Manifold vacuum. I have tried using those and while it worked I
was concerned with the idle integrity. I have been hooking the canister to the ported vacuum port on the back of the FiTech. It is a smaller port so
I had to use a reducing connector. Early applications like ours, the canister normally is hooked to a controlled port (ported) on the carburetor or
the Rochester Throttle Body specifically designed for canister purging. Later, GM added temp control using the TVS then vacuum control on the canister
to determine when to start a purge cycle. Our application is fairly simple - hook it to ported vacuum. For Fuel Injected systems, the ECM allows for
this vacuum leak or the self learning will compensate for it. Not eloquent but seems to work.

--
Randy & Margie
'77 Eleganza II '403'
Battlefield, MO
 
I'd suggest connecting a canister to a ported source, not direct manifold vacuum. Vapor amount can overwhelm the adaptive control at idle and cause
surges and stalls. Ideally any EFI system will operate a purge valve to coordinate canister purge vapor with fuel delivery. Absent this a ported
source will at least keep the vapor out of the idle and decel regions. You will still have to contend with the EFI adaptation swinging considerably
between the vapor levels of a full or empty canister.
--
Chris Geils - Twin Cities
1978 26' Kingsley w/ very few mods; Headers, Progressive Dynamics 9040, aux trans cooler, one repaint in stock colors, R134a, Al rad, 50k mi
 
Sorry, I should of been more exact. It is the vapor canister up on the passengers side.
Is it even needed? if I blocked the line from the canister it just vents to the atmosphere, right?
Is there anywhere else that line could be vented to? To the fuel fill hose?
If it has to go back to the engine area, I would think it would be better to go to the throttle body vs the block?

I guess I need to review the canister Philosophy to get a better understanding of what it does...........
Scott
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi.
Houston, Texas
 
It absorbs liquid fuel, and allows vapors to exit through the canister hose
(s) to be consumed by the engine. The reason that it goes into the inlet
tract at the carb is that all cylinders get an equal (more or less) dose.
If you vent it into the front or rear of the manifold, then the nearest
cylinders MIGHT get a richer mixture than the others. Throttle body is the
best place to attach the hose. Above or below the throttle plates is a
subject for discussion. I have some ideas based upon my experience and
training, others may have different opinions.
In any case, don't vent it to the atmosphere. We all agree that is
not the right thing to do.
Jim Hupy
Salem, Or

> Sorry, I should of been more exact. It is the vapor canister up on the
> passengers side.
> Is it even needed? if I blocked the line from the canister it just vents
> to the atmosphere, right?
> Is there anywhere else that line could be vented to? To the fuel fill hose?
> If it has to go back to the engine area, I would think it would be better
> to go to the throttle body vs the block?
>
> I guess I need to review the canister Philosophy to get a better
> understanding of what it does...........
> Scott
> --
> Scott Nutter
> 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final
> drive, Quad bags, tankless water heater, everything Lenzi.
> Houston, Texas
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
> It absorbs liquid fuel, and allows vapors to exit through the canister hose (s) to be consumed by the engine. The reason that it goes into the
> inlet tract at the carb is that all cylinders get an equal (more or less) dose.
> If you vent it into the front or rear of the manifold, then the nearest cylinders MIGHT get a richer mixture than the others. Throttle body is
> the
> best place to attach the hose. Above or below the throttle plates is a subject for discussion. I have some ideas based upon my experience and
> training, others may have different opinions.
> In any case, don't vent it to the atmosphere. We all agree that is not the right thing to do.
> Jim Hupy
> Salem, Or

Jim,

We seldom have any variation, but I have some experience that is uncommon.

The (carbon, charcoal) canister can only handle fuel vapor. That is why it is such a problem when that little 5h1t thing in wheel well screws up
(again) it can be such a PITA. I ended up having to repack the two of mine (CARP code) twice. This last time I cut it back to just one canister as I
will never register the coach in California.

Technical Stuff:
When we did initial calibration of an engine, part of that study was "Purge Tolerance". This was to find out what part of the engine's operation map
(not MAP) it was best able to handle and/or control the additional fuel or air that the purging of the canister would put in the system. In old
carburetor engines, it has to be a ported intake. The top of the canister had a valve system that is most like a PVC valve in that it restricted flow
at high vacuum (low MAP) to prevent overloading the combustion with the purge. Neither those valves or the carbon packing like liquid fuel.

This is now, like every other blasted thing, in many vehicles is controlled by the ECM and an electric valve.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
Matt, that is why I did not get too specific with my answers ( evasive).
Those emission devices of the 70's were fairly imprecise. (Grin) When the
canisters did get a big slug of liquid fuel, bad running most likely was
the result, to say nothing of the emissions. When I think of those exhaust
manifolds with rusted out AIR tubes, and stuck and carboned up EGR valves,
burned out crossover passages, and the rest of that stuff, it makes me very
glad I don't have to work on that stuff any more. Computers changed all
that stuff for the better, I think. But, canisters are a good thing for the
environment, and we should be able to make them work.
They really don't work well with alcohol blended fuel that
deteriorates the hoses and plastic parts not specifically designed for it
like the liquid/vapor separator and those valves in the top of the canister
that you talked about.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> > It absorbs liquid fuel, and allows vapors to exit through the canister
> hose (s) to be consumed by the engine. The reason that it goes into the
> > inlet tract at the carb is that all cylinders get an equal (more or
> less) dose.
> > If you vent it into the front or rear of the manifold, then the nearest
> cylinders MIGHT get a richer mixture than the others. Throttle body is
> > the
> > best place to attach the hose. Above or below the throttle plates is a
> subject for discussion. I have some ideas based upon my experience and
> > training, others may have different opinions.
> > In any case, don't vent it to the atmosphere. We all agree that is
> not the right thing to do.
> > Jim Hupy
> > Salem, Or
>
> Jim,
>
> We seldom have any variation, but I have some experience that is uncommon.
>
> The (carbon, charcoal) canister can only handle fuel vapor. That is why
> it is such a problem when that little 5h1t thing in wheel well screws up
> (again) it can be such a PITA. I ended up having to repack the two of
> mine (CARP code) twice. This last time I cut it back to just one canister
> as I
> will never register the coach in California.
>
> Technical Stuff:
> When we did initial calibration of an engine, part of that study was
> "Purge Tolerance". This was to find out what part of the engine's
> operation map
> (not MAP) it was best able to handle and/or control the additional fuel or
> air that the purging of the canister would put in the system. In old
> carburetor engines, it has to be a ported intake. The top of the canister
> had a valve system that is most like a PVC valve in that it restricted flow
> at high vacuum (low MAP) to prevent overloading the combustion with the
> purge. Neither those valves or the carbon packing like liquid fuel.
>
> This is now, like every other blasted thing, in many vehicles is
> controlled by the ECM and an electric valve.
>
> Matt
> --
> Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan
> OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
I ran mine disconnected and vented to the outside air for several years. Every once and a while, while parked someone would say I smell gas leaking
near the front of your coach. One day I walked by it and smelled it myself so I chased down the smell. I took the time to reconnect it where it
belonged on the front of the carb. No more smell.

The reason my was disconnected was after my engine fire with everything I was replacing I failed to make a new hose and hook it up. I always wondered
what that extra port on the front of the carb was for.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
> I ran mine disconnected and vented to the outside air for several years. Every once and a while, while parked someone would say I smell gas
> leaking near the front of your coach. One day I walked by it and smelled it myself so I chased down the smell. I took the time to reconnect it
> where it belonged on the front of the carb. No more smell.
>
> The reason my was disconnected was after my engine fire with everything I was replacing I failed to make a new hose and hook it up. I always
> wondered what that extra port on the front of the carb was for.

All of my Fitech ports are used up by other vacuum demanding things, so I drilled a hole in the bottom of the airfilter on the "clean" side of the
element and put on a port reasoning that there would be a drop in pressure between the clean and dirty sid of the element (however minor) and would
allow fumes from the cannister to flow. Seems to have worked. Just what I did,
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
> > I ran mine disconnected and vented to the outside air for several years. Every once and a while, while parked someone would say I smell gas
> > leaking near the front of your coach. One day I walked by it and smelled it myself so I chased down the smell. I took the time to reconnect it
> > where it belonged on the front of the carb. No more smell.
> >
> > The reason my was disconnected was after my engine fire with everything I was replacing I failed to make a new hose and hook it up. I always
> > wondered what that extra port on the front of the carb was for.
>
>
> All of my Fitech ports are used up by other vacuum demanding things, so I drilled a hole in the bottom of the airfilter on the "clean" side of
> the element and put in a port reasoning that there would be a drop in pressure between the clean and dirty sid of the element (however minor) and
> would allow fumes from the cannister to flow. Seems to have worked. Just what I did,


That is a great idea. Low draw at idle and higher draw at faster speeds.

Also the dirtier the air filter is the more draw you will get on the canister.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
> That won't create enough draw to regenerate the carbon media.

What are the symptoms if not enough draw. Just wondering what to watch for.

--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
> > That won't create enough draw to regenerate the carbon media.
>
> What are the symptoms if not enough draw. Just wondering what to watch for.

John is correct, that slight depression won't pull significant fuel out of the canister. The canister will continue to load every day just a little
bit due to the daily swings in ambient temp unless you are lucky enough to have climate controlled storage. These canisters can carry about 100 grams
of fuel, and once saturated will just puke any additional fuel vapor directly out the vent posing a minor fire hazard. This is particularly true in
the spring; first warm day with winter (high rvp) fuel and the tanks will generate a lot of vapor. The only solution is to run the purge line to a
vacuum source (or vent the tanks to atmosphere, defeating the emission control and losing unburned HC to the environment).
All EFI engines should have a purge metering valve, as Matt said. There can be enough vapor in the canister to overwhelm the closed loop control on a
hot day.
--
Chris Geils - Twin Cities
1978 26' Kingsley w/ very few mods; Headers, Progressive Dynamics 9040, aux trans cooler, one repaint in stock colors, R134a, Al rad, 50k mi
 
Been watching this discussion and checked my fitech and saw that my ecc hose was on manifold vacumn, could explain some weird idle problems after fill
ups. Only problem is that the only ported vacuum port is for the distributor, so if I was to adapt the hose down with a tee and hook it up wouldn't my
vacuum all leak off to the ecc and there would be none for the spark advance? Anyone with experience with this?

Skip Hartline
 
That is the huge advantages of the Howell system vs FiTech. Howell with EBL
has no need for vacuum advance or mechanical advance either. You can either
use the Holley or GM throttle bodies, but both are 2 throat. Sure would be
nice to have a 4 throat throttle body, a spread bore that fits the Olds
intake manifold. 3D printer anyone? Guy can dream.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Been watching this discussion and checked my fitech and saw that my ecc
> hose was on manifold vacumn, could explain some weird idle problems after
> fill
> ups. Only problem is that the only ported vacuum port is for the
> distributor, so if I was to adapt the hose down with a tee and hook it up
> wouldn't my
> vacuum all leak off to the ecc and there would be none for the spark
> advance? Anyone with experience with this?
>
> Skip Hartline
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Jim,
There is a 4 barrel thhrottle body by Hollly.
The 2 barrel unit has large throttle bores so you really donnot gain much
at low end.
The Howell based EBL unit performs very well as it has a very good timing
curve built in and it does not require any program modification..

> That is the huge advantages of the Howell system vs FiTech. Howell with EBL
> has no need for vacuum advance or mechanical advance either. You can either
> use the Holley or GM throttle bodies, but both are 2 throat. Sure would be
> nice to have a 4 throat throttle body, a spread bore that fits the Olds
> intake manifold. 3D printer anyone? Guy can dream.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>

>
> > Been watching this discussion and checked my fitech and saw that my ecc
> > hose was on manifold vacumn, could explain some weird idle problems after
> > fill
> > ups. Only problem is that the only ported vacuum port is for the
> > distributor, so if I was to adapt the hose down with a tee and hook it up
> > wouldn't my
> > vacuum all leak off to the ecc and there would be none for the spark
> > advance? Anyone with experience with this?
> >
> > Skip Hartline
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
G'day,

The Blue Streak has a Holly Commander EFI and it has a four barrel throttle body. As I understand it the technology is out dated at
this point in time.

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Jim Kanomata
Sent: Monday, February 26, 2018 1:42 PM
To: gmclist
Subject: Re: [GMCnet] Fitech question-line from canisters

Jim,
There is a 4 barrel thhrottle body by Hollly.
The 2 barrel unit has large throttle bores so you really donnot gain much at low end.
The Howell based EBL unit performs very well as it has a very good timing curve built in and it does not require any program
modification..

Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
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