No Ported Vacuum

Hi All,

I am not getting any ported vacuum going to my EGR valve. I checked the vac
at the connection that is on the top of the Carter BBD - the one on the
engine side of the carb and there is no vacuum at any RPM. Anyone have any
ideas why?

Thanks in advance,
Steve

Because the vacuum at that port depends on load? Have you triple-checked to
make sure that it is the correct port?

Earle

"steve" > wrote in message
...
> Hi All,
>
> I am not getting any ported vacuum going to my EGR valve. I checked the
vac
> at the connection that is on the top of the Carter BBD - the one on the
> engine side of the carb and there is no vacuum at any RPM. Anyone have
any
> ideas why?
>
> Thanks in advance,
> Steve
>
>
>

Then I would guess someone put the carb's base gaskets on wrong. There
are channels in them that direct the vacuum flow.

Do you have manifold vacuum at any ports?

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Aug./05 http://www.imagestation.com/album/in...?id=2120343242
(More Off Road album links at bottom of the view page)

steve wrote:
>
> Hi All,
>
> I am not getting any ported vacuum going to my EGR valve. I checked the vac
> at the connection that is on the top of the Carter BBD - the one on the
> engine side of the carb and there is no vacuum at any RPM. Anyone have any
> ideas why?
>
> Thanks in advance,
> Steve

One other thing, the hole could just be plugged. Maybe try spraying
some carb cleaner into the nipple to see if it comes out on the inside.

Mike

Mike Romain wrote:
>
> Then I would guess someone put the carb's base gaskets on wrong. There
> are channels in them that direct the vacuum flow.
>
> Do you have manifold vacuum at any ports?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
> Canadian Off Road Trips Photos: Non members can still view!
> Aug./05 http://www.imagestation.com/album/in...?id=2120343242
> (More Off Road album links at bottom of the view page)
>
> steve wrote:
> >
> > Hi All,
> >
> > I am not getting any ported vacuum going to my EGR valve. I checked the vac
> > at the connection that is on the top of the Carter BBD - the one on the
> > engine side of the carb and there is no vacuum at any RPM. Anyone have any
> > ideas why?
> >
> > Thanks in advance,
> > Steve

Thanks for all the advice...but, I have checked if the port is clear
(sprayed cleaner through it), the carb gasget has never been removed or
replaced, and I do have vacuum at the manifold ports. When you say the
ported vacuum depends on load, should I still get some vacuum if I just rev
the engine?

"steve" > wrote in message
...
> Hi All,
>
> I am not getting any ported vacuum going to my EGR valve. I checked the
> vac at the connection that is on the top of the Carter BBD - the one on
> the engine side of the carb and there is no vacuum at any RPM. Anyone
> have any ideas why?
>
> Thanks in advance,
> Steve
>

If I remember my emissions control theory right, the EGR is supposed to work
at part throttle, not full load, when the mixture, caused by the other
emissions controls, is too lean. You inject exhaust gas into the too-lean
mixture, and it makes it less lean, without making it richer. This lowers
the combustion temperature, and theoretically oxides of nitrogen. If you
think about it, this means that your EGR isn't designed to kick in when you
are idling, or playing with the throttle in your garage. You have to be
going down the road, with a certain amount of air flowing, burning a certain
amount of fuel, to get appreciable vacuum at that port.

This means also that your state emissions compliance program isn't going to
succeed in testing the operation of your EGR valve, unless they have a
chassis dynamometer, and maybe not even then. I had a car in Washington
State pass with flying colors, even though they put the car on the
dynamometer and ran it at 30 mph, with the under-vehicle part of the EGR
plumbing, completely rotted through and brazed shut. Why do you want the
EGR working? It isn't going to do anything, except plug the filter, rot the
plumbing, and eventually stop working by itself. The theory is somewhat
plausible, but the effect on emissions is negligible at best.

I don't really know why you are not getting vacuum at that port, but I
suspect that you may not, with the vehicle in the garage. Are you
absolutely sure it is the correct port for the EGR?

Earle

"steve" > wrote in message
...
> Thanks for all the advice...but, I have checked if the port is clear
> (sprayed cleaner through it), the carb gasget has never been removed or
> replaced, and I do have vacuum at the manifold ports. When you say the
> ported vacuum depends on load, should I still get some vacuum if I just
rev
> the engine?
>
> "steve" > wrote in message
> ...
> > Hi All,
> >
> > I am not getting any ported vacuum going to my EGR valve. I checked the
> > vac at the connection that is on the top of the Carter BBD - the one on
> > the engine side of the carb and there is no vacuum at any RPM. Anyone
> > have any ideas why?
> >
> > Thanks in advance,
> > Steve
> >
>
>
>

I have the top valve cover side nipple on my BBD hooked via a T-fitting
to my distributor and CTO valve. The CTO valve then powers the air
filter switch for the EGR valve. The EGR valve has a vacuum delay disk
in the line. If this disk is backward, the EGR will not see vacuum.

When I am sitting at an idle and I give the engine a shot of gas, I can
see and hear my distributor advance physically move in perfect time to
the gas pedal.

When I punch it, I have full advance.

I don't understand how there can be no ported vacuum if the nipple
sprays clear with cleaner.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Aug./05 http://www.imagestation.com/album/in...?id=2120343242
(More Off Road album links at bottom of the view page)

steve wrote:
>
> Thanks for all the advice...but, I have checked if the port is clear
> (sprayed cleaner through it), the carb gasget has never been removed or
> replaced, and I do have vacuum at the manifold ports. When you say the
> ported vacuum depends on load, should I still get some vacuum if I just rev
> the engine?
>
> "steve" > wrote in message
> ...
> > Hi All,
> >
> > I am not getting any ported vacuum going to my EGR valve. I checked the
> > vac at the connection that is on the top of the Carter BBD - the one on
> > the engine side of the carb and there is no vacuum at any RPM. Anyone
> > have any ideas why?
> >
> > Thanks in advance,
> > Steve
> >

Hi Steve,
I don't know how the AMC six is set up, other than the diagram at:
http://home.sprynet.com/~dale02/vac-egr.htm On my Ford there are many
valves the vacuum goes through on the way toe Exhaust Gases Recycling
valve. Remember you don't want it wide open pouring exhaust into the
intake manifold at idle. So on a Ford one of the control valves is
operate by the venturi vacuum port that only has vacuum with the high
velocity of air passing through the venturi, which looks like this on a
Ford: http://www.billhughes.com/decelValve.jpg
God Bless America, Bill O|||||||O


steve wrote:
>
> Thanks for all the advice...but, I have checked if the port is clear
> (sprayed cleaner through it), the carb gasget has never been removed or
> replaced, and I do have vacuum at the manifold ports. When you say the
> ported vacuum depends on load, should I still get some vacuum if I just rev
> the engine?
>
> "steve" > wrote in message
> ...
> > Hi All,
> >
> > I am not getting any ported vacuum going to my EGR valve. I checked the
> > vac at the connection that is on the top of the Carter BBD - the one on
> > the engine side of the carb and there is no vacuum at any RPM. Anyone
> > have any ideas why?
> >
> > Thanks in advance,
> > Steve
> >

steve alleged...
> Thanks for all the advice...but, I have checked if the port is clear
> (sprayed cleaner through it), the carb gasget has never been removed or
> replaced, and I do have vacuum at the manifold ports. When you say the
> ported vacuum depends on load, should I still get some vacuum if I just rev
> the engine?
>
> "steve" > wrote in message
> ...
> > Hi All,
> >
> > I am not getting any ported vacuum going to my EGR valve. I checked the
> > vac at the connection that is on the top of the Carter BBD - the one on
> > the engine side of the carb and there is no vacuum at any RPM. Anyone
> > have any ideas why?
> >
> > Thanks in advance,
> > Steve
> >
>
>
>

If you briefly crack the throttle maybe a quarter open, you should
definitely see vacuum at the port. You should be able to feel it with your
finger, and it's enough to pull the EGR open slightly.
Assuming you find that you do indeed have ported vacuum, the EGR should
still not work if the engine is not warmed up. Check this diagram:
http://home.sprynet.com/~dale02/vac-egr.htm
Check for vacuum at the carb port, in/out of the CTO, and in/out of the TVS
in the air cleaner.
Check the canister purge line for a massive leak.


--

Dale Beckett

The mid 70's Dodge system was similar. Vacuum only at raised engine speeds,
none at idle.

--
(remove SPAM)
2002 Jeep WJ 4 Liter Automatic
Sharing is why we are all here....... or should be.
..
"L.W. ("ßill") Hughes III" > wrote in message
...
> Hi Steve,
> I don't know how the AMC six is set up, other than the diagram at:
> http://home.sprynet.com/~dale02/vac-egr.htm On my Ford there are many
> valves the vacuum goes through on the way toe Exhaust Gases Recycling
> valve. Remember you don't want it wide open pouring exhaust into the
> intake manifold at idle. So on a Ford one of the control valves is
> operate by the venturi vacuum port that only has vacuum with the high
> velocity of air passing through the venturi, which looks like this on a
> Ford: http://www.billhughes.com/decelValve.jpg
> God Bless America, Bill O|||||||O
>
>
> steve wrote:
>>
>> Thanks for all the advice...but, I have checked if the port is clear
>> (sprayed cleaner through it), the carb gasget has never been removed or
>> replaced, and I do have vacuum at the manifold ports. When you say the
>> ported vacuum depends on load, should I still get some vacuum if I just
>> rev
>> the engine?
>>
>> "steve" > wrote in message
>> ...
>> > Hi All,
>> >
>> > I am not getting any ported vacuum going to my EGR valve. I checked
>> > the
>> > vac at the connection that is on the top of the Carter BBD - the one on
>> > the engine side of the carb and there is no vacuum at any RPM. Anyone
>> > have any ideas why?
>> >
>> > Thanks in advance,
>> > Steve
>> >