worse mileage AFTER carb rebuild...

hey all - i'll try and keep it short. i just recently rebuilt the
Carter BBD on my '87 YJ 4.2L and am now discovering my mileage has been
cut in HALF! i was getting about 20mpg and am now lucky to get 10!
without going into too much detail, i rebuilt everything according to
the specifications that came with the kit and experienced no problems
except for one... the stepper motor shaft was pretty well frozen up, i
used a little spray lithium grease on it and got it moving again but it
was pretty damn stiff. most likely i suspect because it appears that at
least some of the control circuit for the carb is not functional.
specifically, the CTO valve is broken off (plug still in manifold but
vacuum assembly hanging), and the O2 sensor wire is disconnected
(sensor is still in manifold)... in this case i assume the stepper
motor would not function - correct?
thing is, she's apparently been like this for as long as i've owned her
(about 4 months) and was running acceptably well without any of this
stuff... so i'm assuming something i did in the rebuild is causing the
fuel suck. no clouds of black smoke or anything - just very very bad
mileage.
here's part 2 of the question - i've heard about people bypassing the
ICU completely - is that happening here? would i benefit from such a
procedure?
here's part 3 - any leads on a decent cheap rebuilt Weber or Holly or
anything else i can put on her? i've had nothing but frustration after
frustration with this Carter and its 'control circuit'... probably my
fault i know but i'd love to dump it. preferably on the head of the guy
who owned this thing for almost 20 years and apparently never took 5
minutes or $5 to see that she was taken care of... oh well.

thanks in advance - sorry for the long post.
cheers,
bennett

Consider that the previous owner "who owned this thing for almost 20 years
and apparently never took 5 minutes or $5 to see that she was taken care of"
got 20 mpg from it. 'nuff said.

It appears that you are looking for the "Nutter Bypass". This link should
help.

http://www.4x4wire.com/jeep/tech/ele...jn-ignition99/

Earle

"bobvonbob" > wrote in message
s.com...
> hey all - i'll try and keep it short. i just recently rebuilt the
> Carter BBD on my '87 YJ 4.2L and am now discovering my mileage has been
> cut in HALF! i was getting about 20mpg and am now lucky to get 10!
> without going into too much detail, i rebuilt everything according to
> the specifications that came with the kit and experienced no problems
> except for one... the stepper motor shaft was pretty well frozen up, i
> used a little spray lithium grease on it and got it moving again but it
> was pretty damn stiff. most likely i suspect because it appears that at
> least some of the control circuit for the carb is not functional.
> specifically, the CTO valve is broken off (plug still in manifold but
> vacuum assembly hanging), and the O2 sensor wire is disconnected
> (sensor is still in manifold)... in this case i assume the stepper
> motor would not function - correct?
> thing is, she's apparently been like this for as long as i've owned her
> (about 4 months) and was running acceptably well without any of this
> stuff... so i'm assuming something i did in the rebuild is causing the
> fuel suck. no clouds of black smoke or anything - just very very bad
> mileage.
> here's part 2 of the question - i've heard about people bypassing the
> ICU completely - is that happening here? would i benefit from such a
> procedure?
> here's part 3 - any leads on a decent cheap rebuilt Weber or Holly or
> anything else i can put on her? i've had nothing but frustration after
> frustration with this Carter and its 'control circuit'... probably my
> fault i know but i'd love to dump it. preferably on the head of the guy
> who owned this thing for almost 20 years and apparently never took 5
> minutes or $5 to see that she was taken care of... oh well.
>
> thanks in advance - sorry for the long post.
> cheers,
> bennett
>

Earle Horton wrote:
> Consider that the previous owner "who owned this thing for almost 20 years
> and apparently never took 5 minutes or $5 to see that she was taken care of"
> got 20 mpg from it. 'nuff said.

well - actually, she wasnt running at all for about 4 years... i
cleaned her up and fixed a few problems with the choke and then she ran
for ME getting about 20mpg... i was fairly happy with that - is that
low? i really have no idea...

thanks for the link to the nutter bypass, think i'll try it as it will
take at least some of the problems out of the equation.
question tho: does the CTO do anything after the nutter bypass? will i
still need to buy a new one?
thanks for your advice.
bennett

"bobvonbob" > wrote in message
oups.com...
> Earle Horton wrote:
> > Consider that the previous owner "who owned this thing for almost 20
> > years and apparently never took 5 minutes or $5 to see that she
> > was taken care of" got 20 mpg from it. 'nuff said.
>
> well - actually, she wasnt running at all for about 4 years... i
> cleaned her up and fixed a few problems with the choke and then she ran
> for ME getting about 20mpg... i was fairly happy with that - is that
> low? i really have no idea...
>
Twenty is pretty good for these beasts. The body aerodynamics are bad. My
more modern four cylinder fuel injected Wrangler only gets 24.

> thanks for the link to the nutter bypass, think i'll try it as it will
> take at least some of the problems out of the equation.
> question tho: does the CTO do anything after the nutter bypass? will i
> still need to buy a new one?
> thanks for your advice.
> bennett
>
I don't know if you will need it, but Mike Romain would.

Earle

Maybe you left off a vacuum hose somewhere?

Fred

"Earle Horton" > wrote in message
om...
> "bobvonbob" > wrote in message
> oups.com...
>> Earle Horton wrote:
>> > Consider that the previous owner "who owned this thing for almost 20
>> > years and apparently never took 5 minutes or $5 to see that she
>> > was taken care of" got 20 mpg from it. 'nuff said.
>>
>> well - actually, she wasnt running at all for about 4 years... i
>> cleaned her up and fixed a few problems with the choke and then she ran
>> for ME getting about 20mpg... i was fairly happy with that - is that
>> low? i really have no idea...
>>
> Twenty is pretty good for these beasts. The body aerodynamics are bad.
> My
> more modern four cylinder fuel injected Wrangler only gets 24.
>
>> thanks for the link to the nutter bypass, think i'll try it as it will
>> take at least some of the problems out of the equation.
>> question tho: does the CTO do anything after the nutter bypass? will i
>> still need to buy a new one?
>> thanks for your advice.
>> bennett
>>
> I don't know if you will need it, but Mike Romain would.
>
> Earle
>
>

Fred V. wrote:
> Maybe you left off a vacuum hose somewhere?
>
> Fred

is possible but i labeled everything and all the ports on the carb are
connected... the rest of the vacuum/emissions hoses are a disaster -
but then they've been like that as long as i've owned her.
i just did the nutter bypass today and also discovered that the timing
was somewhat off - 4 degrees BTDC. i just reset it to 8 BTDC and filled
her up - so we'll soon see.
thanks
b