Having trouble keeping it going

Clean your idle tubes.

"Dwayne Smith" > wrote in message
news:fwgte.15015$R21.14011@lakeread06...
> I have an 89 Jeep YJ 4.2L and I'm having a hard time keeping the engine
> idling. I've rebuilt the carb and replaced a couple worn out vacuum lines.
I
> would replace and check the locations of all the vacuum lines however the
> diagrams I have are not very helpful. I've checked the timing and made
sure
> the vacuum advance mechanism is working also. I can work the idle screw so
> it will idle high and that helps, but then the engine RPM's are over 2K at
> idle.
>
> Any help would be great!!
>
> Thanks,
>
> Dwayne
>
>

"Steve Foley" > wrote in message =
news:Xzyte.16738$fa3.4412@trndny01...
> "Dwayne Smith" > wrote in message
> news:fwgte.15015$R21.14011@lakeread06...
> > I have an 89 Jeep YJ 4.2L and I'm having a hard time keeping the =
engine
> > idling. I've rebuilt the carb and replaced a couple worn out vacuum =
lines.

> Clean your idle tubes.

Look for raw gas dumping in the carb...
is the needle and seat adjusted and working?
How's the mixture smell? Take the idle vent
tube off and watch for gas coming out.
__
Steve
..

That screams plugged up idle tubes to me.

The idle tubes are crimped at the ends and are basically too small so
they plug up. A chemical clean will 'not' get them clear. I have seen
3 'professionally' remanufactured carbs that still had blocked tubes.

The fix is to physically ream them out using a mini drill or file. I
got my set of metered files at a welding supply house. They are used
for cleaning torch tips.

Here is a link to this Weber-Carter BBD fix:

http://www.off-road.com/jeep/tech/engine/carter.html

I have to do mine every couple years or shortly after running out of gas
every freaking time. The carb gets bits of charcoal in it from the
canister sometimes if you run it out of gas. The vacuum roars through
the vent to the canister with no gas in the way in the float bowl so it
sucks chunks. I was told the fix is to put a clear gas filter in the
carb float bowl vent line to stop that but haven't got around to it.

I have it down to a 15 minute trail fix if needed, if you take out the
choke plate only, the venturi cluster will twist around and lift out
without having to take apart the carb. A strand of copper wire will
kick out the chunk or chop it so you can blow it through.

One other sneaky one is the U tube from the filter to the carb. That
sucker holds dirt and is steel so it rusts with alcohol gas mixes. Then
the rust flakes get in and plug tubes. (The owners manual warns against
'any' alcohol mixes.)

All this is assuming you didn't mess with the factory idle mix screw
settings as the stepper motor takes them from factory set best lean idle
and plays.

The Nutter bypass mentioned will give a sweet 25% seat of the pants
power boost and over 10 mph per gear extra, but you need to know how to
set the idle mix on a carb properly to make it run. It won't fix
something broken.....

Theoretically is is illegal for emissions testing, but........

It will still pass the tailpipe emissions and if you leave all the junk
in place the visual. I have been told but can't verify that somehow a
visual and 'Nutter' just won't cut it in California, but doubt it.

One other thing that can make the idle way high is a totally blown
charcoal canister purge valve. Yours is old enough for that. The
symptoms are piles of oil blowing into the air filter and a high idle.

To test trace the PCV line to the back of the carb. There you will
hopefully find a T fitting, but a solenoid thing will do. One line off
that goes to the charcoal canister way down under the washer bottle on
the firewall. At idle pinch this line closed. If the idle drops, the
canister is dead.

Hope this helps,

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Dwayne Smith wrote:
>
> I have an 89 Jeep YJ 4.2L and I'm having a hard time keeping the engine
> idling. I've rebuilt the carb and replaced a couple worn out vacuum lines. I
> would replace and check the locations of all the vacuum lines however the
> diagrams I have are not very helpful. I've checked the timing and made sure
> the vacuum advance mechanism is working also. I can work the idle screw so
> it will idle high and that helps, but then the engine RPM's are over 2K at
> idle.
>
> Any help would be great!!
>
> Thanks,
>
> Dwayne