Rough idle and stalling: 1988 YJ 258CID, Carter Carb, 5-sp

[sl0th]

All--

I have a friend who has acquired a 1988 YJ, 258CID, Carter Carb, 5-sp.

At idle, the carb is not atomizing fuel, and it basically just drips down the
throat, causing it to either stall or run like hell.

I have seen the URLs that describe some of the issues, like:
http://www.off-road.com/jeep/tech/258bbd/index.htm
http://www.off-road.com/jeep/tech/engine/carter.html

The recommendations on those sites were performed, and still no luck.

o The O2 sensor has just been replaced
o A carb kit was installed
o The carb was cleaned when the carb kit was installed
o New plugs were installed

If the stepper motor molex connector is removed from the socket, the
engine runs just as badly. At times, if you rev the engine, you can see
the metering pins in motion, which tells me the stepper motor is working,
but perhaps not.

Does anyone have any experience with a similar issue along these lines?

Thanks for any assistance/info!

[dirtrider]

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

[MattPascoe]

When you say the fuel just drips down the throat, is that at idle, or when tapping the accelerator?

On mine, at idle you could not see fuel flowing or atomizing. But the accelerator pump sprays a crappy, drippy stream when you hit the throttle.

If it is dribbling at idle you probably need to try that "easy fix" link again.

MP

[sl0th]

-=- originally posted by MattPascoe -=-
When you say the fuel just drips down the throat, is that at idle, or when tapping the accelerator?

Fuel is _pouring_ in...at idle. Once there is enough air coming in, say half
throttle, I can see the fuel turn from a liquid to a vapor.


On mine, at idle you could not see fuel flowing or atomizing. But the accelerator pump sprays a crappy, drippy stream when you hit the throttle.


Yes...the accelerator pump just squirts raw, unvaporized fuel in, which is
OK at those throttle settigns where it operates. But the raw, unvaporized
fuel at idle is making it so rich and uneve mixture-wise, it will just stall out
after running terribly rough.


If it is dribbling at idle you probably need to try that "easy fix" link again.
MP

Might have to; problem is, is that others (the owner) are doing the work,
plus they took it to a lube-n-tune place, and that guy plain just got lost.
The owner is looking to get a Holley ProJection kit or something, which is
where I'd put my money.

Was just hoping there was something he'd left out that someone might
key in on. He might hafta re-do the off-road.com steps again, although I
trust his abilities as a mechanic.

[frontlander]

The Carter is a lost cause, in my opinion. They can be fiddled with and tweaked but they end up running crappy again. The cheap fix is to do the Motorcraft 2100 swap. I did it on my 258/Carter and it was the best mod I've done to my Jeep. From there it is just a matter of how many dollars he wants to spend (Weber carb, throttle body injection, Mopar).