258 stalls at idle

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Micah - 12 Mar 2007 20:30 GMT

Me again. My 1988 4.2 YJ is once again giving me problems. Just
installed a rebuilt 2bl Carter 2 weeks ago. Flushed the fuel lines
and changed the filter when I did it. First had problems with the
choke pull-off, I didn't have that fixed for a day before I started
having more trouble. Now, hot or cold, it just won't idle. When I
push the clutch in to come to a stop, the RPMs fall first to about
1000, then to about 200, then the engine dies. It does it with or
without the brakes applied. I checked everywhere for vacuum leaks on
Saturday, found only one, and subsequently fixed it. It still doesn't
idle. I checked the EGR for proper operation (the pintle moves back
and forth at high RPMs as I believe it should). Plugged off the vac
line to the brake booster and still, it stalled. The vac reservoir
under the battery also functions. I pulled my distributor cap, it was
clean as a whistle in there. My spark plugs have about 300 miles on
them, and yes, I gapped them correctly.

Other information that may or may not apply to the situation: it
didn't start doing this progressively. It ran perfect all day, then
at one stoplight, it just died. Also, since it started happening, I
can smell melting plastic coming from somewhere under the hood, but I
can't for the life of me locate the source. Does anyone have ANY
ideas? I'm at the end of my rope.

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L.W. (Bill) Hughes III - 12 Mar 2007 21:05 GMT

Did you replace the fuel filter rather hidden inside the frame rail, on
the drivers side above the front half of the
spring. There's a shield you have to remove to get to it?
God Bless America, Bill 0|||||||0
mailto:LWHughes3rd@aol.com http://www.billhughes.com/

> Me again. My 1988 4.2 YJ is once again giving me problems. Just
> installed a rebuilt 2bl Carter 2 weeks ago. Flushed the fuel lines
[quoted text clipped - 18 lines]
> can't for the life of me locate the source. Does anyone have ANY
> ideas? I'm at the end of my rope.

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Micah - 12 Mar 2007 21:25 GMT

My fuel lines don't go near there. Just checked.

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The Merg - 12 Mar 2007 21:39 GMT

Bill, is that a second (or rather, first) fuel filter? My filter sits
next to the carb, but if there's another one we neglected to replace,
that could be an answer to some problems.

> Did you replace the fuel filter rather hidden inside the frame rail, on
> the drivers side above the front half of the
[quoted text clipped - 24 lines]
>> can't for the life of me locate the source. Does anyone have ANY
>> ideas? I'm at the end of my rope.

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Micah - 12 Mar 2007 22:53 GMT

Well everyone, I solved my own troubles. My carb is two weeks old, it
can't be broken, right? Wrong. As a last resort, I pulled the venturi
cluster, found that my drivers' side idle pickup tube had fallen out
of its hole. Cleaned 'em both up for good measure, pushed the one
into the assembly, and put everything back together. Started it up,
and it just purred. On the bright side, in the process of fixing this
thing I fixed a vacuum leak and tested most of my emissions stuff - so
everything should be working fine for a while now.

Going to take a shower and get to the grocery store - Haven't been
there since this started happening and I'm getting pretty hungry.

Thanks for your help, Bill.

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Mike Romain - 12 Mar 2007 23:25 GMT

The gas line from the filter to the carb has a U shape and is notorious
for holding enough junk in it to plug up an idle tube. I see that lots
just after a carb kit job if folks don't clean that line out.

To see if this is it, at idle carefully look down the carb throat and
give the gas a shot with your hand on the linkage. You should see two
nice sprays of gas in there. If you see drips of gas, then the idle
tubes are plugged up.

Here is a link on fixing that problem. The idle tubes can be pulled
from the top if the choke plate is out of the way and cleaned. They
twist and clear the choke rod also. They need a physical ream at the
crimped end or better an oversize using a welding torch tip tool. Those
are small drill bits or files.

http://jeep.off-road.com/jeep/article/articleDetail.jsp?id=277064

Rebuilders won't normally physically ream tubes, they rely on chemicals
which won't always work on these carbs.

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!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)

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!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)

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Highcountry - 13 Mar 2007 14:40 GMT

Just adding a note about a FREAK happening that just about drove me
wild!

When I got my 86 CJ it suffered from the common malady of the NOX
reduction "enrichment system" causing it to load up and die at idle.
Being an "old geezer" from before the EPA forced Carter to ruin the
BBD, I simply modified my BBD carb to eliminate the useless "enricher
motor" on the rear and re-set everything to old style specs while also
performing the "Nutter Bypass" to eliminate the no longer used
circuitry.

The CJ ran flawlessly for about 3 years and then started sputtering at
idle. "What the...?", I thought. So all through the carb I went
searching for the culprit. Found it floating around under the "idle
tubes". Where did this piece of flotsam come from? I found that
out as well, starting the Jeep and letting it run with the lid off the
air cleaner during adjustments I noticed that the "Air Injection"
hoses that branch off the back of the cleaner went through a stage
during warmup where they sputtered a little condensate back into the
air cleaner housing. Amongst that condensate were some tiny flakes
of "crud" just like the one I had removed! If one of these just
happens to make its way over to the float bowl opening, it will
eventually find its way to the "idle tubes" and repeat the problem.
I know it is a "long shot" but it was the logical reason for the
problem considering the surgical clean rooom method I use when
tinkering...

Those little problem makers are now disabled, and I don't plan on
tearing apart my BBD for another 10 years or so until the pump and
needle are tired!

Bruce

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Mike Romain - 13 Mar 2007 15:21 GMT

> Just adding a note about a FREAK happening that just about drove me
> wild!
[quoted text clipped - 28 lines]
>
> Bruce

I find I need to clean my float needle and seat every couple years. I
also needed emissions every couple years so I would normally just kit
the carb for $20.00 and have everything new. Those are really easy
carbs to kit.

I 'think' I know one source of your black chunks in the float bowl.

If you run that 258 engine out of gas when warmed up, the charcoal
canister is active because of the hot coolant in the CTO valve. Then
when you are trying to start it up, the choke will automatically be
closed which puts high vacuum on everything which will sometimes suck
charcoal bits out of the canister.

I have had this happen to me and have seen it happen to others. One
person from this group I think it was put a clear inline gas filter in
the vent line to the carb float bowl to prevent this from happening. He
reported finding bits of charcoal in the filter.

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!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)

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