4.2L Stalling Problem - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 01-01-2003, 07:47 AM Thread Starter
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4.2L Stalling Problem

My son’s ’89 YJ with a 4.2L and a Carter BBD stalls occasionally when he comes up to stop signs and lights. He normally has it in neutral and coasting to the stop when the engine just dies. It will restart without any hesitation and idles smoothly. I have drilled out the idle air tubes and it has the TeamRush TFI ignition mod but we haven’t done a Nutter by-pass yet. Anyone have an idea what is acting up?
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post #2 of (permalink) Old 01-01-2003, 08:12 AM
 
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Re: 4.2L Stalling Problem

im not really too familiar with that carb, but it sounds like maybe the fuel sloshing out of the bowl. you might try adjusting the float, and making sure it doesnt have a pinhole in it, and is filling up with gas. [img]images/graemlins/givemebeer.gif[/img]
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post #3 of (permalink) Old 01-01-2003, 09:52 AM
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Re: 4.2L Stalling Problem

try purge line on evaporation canister



Evaporation Canister

The evaporation canister can be found mounted on the firewall just in front of the driver's feet. It's the size of a coffee can and has four hoses attached. From left to right in the photo they are:
1. Purge signal (ported vacuum)
2. Purge line (manifold vacuum)
3. Line from fuel tank
4. Line from carburetor bowl


DETAILS


--------------------------------------------------------------------------------

The object here is to prevent the escape of gas vapor into the atmosphere while the engine is not running. A functioning gas cap has a two-way relief valve in it that forces evaporating gas up a vapor tube into the engine compartment and into the evaporation canister, where it is trapped in charcoal. Gas evaporating from the carburetor is routed here also.

When the engine is started and warmed up, ported vacuum at the "purge signal" cap opens a valve and the trapped vapor is pulled into the carburetor by way of the purge line and burned.

Canister purging should not take place at idle or when the engine is cold, when the CTO should prevent ported vacuum from appearing at the canister.

This canister can make trouble if the purge diaphragm under the little cap is leaking, which forces the engine lean, resulting in a rough and unsteady idle.

A simple test for this is to use a pair of long-nose pliers to squeeze the main purge line shut while the engine is idling. There should be no change in the idle. If there is, head on down to your local friendly Jeep dealer with $68 in your hand for a new canister.





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post #4 of (permalink) Old 01-01-2003, 11:17 AM
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Re: 4.2L Stalling Problem

Since you say that it idles fine and starts right back up ..it would appear to be a throttle transition problem.

Does it happen if he just revs it when he's coasting in neutral? Does it happen if he just revs it when he's sitting there not moving?
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post #5 of (permalink) Old 01-01-2003, 01:49 PM Thread Starter
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Re: 4.2L Stalling Problem

It revs and idles just fine after it stalls. I haven't been able to duplicate the stall in the driveway. I will do the purge line test this weekend.
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