Topic: Intermittent Popping sound & dies at idle

[Osage1978]

First off thanks for reading this and offering to help, it's a little long but I tried to be detailed

My 82 22r that has a Weber 32/36 dgv & Davis HEI dizzy developed an intermittent issue. First some background on when how it happened. I was driving down a rough trail the other day mid day it was around 100 degrees outside. Truck was running normal temp & purring along when I hit a hole pretty hard. Once I crawled out of the hole the truck wouldn't idle and had a slight stumble/popping sound at low throttle. If I give it gas it smooths out and runs strong and smooth with an occasional slight popping, sputtering sound, not like a full on backfire. Going down the highway there is the slightest popping sound and that increases if I let off the fuel & most times it dies if I don't keep the rpms above 1000,1200

Drove it home and parked it & the next day it started up and ran perfect. Killed it and it sat all that day.

Next morning started and ran fine sitting in my driveway. Drove 1 mile to work and  as I pulled up to the job it started again, after work drove the truck home and pulled off the carb & tore it apart and cleaned everything that would come out or apart honestly it was spotless inside & out. Adjusted the float level that was slightly off, replaced the fuel filters, verified fuel pressure @ 2lbs coming into the carb, double checked the lean best idle setting, replaced the spark plugs, rotor & module. Have a cap coming with new wires. It has a minor vacuum leak where the throttle shaft goes in but it's always had that for the last 2 years and it's no worse now than years ago. Exhaust is in good shape no smashed pipe, carb adapter isn't cracked and no leaks there. Checked the vaccum advance line it's fine, brake booster hose is good

Once the Carb was back on it fired up & ran perfect for the next 4-5 hours then the same issue came back so I pulled the top looked it over, gave it some Carb cleaner out of desperation. Put it back together and it ran perfect. Next morning it was running rough again. Now it's a crap shoot if it'll run perfect or sputter & die at idle no matter if ii start it 10 times in a row. Engine temp has no bearing on the issue it's the same hot or cold,Checked the exhaust to see if it had any sucking with a dollar bill & there's none at all. I have an aluminum 10 gallon fuel tank in the bed & its clean & full with no vent issue.

Guys what am I overlooking or missing here? I'm at a loss as to what could be causing this to come & go

[sirdeuce]

If the hit was hard enough things could come loose, fall off or even break. I'd look for vacuum leaks at this point. Could be brake booster, try plugging off the brake vac line. check manifold nut and bolts for tightness and check the manifold for cracks. Power steering vac lines could be off as well as any other vac lines. Check VSVs for broken nipples.
Then the possible issues with the distributor. check for any loose connections. Open it up and test the components for looseness, pick-ups will do strange things when they get loose.  If there is enough play in the dist shaft contact between the rotor and cap is possible. Ign. wires could have developed cracks or bad connections. Cracks in the wires can cause cross firing.
Carb, check for loose bolts in the adapter and check whether or not the gaskets are in good condition, especially if it's the 2 piece adapter.
Electrical. Try moving the wire harness around when the engine is running, if there are any wires that jostled loose, like in a crimp connection. If the idle cutoff solenoid is getting an intermittent signal it could cause idle issues.

Just a few things off the top of my head, it's been a while.

[Gnarly4X]

Osage1978....

Excellent report!  I appreciate you taking the time to spell out the details so we have foundation and place to start.

Your issue is a mystery for me.  Typically its either fuel, ignition/electrical, or mechanical, right?

My gut feeling says it’s electrical. 

Ignitors usually fail completely.

Could be a loose connection – alternator wires, battery cables or ground, loose fuses?

When it fails, it wants to die.  Can you have someone help keep the engine running while you check the spark plugs and wires to see if it’s one of the cylinder not firing.

“Popping” usually indicates misfire, like ignition timing is off, cam timing, or valves.

This is a great tool for testing:

https://www.amazon.com/Ram-Pro-Engine-Ignition-Tester-Fool-Proof/dp/B01HU2L1NU/ref=sr_1_1_sspa?keywords=spark+plug+wire+tester&qid=1564482838&s=gateway&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExRDdHVDBTTkxTMlMwJmVuY3J5cHRlZElkPUEwMzkwODk1MjgyVkVOR1NMN1ZLSiZlbmNyeXB0ZWRBZElkPUEwMDczMzA2MldQNkxNMjVVUFA5NSZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

Can you put a timing light on it while it’s missing.  If not can you swap the distributor with someone to test ignition timing?

Mechanical…. Sticky valve?  When was the last time you check/adjusted the valve lash?

What kind of fuel pump are your running?

Based upon the “hit a hole pretty hard.”  It would appear to be related to a “jolt" which caused something to come loose – intermittent disconnect or short?

I'd want to try to rule out potential failures.

Have you read this?

https://22reperformance.com/faq-diagnostic-info

I'd call Jim at 22RE Performance and see what he says.

I’m still pondering your mystery.

Gnarls.

[emsvitil]

Sounds like something floating in and out of a carb passage to me.

[emsvitil]

I've also had crap get stuck in the needle valve causing an fuel overflow in the carb.

If it starts running crappy again, pinch off the fuel line to cut off fuel and see if it recovers.

[Osage1978 [OP]]

Thanks guys, work got crazy & haven't had much opportunity to dig deeper. I'll look at the things mentioned & report back if I discover anything