1979 CJ Won't start
- Thread starter mkbakker
- Start date
69jeepcj
New member
^^and or this^^
69jeepcj
New member
was that hose hooked to the pcv sucking air? (pulling vac). As I understand it, the pcv valve sucks unburnt fuel mixture back into the carb to be reburnt. so it sounds as if you are running rich and igniting unburnt fuel through your exhaust (back fire). not sure why the filter stopped it unless maybe the more air being sucked in by the filter diluted the mixture to the point it wouldn't ignite. This is a guess and not a sure cure, but I would try buying a new pcv and adjust the carb leaner. Their shouldn't be a filter on the pvc, it has to pull vac from the engine not the atmosphere.
Turbogus
Active member
hmmm wouldn't a backfire through the carb be a lean condition? I think the OP mentioned his spark plugs were white. While out the tailpipe be indicative of a rich condition? Not to sound a smart@ss I've been working on my Jimmy too and my mind is a little clogged, better break out the Draino.
69jeepcj
New member
I always thought backfire through carb was rich, I could be wrong. white plugs do indicate lean though! being there in person would be a lot easier to diagnose than the intro net. Can the OP give a update? When I got my jeep, It ran decent but would backfire, buck and stumble at times, turned out cam was gone. Another time I had issues with backfire, it was cured by resetting the timing and carb adjustment.
greg92jeepxj
Official Supporter
Good call . A non functioning or partially open EGR valve should not be overlooked . It will produce an over rich mixture at idle and will be pronounced as you accelerate . The result is backfiring . Instead of just pulling the vacuum line , pull the EGR valve and clean the port as well as the valve . If cleaning the valve is too cumbersome , unpractical or not worth the time , replacement is the best option.
greg92jeepxj
Official Supporter
old jeeps never die , they just get rebuilt , again .
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