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#11
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Clean your idle tubes.
"Dwayne Smith" > wrote in message news:fwgte.15015$R21.14011@lakeread06... > I have an 89 Jeep YJ 4.2L and I'm having a hard time keeping the engine > idling. I've rebuilt the carb and replaced a couple worn out vacuum lines. I > would replace and check the locations of all the vacuum lines however the > diagrams I have are not very helpful. I've checked the timing and made sure > the vacuum advance mechanism is working also. I can work the idle screw so > it will idle high and that helps, but then the engine RPM's are over 2K at > idle. > > Any help would be great!! > > Thanks, > > Dwayne > > |
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#12
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"Steve Foley" > wrote in message = news:Xzyte.16738$fa3.4412@trndny01... > "Dwayne Smith" > wrote in message > news:fwgte.15015$R21.14011@lakeread06... > > I have an 89 Jeep YJ 4.2L and I'm having a hard time keeping the = engine > > idling. I've rebuilt the carb and replaced a couple worn out vacuum = lines. > Clean your idle tubes. Look for raw gas dumping in the carb... is the needle and seat adjusted and working? How's the mixture smell? Take the idle vent tube off and watch for gas coming out. __ Steve .. |
#13
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That screams plugged up idle tubes to me.
The idle tubes are crimped at the ends and are basically too small so they plug up. A chemical clean will 'not' get them clear. I have seen 3 'professionally' remanufactured carbs that still had blocked tubes. The fix is to physically ream them out using a mini drill or file. I got my set of metered files at a welding supply house. They are used for cleaning torch tips. Here is a link to this Weber-Carter BBD fix: http://www.off-road.com/jeep/tech/engine/carter.html I have to do mine every couple years or shortly after running out of gas every freaking time. The carb gets bits of charcoal in it from the canister sometimes if you run it out of gas. The vacuum roars through the vent to the canister with no gas in the way in the float bowl so it sucks chunks. I was told the fix is to put a clear gas filter in the carb float bowl vent line to stop that but haven't got around to it. I have it down to a 15 minute trail fix if needed, if you take out the choke plate only, the venturi cluster will twist around and lift out without having to take apart the carb. A strand of copper wire will kick out the chunk or chop it so you can blow it through. One other sneaky one is the U tube from the filter to the carb. That sucker holds dirt and is steel so it rusts with alcohol gas mixes. Then the rust flakes get in and plug tubes. (The owners manual warns against 'any' alcohol mixes.) All this is assuming you didn't mess with the factory idle mix screw settings as the stepper motor takes them from factory set best lean idle and plays. The Nutter bypass mentioned will give a sweet 25% seat of the pants power boost and over 10 mph per gear extra, but you need to know how to set the idle mix on a carb properly to make it run. It won't fix something broken..... Theoretically is is illegal for emissions testing, but........ It will still pass the tailpipe emissions and if you leave all the junk in place the visual. I have been told but can't verify that somehow a visual and 'Nutter' just won't cut it in California, but doubt it. One other thing that can make the idle way high is a totally blown charcoal canister purge valve. Yours is old enough for that. The symptoms are piles of oil blowing into the air filter and a high idle. To test trace the PCV line to the back of the carb. There you will hopefully find a T fitting, but a solenoid thing will do. One line off that goes to the charcoal canister way down under the washer bottle on the firewall. At idle pinch this line closed. If the idle drops, the canister is dead. Hope this helps, Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Dwayne Smith wrote: > > I have an 89 Jeep YJ 4.2L and I'm having a hard time keeping the engine > idling. I've rebuilt the carb and replaced a couple worn out vacuum lines. I > would replace and check the locations of all the vacuum lines however the > diagrams I have are not very helpful. I've checked the timing and made sure > the vacuum advance mechanism is working also. I can work the idle screw so > it will idle high and that helps, but then the engine RPM's are over 2K at > idle. > > Any help would be great!! > > Thanks, > > Dwayne |
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