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73-87 Chevy _ GMC Trucks => Fuel Systems and Drivability => Topic started by: Jp87v10 on September 13, 2019, 03:47:19 PM
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Got a code 45 today with my 350 tbi, o2 sensor is new.
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Something may be making it rich. Make sure injector isn't leaking.Does the canister have liquid fuel in it. Map sensor vacuum good? Low vacuum to map or bad map. Pull line off map and make sure you have good vacuum. That port at throttle body can get clogged with carbon. Fuel pressure regulator problems can raise fuel pressure and cause rich condition. Also I have seen restricted fuel return lines cause pressure to be high. If the lines at the tank were ever replaced and not routed properly they can get pinched. Fuel selector valve not switching completely could be a problem.
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Okay thanks I'll check the canister first. I know I replaced the throttle body when I got the truck and all the sensors. I dont have the AIR pump anymore. Could that cause it?
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The air pump only pumps air when warming up In open loop. If it was pumping air during closed loop it would set a lean code. Having no air pump would not effect the O2 sensor rich or lean.