8thNote
OBS Enthusiast
Hello, I am new to the forum and this is my first post. This forum seems like a great resource and I look forward to becoming an active member of the community.
I have a 94 C1500 extended cab short bed (Silverado trim) in Summit White. It has the 5.7L TBI engine with 196k miles on the original engine and trans. The truck is in immaculate condition both inside and out (had a respray in original color 2 yrs ago) and very original. The only mods are an open-element 14" air cleaner and a single glass pack muffler with a short turndown tail pipe.
Until recently, the truck ran great. A couple of months ago though, it started to sputter, hesitate, and backfire. Right before it starts to sputter, I can feel a noticible loss in power, like the engine is bogging down. It usually only does it under heavy throttle application or while cruising at 70+ mph. Also, it only happens when the engine is hot (180-200 degrees water temp). I have replaced the fuel filter, spark plugs, wires, distributor cap, and rotor button and the problem still persists. I noticed that a rubber fitting from the fuel tank vent line going into the charcoal canister was dry rotted and cracked, so I replaced that fitting as well. All the rest of the vacuum lines seem to be in good condition. All of the sensors and their wiring harnesses are attached and appear to be in good condition. There is no CEL light on. When the truck is running good, it runs great. Fuel milage is consistently in the 14-15 mpg range and power feels adequate 95% of the time.
I am at a loss as to what is causing this sputtering and backfiring. Does anyone have any thoughts or suggestions as to what I should try next? I greatly appreciate any and all advice and thank everyone in advance!!
I have a 94 C1500 extended cab short bed (Silverado trim) in Summit White. It has the 5.7L TBI engine with 196k miles on the original engine and trans. The truck is in immaculate condition both inside and out (had a respray in original color 2 yrs ago) and very original. The only mods are an open-element 14" air cleaner and a single glass pack muffler with a short turndown tail pipe.
Until recently, the truck ran great. A couple of months ago though, it started to sputter, hesitate, and backfire. Right before it starts to sputter, I can feel a noticible loss in power, like the engine is bogging down. It usually only does it under heavy throttle application or while cruising at 70+ mph. Also, it only happens when the engine is hot (180-200 degrees water temp). I have replaced the fuel filter, spark plugs, wires, distributor cap, and rotor button and the problem still persists. I noticed that a rubber fitting from the fuel tank vent line going into the charcoal canister was dry rotted and cracked, so I replaced that fitting as well. All the rest of the vacuum lines seem to be in good condition. All of the sensors and their wiring harnesses are attached and appear to be in good condition. There is no CEL light on. When the truck is running good, it runs great. Fuel milage is consistently in the 14-15 mpg range and power feels adequate 95% of the time.
I am at a loss as to what is causing this sputtering and backfiring. Does anyone have any thoughts or suggestions as to what I should try next? I greatly appreciate any and all advice and thank everyone in advance!!
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