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saulfun1971's avatar
saulfun1971
Explorer
Jul 08, 2014

454 Back fire thru exhaust

I have an 88 Gulf Stream Sunsport that I recently bought. It has been sitting for 2 years and it runs good except at about 50 to 55mph it back fires thru the exhaust. E have changed plugs and wires and rebuilt carb. Does anyone know if it has an inline fuel filter? Also the distributor and coil looks new inside?

12 Replies

  • A filter isn't going to make it backfire through the exhaust.
    Did it do that before the new plugs? Does it do it more under a load? Is there a stumble feeling? (EGR)
    If a plug gets cracked during installation it can act like that.
    You could also have one or more valves sticking because it sat so long. Running some good fresh fuel with a can or two of Seafoam through it may take care of that if it's the case.
  • There should be a large in line filter along frame rail just in front of right rear wheels.
    Carb getting rebuilt should have taken care of filter in the inlet port there.
    Backfiring is more likely to be electrical. Check to make sure the plug wires go to the correct one.
    Check the EGR valve and vacuum control lines.
    Does the back firing happen during acceleration or deceleration?

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