Guest fmbjogger Posted April 12, 2012 Share Posted April 12, 2012 My '74 DeVille was backfiring after punching the pedal. After first muffler blowout, rebuilt carb, replaced vacum lines and replaced divorced choke pulloff.....BANG....second blown muffler. Now I'm pissed.Checked with an old carb guy and he suggested I check pollution pump setup. Pulled the line and....no backfire. bypassed the system and all is right in Cadillac world.Can anyone explain what's up with system ? Thanks ! Link to comment Share on other sites More sharing options...
Alfre Posted April 12, 2012 Share Posted April 12, 2012 Replace the Rochester valve This is the only name I know it by it normally is located above the pollution pump.Al Link to comment Share on other sites More sharing options...
Guest fmbjogger Posted April 12, 2012 Share Posted April 12, 2012 Thanks, Alfre. I'll check it out. Link to comment Share on other sites More sharing options...
NTX5467 Posted April 17, 2012 Share Posted April 17, 2012 How about "diverter valve"?While you're under there, be sure to check the two check valves, one on each of the distribution manifolds. When they get weak (there's a rubber diaphram in the valve), they let hot exhaust gases get upstream toward the diverter valve and air pump. "Things melt" from that kind of heat where it shouldn't be!Just some thoughts . . .NTX5467 Link to comment Share on other sites More sharing options...
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