My 2002 Pontiac GP V6 smells like rotten eggs from the exhaust

Clogged exhaust or over rich fuel mixture.

black smoke indicates that it is over fuelling, probably from a faulty injector
the eggs smell is hydrogen sulphide ( rotten egg gas) and is the cat converter doing its job ( same as new car exhaust smell)

rotten egg smell is hydrogen sulfide from catalytic converter not burning all hydrocarbons and or poor air fuel mixture., you may have to trace out power wire lead that it is getting power to fuel pump, as well as ground wire that control pump. when you say relays are good do you hear them activate when you turn key on , switch relay out with knowen good one .,you can try a little starting fluid if it runs on that you know all other electrical is performing well , then back to plan A . Woody

it is happen to old engine because the oil that escape from the engine(engine cover near the exhaust) when it is got hot it sends bad smell but after how many minutes if it already dried up because of heat it will gone (like frying using the used cooking oil in pan there is a different smell).

converter sounds like it has clogged up. Might be using more gas now too.

If car runs okay with egg smell, its normal and working the way it should, if car is running poorly and the rotten egg smell has gotten worse, its a sign that your exhaust catalytic converter will need to be replaced. good luck!

That rotten egg smell is unburnt fuel in the exhaust. I am no expert in ignition systems but i have heard that optispark systems aren't very hardy. Try replacing the coils, wires, and plugs. If that doesn't work its time for a new distributor.

1 Inspect OXYGEN Sensor Damaged or Faulty OXYGEN Sensor or Circuit. 2 Inspect Timing Specification Incorrect Ignition Timing. 3 Inspect Catalytic Converter Clogged or Faulty Catalytic Converter. 4 Inspect PCV Valve Plugged or Damaged PCV Valve. 5 Inspect Carburetor Dirty and Improperly Functioning Carburetor. 6 Inspect Hose (PCV)at Clogged or Collapsed PVC Hoses.

did he gap the plugs properly? sulfur smell comes from excess fuel being dumped into the exhaust (catalytic converter). Could be the coil, or improperly gapped plugs. If the wires were out of order, there would be a misfire.

What does it smell like? If it smells like rotten eggs that is a tell-tale sign that your catalytic convertor is bad.