why does my 99 chevy blazer idle rough and theres a very strong gas smell coming from exhaust. i replaced the plugs and cap and rotor. the check engine light is on all the time but when i punch the gas it flashs which mean a misfire. any ideas why its running rough with a very strong gas smell coming from exhaust with thick white smoke exhaust. i thought the head gasket but that was not it. any ideas?


Asked by Jan 04, 2016 at 06:05 AM about the 1999 Chevrolet Blazer 2 Door LS 4WD

Question type: Maintenance & Repair

5 Answers

Mark Grignon

the fuel spider assembly is known to fail in 4.3L engines. This will give you random misfire codes and often a flashing check engine light. If you can smell raw fuel from the exhaust, this is a definite symptom of a misfire. What is happening is raw fuel is being dumped into the exhaust manifold and some of the fuel could be igniting in the exhaust... not good. Your catalytic converter will surely result in damage. Get this looked at asap or it could run into a lot more $$$. The flashing cel is an indication that there is a "more than small" issue.

Best Answer

OK so u think if I change just the spider fuel assembly then that should cure it? Or do u think its more then just that?

Mark Grignon

Without a proper diagnosis, I am purely going by experience. I replaced the fuel spider when I was experiencing the same symptoms with my 99 Blazer. I went a little deeper with my troubleshooting. Fuel pressure, compression checks, ignition, were all tested and were within tolerance. So with that said, no guarantees. But I can tell you the fuel spider is known to fail on these engines and I would certainly suspect that as being the cause of your misfire.


OK. Thank u very much. I appreciate it. I'll replace that and see what happens.


Now, it is recommended to replace injectors, spider lines, and fuel regulator as an assembly. I have heard so many times after like 6 months there becomes the same problem when just replacing a specific item. Yea it is spendy but probably worth it.

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