1999 Blazer, lots of mileage! Turns over well but doesn't start but can leave it for an hour or less and it will start and run pretty good! But, it backfires and there is a strong gas odor when it starts up. But then it settles down and runs!!! One time though, it stalled out. I replaced fuel filter - fuel pump was replaced over a year ago... Thanks for your help.

 

Welcome to the forum!


Backfires through the intake or exhaust? If it's through the intake, replace the distributor cap & rotor with AC Delco parts. Don't even think about wasting your time and or money on aftermarket stuff

 

Thank you - truck backfires through the exhaust - thought I had a hole in the muffler or tail pipe but that's ok.

 

Do the distributor cap & rotor first and then post the results.

 

It is fuel injected. This morning it didn't start but turned over. In a few hours it will probably start and then run ok throughout the day.

 

While the engine is cranking, and not starting, the injectors are still squirting fuel, flooding the engine. When the engine starts, it probably runs rough for a few seconds until the excess fuel is cleared out.


A rich fuel mixture can not cause a backfire, (too much fuel puts the fire out). Spark at the wrong time will cause a backfire. If there is excessive crossfire inside the cap, (not going to the correct spark plug at the correct time) it can cause a no start condition.


Replace the cap & rotor and post your results

 

If that doesn't work, replace ignition switch with ACDelco part

 

Just a thought, but when I took off the plenum the first time, and put it all back together, the connector on the passenger side of the throttle body looking from the front of the engine, was whistling at first as I press the gas pedal. It didn't do that before, even when I bought the truck. It doesn't whistle anymore, but I'm thinking that connector is faulty... What connector is this and what is it's function? (the connector on the passenger side of the throttle body looking from the front of the engine)