2001 monte carlo
3800 series 2
When tempature starts to get cold out, car always does a small backfire on 1st start of the day.
It hasn't done it all summer, but did last year when it was cold out ?
Any ideas or tests I could do.
Last year, I cycled the fuel pump 2 times before I cranked it and that seemed to help.
Thanks in advance !!
Goatman

 

Are these legit backfires? If so, I'd be very worried about blowing up the intake / potential for fire. Unfortunately not uncommon on 3800s.

First thing I'd check is the FPR to see if it's leaking fuel into the intake.

 

I had the whole regulator, catch on fire, blow plenum apart issue about 5 years ago. not covered by recall in 2001. but covered in 2002. Whole different delema...
it's just a small backfire, but smoke does come from under the hood.
I just kept cranking it and it fired right up after the backfire.
I was thinking I'd check Fuel pressure when key is on 1st cycle in the morning, maybe pump is bleeding off at night?

 

Have you 100% ruled out the FPR since its so easy? It wont necessarily have the exact symptoms each time they fail.

Checking the pressure is also a good idea. Could point to a leaky injector or several.

 

No I haven't checked the regulator, Whats the best way to check it?
I will check fuel pressure tomorrow.
thanks !!

 

Just pull the vac line off and smell/check for gas. Have the car running first. Give it a few minutes, sometimes it takes a few to spit some gas out.

 

Assuming those dates aren't typos, that was literally 20 years ago. Absolutely possible for it to fail again from age. It's just a simple diaphragm inside that can leak / deteriorate.

How is the battery? It's not uncommon on 3800s for spark timing to get a bit wacky if voltage is very low / cranking is ultra slow right at first. But if it's doing this every time even if electrical is strong, then it's probably something else.

How does it run otherwise - fuel trims / vac levels ok?

​​​​​​Shouldn't have to go through 2 full prime cycles to get pressure again though, the lines are pretty small in volume even if dry.

I also wonder about injectors. Id be curious to prime it, then pop the rail and injectors off real quick to take a look / sniff. Wonder if one is draining the rail into the engine after it sits for a bit?