Hello. Bought a Blazer and after my initial inspection I thought it would be good to go. (I inspect as thoroughly as I can but I admit I don’t have much mechanical knowledge). Vehicle has 162k miles.

It cold starts no problem, idle is consistent, shifts smooth. I didn’t notice any issues on my test drive. I went back a day later and bought it. Again it cold started just fine and had no issues. I drove it for 15 minutes and then stopped to eat.

The vehicle sat for 5-10 minutes and when I back out it started up and died almost immediately. Then I went to turn the engine over again and it just clicked. Then I tried a 3rd time and it started up. After this I drove home and it continued to drive fine.

the battery is new as of 6/24 from what the sticker says. I was able to replicate the start-die, no start-clicks, and finally starting issue again after running it for a while and then shutting it off for a few minutes. After replicating that issue, once I got it running I shut it off and started it 2 more times. Both times it fired up immediately.

I then scanned it and got codes P0171, P0174, and P0122.

I changed the o2 sensor and cleared the codes. Took it for a drive and they came back. I wasn’t really expecting that to be my fix though.

I tried to do a vacuum leak test with carb cleaner while the engine was cold. I wasn’t able to make the RPMs change at all doing this. I also hooked up a pressure gauge. My reading was right around 16-17 hg. When I blipped the throttle it went down, then shot to around 22-23 hg then settled back down to 16-17 hg.

I found this reading appeared to be in a healthy range (from what I read). Then the diagnostic tool showed the absolute pressure to be 36kPa which I translated to about 10.6hg which would be on the low end. So what gives with this??

I also hooked up a fuel pressure gauge. My initial reading was about 50. It then slowly decrease. I believe from what I read that I have an issue there for sure as I think the pressure decreased to quickly.

tomorrow I plan to change the TPS and check the throttle body to see how clean it is.

one other thing I noticed is at the air intake, one of the clamps is loose. Would this possibly cause any of these issues or is the underlying issue deeper?

please advise. I feel like I got screwed In this car deal and I don’t have the heart to turn around and screw someone else the same way.


Edit to add: also after running all the test I mentioned above, I went to try and replicate the start-die, no start- clicks, and start issue again. This time after the vehicle ran for a while and was at operating temps, I shut it off for around 5-10 minutes. When I went to start it 1st try was just clicks, 2nd try was just clicks, and 3rd try was some clicks before finally turning the engine over. It didn’t die, ran and idled fine.

pleaseeee help :,) feeling extremely discouraged right now

 

If the intake leak is after the maf sensor then that could explain the lean codes.

You need to resolve the fuel pressure leak down issue before we go any further.

George

 

Regarding the click no start. Bring a digital multimeter and a helper with you. When the truck dies and wont start, only clicks, crawl under the truck and measure the voltage first on the purple wire during an attempted start and then again on the large black battery cable.

George