The truck: '07 H3 base model, basically stock with Air Doc intake. For a while I've had this problem where the car starts up cold just fine. If I drive it for a while (so it gets up to temperature) and shut it off then immediately restart it, it starts fine. If I let it sit 10-15 minutes and then attempt to restart, it will crank and sometimes cough and sputter, but it won't catch. It used to be a 30 minute wait would be sufficient, now it's up over an hour, but once the problem has cleared, it will start fine once again.

I've noticed that I always have a P0171 code after clearing and then driving for a bit. If I check after more driving, I get some others...a P0300, sometimes a P1133.

I've cleaned my air filter, cleaned the MAF and cleaned the throttle body. The air filter was fairly dirty, but there was nothing visibly amiss with the MAF or TB, and not surprisingly, this didn't help.

It's getting worse, too (unless it's something different). Sometimes now if you are idling it will shut off on its own.

There's a thread on here from about a year ago where someone described these identical symptoms and fixed it by replacing a fuel pump. However, the one shop I called quoted me over $900 ($600 in parts) and said they would know if there was a cheaper option "once they pulled the part and had a part number," which is nonsense. I can get the AC Delco pump off Amazon for <$300. But I'm a bit leery of pulling the tank and attempting it myself.

Does this sound like a fuel pump? The one thing I don't know from the previous thread is if he was seeing the same codes. If this seems likely, maybe I should just bite the bullet and have them do it...

 

First diagnose P1133 CHEVROLET code

• Check the "Possible Causes" listed. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded terminals.

P1133 CHEVROLET Possible Causes

• Faulty Heated Oxygen Sensor (HO2S) Bank 1 Sensor 1
• Vacuum leak
• Faulty Heated Oxygen Sensor (HO2S) Bank 1 Sensor 1 harness is open or shorted
• Faulty Heated Oxygen Sensor (HO2S) Bank 1 Sensor 1 circuit poor electrical connection

 

I believe this refers specifically to the upstream sensor, is that correct? I read that in another discussion somewhere...

 

Yes, on the EM...

Btw, you could simply check fuel pressure before throwing parts at it.

Here's a vid of a simple fix for P0171 after parts were thrown at it:

 

A common issue with I5 H3s is the intake manifold fasteners vibrate loose and cause a leak downstream from the MAF = P0171. Check all those are bolts are tight, if loose TQ to 10 N.m (89 lb in).

NICE job on the thread.

 

Not sure what I thought I would accomplish replying to a year old thread :-D

I will check those bolts. I forgot to mention that I recently had the starter replaced, but I don't know for sure if they removed the intake manifold per the WSM or went in through the wheel well.In any case, this problem predates the starter issue.

 

I may be jinxing myself, because I haven't tested this out very much since I got the truck back, but I found a shop that would put my fuel pump in if they agreed that was the likely problem (I had it there anyway because of a massive transmission fluid leak that sprung up) and it seems to have fixed the hot start problem. I'm no longer seeing the O2 sensor codes either. If there are any further developments with this, I will post, but cross your fingers, I won't have to.