Starting issue

[ND-1965C10]

Recently purchased a 2003 Trailblazer with the 5.3. 141K on the clock. I think it had little use the last two years.
This week my wife told me it has been starting hard. I give it a shot and see that it cranks fine but sometimes does not 'fire'. Thought is could be ignition or maybe fuel pump? Once running overall runs fine. Just waiting to have it not start and seems to be getting worse. Thoughts on where to start? I do have a couple engine codes related to the Knock Sensors and O2 Sensors but those seem to not be related. Will be tackling those in the coming weeks.

 

[murdog]

Start by checking the fuel pressure. Also are you hearing the fuel pump when you turn the key? Also if it fails to start try cycling the key. The check valve in the fuel pumps can fail and allow all of the fuel in the system to flow back into the tank, and the fuel pump cannot prime the fuel system fast enough to start the engine right away. So start with fuel, but also take care of those OBD2 codes since the knock sensors are probably not helping the situation.

 

[linneje]

Just a thought, but seeing if the fuel filter has been changed is a place to start. When I changed mine a couple of years ago, the insides just poured out. Since the filter has very easy access and it is a cheap part, you might start there. If it is still the original, it will need replacing anyway.

 

[ND-1965C10]

Wanted to get an update on this. It ended up being the fuel pressure regulator.

 

[Sparky]

Sorry I missed this thread earlier. It makes sense it was the regulator, my old car had a failed regulator and would do that. (different engine, but same idea)