Truck still will not start

Tiny
RONI0788
  • MEMBER
  • 2003 GMC SONOMA
  • 4.3L
  • 6 CYL
  • AUTOMATIC
  • 120,000 MILES
Parts replaced this weekend:
I replaced distributor cap, fuel filter, battery.

Parts replaced last year:
Crankshaft sensor.
Fuel filter.
Sunday, February 18th, 2018 AT 4:24 PM

4 Replies

Tiny
HARRY P
  • MECHANIC
  • 2,293 POSTS
Have you checked the fuel pressure? These engines need about 60psi of pressure to start. Failed fuel pumps are ridiculously common on them, as well. How do I know that? I have had two Blazers and between them I have done three fuel pumps.

So start with the simple test. Simply lay under the truck or near to the tank as you can and have someone turn the key on, but not crank the engine. Listen for a humming sound. If you do not hear it, then the pump is not running for some reason or another (fuse, relay, or pump). If you hear it, but it is not a smooth hum, but more of a train wreck sound complete with grinding, bad pump.

If it sounds right, then you will need to get your hands on a fuel pressure tester. You can borrow one from Auto Zone/Advance Auto.

Here is a general how-to-guide.
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Sunday, February 18th, 2018 AT 7:05 PM
Tiny
RONI0788
  • MEMBER
  • 5 POSTS
I replaced fuel pump last year as well.
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Monday, February 19th, 2018 AT 5:39 AM
Tiny
RENEE L
  • ADMIN
  • 1,257 POSTS
Hello RONI0788@GMAIL.COM,

Here is a link to the guide HEYMAN1104 referred to in his post:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

It has step by step instructions and pictures explaining the process of checking the fuel system pressure, regulator and fuel pump in less than fifteen minutes.

If you need further assistance please come back to the site we are always happy to help.

Kindest regards,

Renee
Admin
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Monday, February 19th, 2018 AT 2:15 PM
Tiny
HARRY P
  • MECHANIC
  • 2,293 POSTS
Sorry I meant to get that link in there. Thanks Renee. As far as the pump, if you bought an aftermarket pump, like from AutoZone or Advance Auto, they are not good for these trucks. I did mine in my current Blazer, and it quit working in about a year and a half and 30,000 miles. They are well known for failing quickly. The pump I have now (warranty replacement from Advance Auto) does not hold pressure after turning the engine off, requiring me to prime the system just about every time I start it. It was like that right out of the box, and Advance Auto refused to replace it again. So, basically, I would still go ahead and check the pressure. Less than 60psi with the key switched on will not do it.
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Monday, February 19th, 2018 AT 6:19 PM

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