Not starting in the mornings, or when it is cold

JARPOON

MEMBER
2008 CHEVROLET SILVERADO
5.3L
150,000 MILES

I’ve been having issues with my fuel pump, I replaced the fuel pump and it worked perfect for about a week and now it’s again not starting in the mornings, or when it’s cold. Once it starts it works fine, no bogging or anything. I looked at the fuse box and realized there is no fuel pump relay at all. I’m going to get a new one and put it in, will this fix the faulty fuel pump problem?

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,779 POSTS

Hi,

The relay is located in the under hood fuse / relay box. I attached a picture below and highlighted it.

Now, when it doesn't start, that could be a coupled different causes and may or may not be related to the fuel pump. By chance, do you have a live data scanner? If so, I need you to check the engine coolant temperature sensor reading when this happens. Also, I will need to know the outside temp when tested.

Next, when it fails to start, I would check fuel pressure so we can determine if that is an issue.

One last question, When it finally starts, is there black smoke from the exhaust?

Let me know. Also, here is a link that explains in general how to test fuel pressure:

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

Here are the manufacturer's specs for pressure:

2008 Chevy Truck Silverado 1500 2WD V8-5.3L
Pressure, Vacuum and Temperature
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Specifications Pressure, Vacuum and Temperature
PRESSURE, VACUUM AND TEMPERATURE
Fuel Pressure (Key ON, Engine OFF) .................... 345-414 kPa (50-60 psi)

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Let me know what you find.

Joe

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