Crank not start?

FIREMAN5000

MEMBER
2003 GMC YUKON
6.0L
V8
4WD
AUTOMATIC
265,000 MILES

The vehicle was running fine when I arrived at my destination, I was there for 15 minutes and went to start the vehicle and it acted as if it was out of gas, crank but no start. Checked pressure on the fuel rail and got nothing. So replaced the fuel pump and the inline fuel filter. Same problem cranks but no start. Checked fuses and relays all good, couldn't hear the fuel pump engage when the key was in the start position. Sprayed a shot of starting fluid into throttle body in ran for a few seconds and then off. Fuel pump only gets power when in cranking mode. I thought it might be anti-theft, tried resetting that but to no avail. Don't know where to go from here.

Sunday, December 4th, 2022 AT 11:45 PM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,176 POSTS

Hi,

If we are not getting power to the fuel pump, let's narrow things down. First, the PCM B fuse in the under-hood fuse box is the power supply for the pump. I realize you checked fuses, but did you confirm there is power to and from it? If not, do that.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Next, how was the relay tested? There are two power supplies that need to be present at the relay. Have you checked for power? Also, if you remove the relay and locate pins 30 and 87 on the relay plastic housing, and then place a jumper wire between the two connectors where those pins connect in the relay box, does the fuel pump turn on?

Here is a link that explains how to test a relay and how it works:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know.

Joe

See pic below.

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