Proper vacuum routing - 454 EGR/EVRV solenoid

[Luke_P]

I'm diagnosing a code 32 and one of my checks was of the vacuum lines and boots. In doing so, I referenced the FSM to ensure it's all hooked up correctly. The truck is newish to me, so the first time I look at any system I like to start with the basics.

Anyhow, the two illustrations on this in the FSM seem to contradict each other. On my solenoid, the larger of the two nipples is on top, and currently hooked up to the TBI. This matches the overall diagram, figure 9-10. However, figure 9-16 clearly shows the larger nipple going to the EGR valve, opposite what I have. The solenoid will allow air through if I pull a vacuum through the larger nipple when the solenoid electrical connector is unplugged, which should indicate a failing solenoid.

Looking around online I have seen it both ways. Does anyone know the correct answer here?

This is a 1989 K3500 with the 7.4l/454

Thank you!
Luke

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[packer0440]

If you have the original vacuum lines, it’s impossible to mix them up; the sizes are different to ensure you get them on the correct way. In the event you don’t, the top port on the EVRV should be connected to the TBI, the bottom one should go to the EGR valve

 

[Luke_P]

I verified my hoses were hooked up as stated above. And to close this story, I pulled vacuum per the troubleshooting guidelines in the service manual and it showed the solenoid valve was bad. I replaced it with new and no longer get a trouble code.