Hi everyone, I am a newbie here so thanks for having me. I recently started having this problem on my 6.5 diesel tahoe which isn't petfect to start but this is a first for it.... I also believe I caused this issue. The other day I was running late to a meeting and jumped in the truck without letting the wait to start light come on and it kept cranking and didn't start, let it sit a second and tried a couple more times and it started(btw I just got a new gas vehicle and wasn't even thinking about diesel and glow plugs when I cranked it). Ever since that day it runs and drives like it always did but now every morning after wait to start sequence it doesn't Fire right up like it use to... Now it's two tries. The lift pump can be heard clicking as usual so idk if it's air or clogged fuel filter. Any thoughts would be greatly appreciated as I am a broke hands on but not a mechanic kind of guy. Thank you

 

Open the t - valve while the truck is running to verify the lift pump is working. Just hearing it run doesn't necessarily mean it's working or pumping at full capacity.

If you have never put glow plugs in the truck I'd recommend testing them and making sure they all are getting power.

 

Thank you very much for your fast response... I will do what you said. I also appreciate feedback on lift pump as I believe it is pretty original looking and was going to change it just by the look of it. The glow plugs were done about 3 months ago along with new starter, batteries and water pump