Hey y'all!

So, I'm working on my new toy, a 1999 Government K2500 Suburban... I brought it home and it ran like new during the test drive and getting it off the trailer, and now I cant get it to start for the life of me.

When I crank it, it sounds like its ALMOST going to start, but never does. As soon as I let off the key, it makes a strange "PHOOMP" noise that literally rocks the entire truck. What should I do, guys?

I've already installed a new fuel pump...

Thanks in advance...

 

Is the check engine light on? If so check the code. This will lead you in the right direction.

 

No, its not throwing any codes. ANY HELP IS APPRECIATED!

 

I would check the ignition timing and make sure that it is getting a strong spark at the plugs.

 

I'd disconnect the battery, and go have a cup of coffee, or a nap, and the come back, reconnect the battery, and see if it starts. I have a 5.7 in a van that for all indications was not getting any spark. It sat for 6 weeks while I dealt with other issues. Today I put the battery back in it(had removed battery to use it for a jumper on another project) just for curiosity, tried to start it, and it started right up. Maybe the computer needed to be reset? I dunno, but I'd sure try it.