EDIT: Runs great thanks to 3 forum members that actually know what they are talking about.

 

See what fuel pressure is doing.

 

Stock computer running that 408? Is it possible that, since it is a bigger motor with a bigger fuel demand, the computer is starving it of fuel since it thinks its running a 360? Just a thought...

 

If I keep my foot on the gas it will stay running.

 

Stock computer?


If the fuel pressure is okay, the next step is computer programming. Cheapest/best option is to contact hemifever (apparantly a member here... PM or email him) about a custom tune using an sct tuner for your truck. He will build a tune for your exact motor, and you can load it up into your PCM to run your truck.

 

yeah pretty sure the stock computer wont run that 408. Did you upgrade your injectors by any chance? Ive read on here in other threads about having to do a fuel sync if you pull or change the distributor. Not sure if that would pertain to this but im willing to bet youve had that distributor out. Maybe someone else will chime in on that.

 

Oooh, good thinkin! Yea fuel sync needs set, but ya still need a custom tune to run that motor,

 

Heck ya!!! Thank you. lol. I knew i was learning something from this forum.

 

Stock fuel system will feed a 408, but not the stock injectors and you WILL need a SCT tune to make it work, as said your fuel sync needs to be set, but where you set it depends on your build. +4 is safe.

More info on the build please....And quit trying to run it before you kill it.

Just dropped a 408 in my Dakota this month....412 RWHP

 

Damn.......I want a 408!.....why do you guys keep making ideas pop into my head............