My #4 fuel injector line cracked spewing diesel. Is it possible that my programmer (Diablo PowerPuck) is spiking the fuel pressure and causing the injector lines to rupture over time?

 

Have you defeated the stock fuel rail pressure release valve? I'm assuming the 5.9 has one like the 6.7 does, and when cranking up rail pressure you have to either shim it to raise the release pressure threshold or just cap it off.

It's entirely possible, although I'd wager there was a defect in your line that was exacerbated by the increased pressure.

If you're blowing out lines, think of the abuse on your nozzles.

 

I've heard of tuners raising psi to the point of cracking injector nozzles, but never the line itself. I'd say it's just a bad line. Either it vibrated against something or the bolts have fallen out for the fuel line clamps.

Jeff.

 

The #1 line was leaking at the fitting which the dealer tightened. A week later I found the #4 fuel line clamps in between the rail and intake and the line was cracked and spewing fuel. The dealer towed/repaired it (free) but unhooked my programmer. When I questioned it, the mechanic told me it was common for the #4 to crack every 30,000 miles or so due to the increased pressure caused by the programmer. Seems farfetched to me but I'm not a mechanic.