Can I use the starter to prime a 6.7 Cummins if the lift pump fails?
Technically yes, but it's risky. If the electric lift pump is dead, you can crank the engine in short 10-second bursts https://www.cq-longshine.com/b....logs/how-to-prime-6-

What if my 6.7 Cummins won't prime after several key cycles?
This usually means air is still trapped, or there's a leak. First, check that the fuel filter is tightened properly – hand-tight plus a quarter turn. https://www.cq-longshine.com/b....logs/how-to-prime-6-

Why does the barrel and plunger cause fuel knock when worn?
When the plunger and barrel wear unevenly, injection timing becomes erratic. Fuel may leak past the plunger during the injection stroke, then suddenly release in a burst. https://www.cq-longshine.com/c....ummins-barrel-and-pl

Can I replace just the plunger without replacing the barrel?
No. Cummins barrel and plunger sets are matched and lapped together during manufacturing to clearances within 0.0001 inch (2–3 microns). https://www.cq-longshine.com/c....ummins-barrel-and-pl

How do you know if a barrel and plunger is worn?
Symptoms include:

Hard starting or no start

Erratic idle or surging

Low power under load
https://www.cq-longshine.com/c....ummins-barrel-and-pl