Vehicle: 2003 Ford F350 Super Duty, 4WD, V8-6.0L DSL Turbo, Manual Transmission/Transaxle

Mileage: 185,202 miles

Problem: This truck was dropped off at the shop because of hard starting, stalling and lack of power.

Case Details: The shop determined that there was air in the fuel system. After bleeding the air out of the fuel system, the engine would run for about one to three minutes, the fuel system would slowly fill with air and the engine would die.

The technician installed a new fuel module, new filters, new O-rings in the quick connectors and installed a new regulator kit with an upgraded spring. None of those repairs fixed the problem. Next, he removed the fuel tank to inspect and vacuum test it and the fuel lines. He found no issues, but at that point, he was certain the air was coming from the injector side of the fuel system.

The technician removed all the injectors and sent them to the diesel shop for testing. The diesel shop found no problems with the injectors, so he reinstalled them with new seals/washers. But the fuel system aeration issue persisted. At that point, a call went out to an ALLDATA Tech-Assist consultant.

The consultant suggested doing a cylinder power balance test to pinpoint if any one cylinder was the problem and if air was being pulled in by any single injector. The technician did a power balance test and singled out which cylinder dropped out first before the engine died. He removed all four injectors from that bank and carefully inspected the injector cups and his previous work; making sure he didn't double up a copper washer or roll any O-rings. Upon careful inspection, the technician noticed the injector that dropped out of the power balance first had much less soot on the tip than the others (like inspecting spark plug tips to see which one might be misfiring).

Confirmed Repair: The technician replaced all the injectors in that bank to be on the safe side. The engine started and ran perfectly. A good test drive verified the fuel system aeration problem was solved. Fixed!