Low fuel pressure will damage injectors 6.0 POWERSTROKE FUEL PRESSURE TESTING AND TIPS

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Bertram Copeland
6 years ago
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1 Low fuel pressure will damage injectors 6.0 POWERSTROKE FUEL PRESSURE TESTING AND TIPS

2 WHAT CAUSES INJECTOR FAILURE This chart is from FORD. As you can see, we need to do our part to ensure the customer gets good service without un-needed repairs. Many repeat repairs can be attributed to improper filter replacement or service.

FUEL SYSTEM DIAGNOSTICS Check regulator and return lines for restriction Check fuel pressure at the test port in the secondary filter housing Flush system ; Replace fuel and filters Bad fuel Sample

3 FUEL SYSTEM DIAGNOSTICS Check regulator and return lines for restriction Check fuel pressure at the test port in the secondary filter housing Flush system ; Replace fuel and filters Bad fuel Sample fuel Inspect replace fuel filters and retest Amp ramp and voltage drop fuel pump and wires Repair wiring or replace fuel pump Check for fuel inlet restriction. Check pressure regulator. Repair restriction or pressure regulator

4 FUEL TEST PORT If fuel pressure drops below 38 psi under heavy load, there is a fuel delivery concern. Always verify fuel pressure under load. Fuel pressure test port F series 4 E series back of each head

5 FUEL PUMP AMPERAGE D/C COUPLE A/C COUPLING 5

6 PRIMARY FILTER Primary filter removed 10 micron filter After fuel is drawn from tank and conditioned it flows to secondary filter 6

7 SECONDARY AND PRIMARY FUEL FILTERS 7

8 SECONDARY FILTER Four micron filter Mounted next to oil filter on top of engine Secondary filter also houses regulator valve Returning excess fuel to return line also incorporates an orifice at the top of housing to bleed any air out of fuel 8

9 INLET RESTRICTION TEST Low fuel pressure and volume could be caused by tank restriction Check inlet side of horizontal fuel conditioning module for a vacuum Tee in vacuum gauge with fuel inlet Five six inches of vacuum maximum Higher than five or six inches of vacuum check fuel inlet line and tank 9

10 FUEL AERATION TEST Remove return line at horizontal fuel control module Install clear hose on return line and run into clean container Operate engine at WOT for a short time and watch for bubbles in clear hose 10

11 WATER DRAIN Located on the side of fuel conditioning module located on drivers side frame rail There is a casting plug on Fuel housing has to be removed to drain water 11

MULTIPLE CYLINDERS SAME SIDE LOW ON POWER?

All 4 cylinders on the bank will have low power or

12 MULTIPLE CYLINDERS SAME SIDE LOW ON POWER? The fuel supply line on the front of both heads has a banjo bolt with a flow valve in it. This valve can restrict with contaminants. All 4 cylinders on the bank will have low power or misfire concerns. To verify the concern, check fuel pressure at the back of the head involved.

13 BAD COMPRESSION RING If this concern has existed for a period of time, keep in mind all 4 injectors on that side of the engine should be replaced. Air can be compressed so the injector gets pounded and does not have the amount of fuel needed to lubricate and remove heat. Copper sealing rings must be replaced any time the injector is removed. They are one time seals only. TIP-PwrBal. Test can find the worst of the bunch for us to Start with Upper fuel o ring Fuel inlet Lower fuel o ring Compression 13

To diagnose this concern just remove the secondary fuel filter. Remove fuel pump voltage feed or fuel pump relay.

14 POOR RUN FUEL PRESSURE OK Multiple cylinder misfire can be caused by one injector allowing compression pressure to bypass the copper injector compression seal and fuel o ring causing severe aeration of the fuel. To diagnose this concern just remove the secondary fuel filter. Remove fuel pump voltage feed or fuel pump relay. Remove the cam or crank sensor wire, crank the engine and look for air bubbles in the fuel. You can remove the left or right fuel line to determine what bank has the concern. But keep in mind it will be the one with the misfires.

FUEL LEAKS INTO THE OIL? Bolts can break and cause a fuel leak. Oil leak Always check the oil level before you service a 6.0 power stroke. If the oil level is too high, suspect fuel leaking into it.

15 FUEL LEAKS INTO THE OIL? Bolts can break and cause a fuel leak. Oil leak Always check the oil level before you service a 6.0 power stroke. If the oil level is too high, suspect fuel leaking into it. Pull the drain plug until the oil stops leaking. Run the fuel pump. If fuel leaks out of the oil drain, you found a problem. Block the fuel flow to one head to isolate what bank the leak is on. Fuel contamination can hurt the turbo shaft and bearings.

Insert a vacuum gauge in the line between the tank and fuel pump inlet.

16 FUEL INLET RESTRICTION OR AIR LEAK Install a clear looped hose in the fuel return line. Hold the engine RPM at a steady Verify there are no air bubbles. Insert a vacuum gauge in the line between the tank and fuel pump inlet. If fuel pressure was low, ensure vacuum stays under 3 inches at idle and does not exceed 7 inches under high RPM and load. If vacuum is high, check for a restricted fuel pickup or line.

17 HFC MODULE NEW DESIGN If you replace the HFC module, you make get a newer design that no longer has the fuel heater. There is a molded hole where the heater went. There is also a replacement harness that removes the electrical plug.

18 NEW HARNESS HAS 3 CONNECTORS 18

19 OLD HARNESS HAD 4 CONNECTORS 19

Fuel System Diagnosis

Fuel System Diagnosis Page 1 of 6 2004 Chevrolet Chevy K Silverado - 4WD Sierra, Silverado (VIN C/K) Service Manual Engine Engine Controls - 6.6L (LLY) Diagnostic Information and Procedures Document ID: 1460257 Fuel System