after the filter is bled and the engine is operated for 15 to 20 minutes at a fairly high speed. No leak is
indicated if the filter shell is full when loosened from its cover. If the filter shell is only partly full, an air leak is
FUEL LEAK DETECTION
Always check the fuel system for leaks after injector or fuel pipe replacement and any time the fuel connections
under the rocker cover are suspected of leaking. Failure to correct a serious fuel leak in this area can lead to
dilution of the lube oil and bearing and/or cylinder kit damage.
Prime and Purge
Prime and/or purge the engine fuel system before starting the fuel leak check. Prime the system by blocking or
disconnecting the line from the fuel pump, then apply fuel under pressure (60-80 psi or 413-552 kPa) to the
inlet of the secondary filter. If the system is to be purged of air as well, allow the fuel to flow freely from the
fuel return line until a solid stream without air bubbles is observed.
Check for Leaks
Use one of the following methods to check for leaks.
1. Method 1: Use when the engine has been operating 20-30 minutes.
After operating the engine, shut it off and remove the rocker covers. Inspect the lube oil puddles that normally
form where the fuel connectors join the cylinder head and where the fuel pipes join the fuel pipe nuts.
If there is any leakage at these connections, the lube oil puddles will be smaller or thinner than the puddles on
the connectors that are not leaking.
Disassemble, inspect and correct, or replace the suspect part (connector washer, connector, injector, or jumper
line). Test and reinspect.
2. Method 2: Use when the engine is not operating, such as during or after repairs.
Remove the rocker covers. Pour lube oil over all fuel pipes and connectors which would normally be splashed
with oil during engine operation. This will cause oil puddles to form at the joining surfaces as mentioned in
Block off the fuel return line and disconnect the fuel pump supply line at the secondary filter. Install a pressure
gage in the filter adaptor, then apply 60-80 psi (413-553 kPa) fuel to the outlet side of the secondary filter with
the inlets plugged. Severe leaks will show up immediately. Minor leaks caused by nicks or burrs on sealing
surfaces will take longer to appear. After maintaining 40-80 psi (276-552 kPa) for 20 to 30 minutes, a careful
puddle inspection should reveal any suspect connectors. Inspect and repair or replace connectors as
necessary. Test and reinspect (see note).
3. Method 3: Use while the engine is operating at 400-600 rpm.
Apply an outside fuel source capable of 60-80 psi (413-552 kPa) to the outlet side of the secondary filter. Pour
lube oil over jumper lines and connectors so that oil puddles form where lines and connectors meet. Install a
valve and a pressure gage in the fuel return line. With the engine idling, close the valve enough to raise the
engine fuel pressure to 70 psi