Air is getting into your fuel system, by one of three ways.
The following is found on the 7.3 fuel system, 6.9 will be somewhat different.
1. When was the last time that your return lines were changed? On this subject change the caps and o-rings plus the hose. Especially if you have any leakers or dry
rotten lines.. Oh and don't forget to replace the return line from the filter head to the Number 1 injector, along with the return line from Number 2 injector and the
injector pump....
2. The metal line that runs from the filter head to the injector pump, has two seals called olives 5/16 in size. parts are available from International.
3. Return line valve, located on the fuel filter head, next to the schrader valve, 1/4 hose running from the Number 1 injector to the filter. Should be able to blow thru
one side but not the other, if able to blow through get another one.
Hope this gives you a good start....
