Jeff,
There are several things that could be your problem, but the most likely thing is a air leak in your fuel supply line. Have you checked the O-rings on the prefilter for the primary fuel filter, assuming that you are still running the OEM Racor primary fuel filter? If there are any signs of fuel leakage at either end of the prefilter, you have a vacuum leak and need to replace the O-rings.
There are 4 O-rings (2 number 208 and 2 number 114) that seal between the plastic prefilter Racor part number 300200 and the metal housing. However, if there are any cracks in the plastic prefilter, you will need to replace it as well assuming your priming pump still works OK, if not just replace the primary filter with a new one that includes a priming pump.
You can use small amounts of starting fluid on a C12 if you are experienced in working on a diesel engine, but you should never use starting fluid on the smaller Cat engines because they have an intake air heater that can cause an explosion in the intake manifold resulting in dangerous and expensive engine damage. Therefore, since some owners do not understand the difference in engines or the proper procedure, I tell the average owner to not use starting fluid (ether).
Gerald
