If you are making Biodiesel (I assume that is what you ment by "making your own fuel) is that true?

If so -have you changed the orginal fuel lines? Biodiesel will turn the 1985 vintage fuel lines to mush pretty quick and/or degrade the fuel lines enough to allow an air leak.

Common problem-you will need to replace the fuel lines with something compatable with biodiesel.

.Remember that lye & methonal in biodiesel still has the same chemecial properties not good for 1985-era rubber.

Another air culprit is the primer pump-it too can leak in air if damaged or worn

Another good/inexpensive thing is to replace all your crush washers around the filter and primer pump. they can also cause you to loose and not maintain your prime.