- In-Tank - to 03-19-93 Alleged fuel pump failures can often be traced to a faulty fuel pressure regulator instead of (or in addition to) the pump itself. To avoid unnecessary warranty returns and comebacks, it is strongly recommended testing (and, if in doubt, replacing) the fuel pressure regulator before considering the diagnosis of a faulty fuel pump to be complete and correct. May also require fuel pump insulator # 31117-23000 or 23010. - In-Tank Alleged fuel pump failures can often be traced to a faulty fuel pressure regulator instead of (or in addition to) the pump itself. To avoid unnecessary warranty returns and comebacks, it is strongly recommended testing (and, if in doubt, replacing) the fuel pressure regulator before considering the diagnosis of a faulty fuel pump to be complete and correct. May also require fuel pump insulator # 31117-23000 or 23010. -