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JFP in PA · 08-02-2023, 02:09 PM

I would start by connecting a fuel pressure test gauge to the Schrader valve test port on the fuel line and testing for both pressure and fuel deliver rates. If either is off spec, I would pull the fuel filter and replace it, then test pressure and deliver again. If it still fails, the pump itself is bad. Whenever we do a pump on one of the early 986's with and external filter, we always replace the filter along with the pump, so you would already have a new filter in place. Misfires are common when the system goes way lean.

08-02-2023, 02:09 PM	#8
JFP in PA Registered User Join Date: Feb 2005 Location: It's a kind of magic..... Posts: 6,521	I would start by connecting a fuel pressure test gauge to the Schrader valve test port on the fuel line and testing for both pressure and fuel deliver rates. If either is off spec, I would pull the fuel filter and replace it, then test pressure and deliver again. If it still fails, the pump itself is bad. Whenever we do a pump on one of the early 986's with and external filter, we always replace the filter along with the pump, so you would already have a new filter in place. Misfires are common when the system goes way lean. __________________ “Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein