P0091 after engine swap

Well folks. We have success. I have to preface, I'm an electrical engineer. I know my way around a multimeter. I checked against the negative cable to the body of the hpfp and all around it and to the ground connections. All 0 ohms.

Just to be comprehensive (before dumping 400 on a pump) I ran an 8 gauge wire from the ground location next to battery and connected directly to the hpfp (upper bolt). Boom, problem solved. 400 ish idle pumping up to 1600 at high rpm.

Kind of embarrassed. Best guess, the stupid multimeter is garbage.

I plan to now re-run grounds as there's clearly an issue. Really appreciate all the guidance guys!!

 

haha that classic "hpfp ground" strikes again. such a weak spot on our engines and causes some funky issues.

glad you got it sorted.