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Q: No fuel to the fuel rails. Replaced battery (it was bad).. I'm trying to determine if the FPDM is bad or the fuel pump is bad

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I couldn't find any pin layouts with correct voltages for the different color coded wires and pins... I am going by color coded wires because I don't know which pin is pin #1 (as I said I can't find any schematics or layouts for the pins and their proper values) So I made some measurements from ground to pins with the FPDM completely disconnected from the connector to the fuel pump. I haven't yet plugged it into the fuel pump and made measurements while its in circuit. It is putting out voltages and some seem odd as there is a obvious 12 VDC line that isn't reaching 12VDC. (Yellow / White Stripe) that reads 11.28 VDC and when i attempt to start while engine is turning over the voltage at this line (Yellow / White Stripe wire) drops to 10VDC... I would like to know if you can find a pin layout which pins or wires by color code go to the actual pump so I can put 12VDC directly to the pump and see if it builds pressure. Thank you for your time. FPDM part# YF3F-9D372-AA

pump part# ?

My car has 123948 miles.
My car has an automatic transmission.

A: Hi there, From what you have described in ...

Hi there, From what you have described in testing the fuel pump circuit, it appears you on the right track. The voltage drop you are seeing, key on engine off and engine cranking, would be considered normal. The load placed on the battery, in both situations. Easiest way to identify the fuel pump voltage feed wire. Test the circuit while an assistant turns key to the on position first, then while the engine is cranking. What you should see is, key on engine off (voltage supplied for (2) seconds; initialization), key on engine cranking (voltage supplied steady). Don’t forget about the ground circuit for the fuel pump (check for continuity with your ohmmeter / should be near zero). If, your circuit test passes. The fuel pump failure, is likely. I recommend having the lack of fuel pump pressure be diagnosed and repaired by a certified technician from YourMechanic.

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