Am not sure anymore what should happen or not if you disconnect a pump, but did his #2 pump not run for 2 seconds on ignition on?

 

I am not sure if he tried that. I am dealing with an identical pump #2 problem (without the P1646) and mine does not run.

 

On my car, and another early 2001, there wasn't any error code as well when the pump didn't function. Iirc on my car the relay wasn't seated well, on the early 2001 car the pump itself was dead.

 

Mine is also an early build 2001 (build date 7/2000).

 

If the relay Contact Connection was poor but the Coil Connection was OK, there would be no error Code.

I would expect that there would be no difference between the 2000 and 2001. They would both monitor the current flow in the Coil Circuit to detect a open circuit.

 

Manufacture date was 05/2011, does that help in deterimining if the P1646 is for the 02 sensor or the Fuel Pump?

Thank you

 

The fact that you got P1671 when you pulled relay #2 all but proves P1646 is the O2 sensor.

But I still think you ALSO have a secondary fuel pump (not relay, not ECU) problem also that generates no codes.

 

I have a similar problem. i have duel fuel pumps. I dont' know which is #1 and which is #2. I found a fuel pump relay in the trunk fusebox, but I don't know if that is for pump #1 or pump #2. does anyone know if there are separate relays for each pump? The relay i found is working correctly. I believe my problem is with fuel pump #2. I understand that one primes the system and takes over after 3000 rpm. My car doesnt have fuel in the rail. Last time it ran, it wouldn't accelerate over 3000 rpm. I bought a pump but i don't want to replace the wrong one. So im trying to determine which is pump #1 and pump #2. Does anyone know???

thanks,

Jaglady03

 

Welcome! What year is your car and is it an XK8 or XKR? The 3000 RPM limit is often imposed by the ECM due to other faults unrelated to the fuel pump.

 

@ Jaguarlady03 - due to the job, do yourself a favour and change both pumps - you don't want to do it all again in a few months if the other pump goes bad...