Fuel pump will not Prime?
 

I got finished a installing a new motor a few weeks ago went to start it this weekend when I noticed the fuel pump will not prime unless power is connected directly to it. Even once the pump is connected the car cranks very slowly but wont start. I tried replacing the relay and check all the grounds and even changed the battery still no luck. Any ideas?

https://drive.google.com/open?id=0Bz...1ZBYTVYdXQwQWc - Errors/codes that are showing on Motec

https://drive.google.com/open?id=0Bz...TNmQ2VwNTFvNDA

https://drive.google.com/openid=0Bz3...U9pa1lacWpCdVE

https://drive.google.com/open?id=0Bz...kRYYkNkdkFGZDA

https://drive.google.com/open?id=0Bz...XZpT1cyZHFMYjA

Loose hose/fitting sucking air someplace? Connecting directly may be bypassing a relay or sensor that won't let it pump unless there is fuel pressure and although you are forcing it to pump it is still sucking some air preventing the proper build up in the rails.
Wild guess but I have had fuel pumps that would not draw due to air leaks before.

Which fuel pump are you talking about ...... the one in the gas tank or the HPFP ....??


humfrz

Gas tank

hmmm.......have you taken the pump out and inspected/tested it .. ??

Under a normal connection, is power getting to the pump..??


humfrz

He said it runs when he connects to it directly.

What's the deal with the motec? Were you running with it before you swapped the engine?

The motec was installed on the car with the old motor.

You're running the Motec for an FA20? The previous motor was also an FA20? The car ran perfect before with the Motec?

There is a pump "controller" that the Motec would need to control in order for the in tank fuel pump to work. The package provided by Pure Automotive for 2JZ/LSx swaps provides the connections and software to control the OEM pump "controller". Other ECU swap solutions do not provide for using the OEM pump controller, so people need to bypass that controller in order to be able to use the OEM pump. Just a thought.

I am running a plug n play motec for fa20. Old motor was fa20 and new motor is also fa20. Car ran fine before with the motec.

You're going to probably need to try and trace the cable for continuity, maybe the cable got torn/cut somewhere along the way while replacing the motor?

Yeah, Bryan, I'm thinking the same thing. Refer to the OEM wiring diagrams. You're lucky those apply with the P&P unit.

AHHHHH!!! I AM HAVING THE EXACT SAME PROBLEM. Motec M150 PnP FA20. Car ran great during tuning the new built motor. Get home and it dies. Motec shows the same fuel pump off voltage. Pump checks out fine with 12v+ but will not prime with ignition on or during cranking. Im pulling my hair.

Did you ever find the smoking gun? Please say yes.

Found my issue. It was the DI controller not grounding properly to the motor.