1991 240sx Fuel pump shuts off upon car start.

[Lost_In_Translation]

Ok the car works but the fuel pump is powered by a fan relay that the previous owner placed. I tried to reconect the cables back to stock and with the switch on the fuel pump worked fine but as soon as I cranked the car the pump shuts off. When the car shuts off the fuel pump starts again.

The original relay works and the fuse is good but for some reason the ecu isn't getting a signal or something when it turns on.. I read in a old post that if the ecu doesn't detect the rpm signal it will shut the pump off.. could this be my problem? btw my car was changed from auto to manual ( not by me ) thanks for any help.
Modified by Lost_In_Translation at 7:22 PM 8/19/2007

[slipnfall]

Sounds like you have the pump/relay triggered by an Accessory wire. This wire drops out on start to provide all power to the starter/electronics. Easy way to test: pull your starter fuse and crank the key. Pump should not turn off.

[Lost_In_Translation]

Thanks for the reply I'll try this today but I'm not really sure which is the starter fuse. Any other ideas are greatly appreciated.

[Lost_In_Translation]

Please help.. I even followed the FSM procedure for fuel pump problems and it seems fine... the problem is only when I turn the car on...

[Lost_In_Translation]

Bump for help, please..