fuel pump drops to 6 volts?

[stylingtwagon]

everything was fine with bp swap for 1 year all the sudden i pulled old 91 bp and installed 95 bp and im only gettin bettween 3 and 6 volts at fuel pump no fuel to fuel rail so i sprayed carb cleaner in intake and it started . so my buddy came over put a volt meter on clip goin to fuel pump and not enought volts to make fuel pump run so i installed bp26 ecu and got the same thing and the fuses are good how could this happen could the relay just all the sudden drop the voltage to 6 volts or less it wont even make the fuel pump do anythingf it was fine before the swap . and i checked the fuel pump at the batt and it spit fuel . i even played with the fuel cutoff switch and its fine ? my batt was dead for one day i just charged it but that was fine when i first did it . any idaes ? probably chek relay ? huh

[stylingtwagon]

check out my bpt wagon work log for more info i probably should have put this there but i need info fast .

[stylingtwagon]

bad ground in engine compartmet possable mabye i changed all the grounds to go on the bracket that holds the cluth line above the tranny ?

[yunvmyegt]

i dunno if that would matter much unless thats not a good ground, you got a digital power probe ? id go right to the plug goin to the fuel pump and see what it needs more power or more ground...

[stylingtwagon]

no never heard of it

[yunvmyegt]

get a diagram and a dvom and start at the plug check your power and ground back there, then follow the wires back and figure out where it looses voltage at. i just use the digital power probe cause its easier ,you can get a few diff style pretty cheap i use mine all the time at work.....

[Lex]

First thing, the voltage at the pump with the pump UNPLUGGED. If you see 12 volts between the ground and power line at the pump with it unplugged, and only 6 with it plugged in, I would check/swap out the pump relay sitting next to the ECU.

Also check the resistance between the pump ground and chassis with a multimeter. You should not see anything more than ~3 ohms if the ground is good.

[stylingtwagon]

it was pluged it at first but i just relized i was getting power only from sending unit not main power to pump ill try jumping the relay and better grounds.

[stylingtwagon]

ok now im pissed i changed the relay for the fuel pump and still nothing
i also saw the check engine light is not coming on with the ignition on what an this be

[yunvmyegt]

not sure if its gtr only but i dont think the cel is fuctional anymore, or turns into something else....

[stylingtwagon]

whats a cel , and have u guys heard of a fuell pump diode in the cabin fuse box . is there any ground in the engine compartment or any other wires that are affected by pulling the motor in and out that wolud make this happen ?

[yunvmyegt]

cel, check engine light... isnt the diode near the fuel pump connector? i havent looked in a while...

[yunvmyegt]

ok do you have 12v on the blk/pink from the fuel pump relay, at the relay? do you have 12v into tho relay? that goes to the 30 amp fuel injection fuse in the engine bay. you need to make sure theres even 12v in front b4 you assume its grounds in back.... the whole cars a ground even tho some spots can be better then others....

[Lex]

the light green wire is what triggers the relay to turn on. Ensure that it's being triggered when the car is cranking. Better yet, short it to ground and you should hear the pump turn on.

[stylingtwagon]

ok so the light green wire to ground and it should turn on ? what wires are what to the relay what wires should be what with volt meter?