Static Pressure at Fuel Rail

[greywolf]

Non Toyota question, but thought a bit of input in general.

What sort of static pressure should I be seeing when the key is set to ignition, but not cranking over. Suspected my fuel pump, but it's not pumping at all unless the engine is cranking.

[CHB]

40-43psi if you are running port injection.

[oldcorollas]

not all fuel systems "pre-pressurise" the rail for a few seconds when you turn key to ON.
some only start pumping during START....

[greywolf]

Thanks oldcorolla, so maybe it's just a restriction in the line, since I'm getting sweet FA pressure even when starting.

[greywolf]

After some more careful investigation tonight, it turns out I'm only getting about 10V at the pump. So I'm off in search of the fuel pump relay, but without a wiring diagram it's bloody hard going.

[renxun]

i wire them direct .... but.. with a relay of course... the moment i turn my key to on, the pump starts pumping.

[JustCallMeOrlando]

i wire them direct .... but.. with a relay of course... the moment i turn my key to on, the pump starts pumping.

It's good that you're using a relay, but the reason all factory ECU's use the circuit opening relay is so the fuel pump stops when the engine does, i.e. an accident

I had a similar problem with voltage at the pump, it was fine at the relay itself, but a good few volts down at the pump. I got some nice new wiring and replaced the stuff to the pump and now have much less of a drop.

[renxun]

bro ... i had this problem similar to yours recently and after a good check, it seems the grounding for the fuel pump is not efficient enough. since my battery had been relocated to rear, i just wire them direct to the battery negative terminal. my pump run cooler and from the sound it seems faster then before

[greywolf]

I'll try re-earthing at the rear of the vehicle, see what happens.