LS 400 V8-4.0L (1UZ-FE) (1990)
Left Side Fuel Line
- Remove union bolt from rear of left side fuel rail.
- Install additional union and gauge to fuel rail, leaving original line intact.
- Reconnect battery terminal.
Installing Jumper
- Install jumper wire between check connector terminals +B and FP.
- Turn ignition on and check fuel pressure.
Desired -
38 to 44 psi (265 to 304 kPa)
- Remove jumper wire.
- Start engine.
- Disconnect and plug pressure regulator vacuum hose.
- Check fuel pressure.
Desired -
38 to 44 psi (265 to 304 kPa)
- Reconnect vacuum hose.
- Check fuel pressure.
Desired -
33 to 37 psi (226 to 265 kPa)
- If pressure is incorrect, or did not change, check for available vacuum at regulator. If vacuum is present, replace regulator.
- Stop engine.
- Check fuel pressure 5 minutes after engine shut-off.
Desired -
Above 21 psi (147 kPa)
- If pressure does not hold, block return line and repressurize system by installing jumper wire and turning on ignition for a few seconds.
- If pressure now holds, replace pressure regulator.
- If pressure still does not hold, replace fuel pump.