XJS 4.0L AJ16 No Fuel getting to the Injectors when Cranking Engine

1995 XJS 4.0L AJ16 engine No Fuel getting to the Injectors when Cranking what is it that sends a Signal to the Fuel Pump?

I think the CPS is OK and can hear the Fuel Pump turning on for a few seconds every time I turn the Key but the pump won’t run consistently no fuel coming to the Fuel Rail

Any Ideas?

Quick and dirty test for the CPS is the rev counter registering <>200rpm

Yes Robin, Rev Counter is registering 200 rpm

Thst may sound like car alarm or immobiliser if you have one. Priming of the fuel pump is normal, the rest is triggered by ECU with CPS. Unless there is a security device interrupting it. Are you sure there is no fuel getting into the injectors or injector pulses are not present? Easy to check with LED bulb…

On the passengers side you have a switch that disables the fuel pump if it sets off an accelerometer. Someone likely slapped into it. Press the button, and you might have fuel again!


No Fuel coming through

Hi that was the first thing that I checked

How many miles do you have on the fuel pump?

When was the last time the fuel filter was replaced?

Fuel Pump replaced 6 months ago and the Car was in regular use

There is no option to have no fuel in the fuel rail if your pump is running (in the right direction) and the tank has some petrol left.

  1. Check if your hardlines below the car are not bent by skilled workshop technician placing the jack under those.
  2. Do yourself a favour and assemble two wires with spade/crocodile connectors - allowing you to switch the pump straight to the battery (pump will be running all the time for the time of experiment). Pin up to the tank connectors as your pump is inbuilt.
  3. Check if you have fuel in the tank (silly but possible if your sender is jammed)

If hard-wired pump will make your engine up and running - the problem lays somewhere between the CPS and ECU or ECU itself. From there you can check every relay on the way and ignition barrel itself…
Priming is automatic (on power-up - the sound of your pump for few seconds), then - depends on ECU.

You haven’t answered if you have alarm/immo installed…

If there is no difference with hard-wired fuel pump - you have internal blockage in the system - imundo the fuel line to the fuel rail and place it in the bucket. Then turn the ignition to confirm it (no fuel running = blockage)

My 94 had a similar problem for a six month span.
I had to hot wire the pumps to the battery.
Occasionally forgot to disconnect hot wire when parked causing a dead battery.
All the diagnostics I ran came up ok except power to the pumps.
Finally found a blown fuse going to the heated O2 sensor.
Once fuse was replaced and the car ran perfectly until car was sold.

Hi XJS Banger

You could be right!

It could be the immobiliser but haven’t had time to check that yet though something I never thought of so Thanks for that