89 325is no spark, no fuel

[turbodiesel]

When the key is turned on, no fuel pump comes on. Cranks but no spark, no fuel. Tested the ECU connector using the Bentley manual and got the main relay and fuel pump relay to work, but when the ECU is plugged in, nothing happens. Everything tests fine with the connector. Grounds appear to be OK. Swapped ECU's with a known good one, same thing. Ignition switch?? I'm stumped.. any ideas???

[Killacortes]

crank position sensor. if its bad it wont turn the fuel pump on

[Ether-D]

Yep, I just had a very similar problem. Crank sensor solved it. When I got the old one out, it had been chewed on by the water pump pulley about 15 times. Mine was also really loose and sloppy where the wire exits the actual sensor body as well. I got the sensor for $38 shipped on ebay.

You may be able to get it to limp home by rerouting the crank sensor wire to the top of the motor (if it's a chewed wire). It worked for me for a bit.

[turbodiesel]

Already swapped CKP's.

[jlevie]

Understand that the fuel pump is controlled by the DME and only runs when the DME sees timing data from a rotating engine. No spark and no fuel will be:

No timing data to the DME
A DME power or ground problem
No START signal to the DME
A bad DME

Below is a set of diagnostic steps that may help.


For the engine to run the following conditions must be met:

Power on DME pins:
27 Start Input
18 Un-switched Power input
37 Power Input from Main Relay

Ground on DME pins 2, 14, 19, 24

Timing data from the CPS on DME pins 47 & 48 from a rotating engine

To have spark power must be present at the coil positive and ground pulses
from the DME's pin 1 must reach the coil negative. Power to the coil is
controlled by the ignition switch via C101. When checking for spark, use the
output lead from the coil to eliminate the distributor, rotor and plug wires.

To have injector firing power must be present at each injector and ground
pulses from the DME's pin 16 (Bank1) and pin 17 (Bank2) must reach the
respective injector bank. Note that the injectors are wired as two banks of
three. With cylinder 1,3,5 being bank 1 and 2,4,6 being bank 2. Power to the
injectors is controlled by the main relay. Injector firing is best checked
with a noid light.

The fuel pump relay must have power on pin 86 (relay coil) from the main relay
output (pin 87) and power on pin 30. The DME will ground pin 85 to turn on the
relay and power the pump(s) via pin 87. Of the above, only the fuel pump power
is fused. So if the there's power at pin 87, but not at the pump, check fuse
11.

The main relay and DME pin 18 receive power from the smaller of the two wires
that connect to the battery's positive terminal. That wire incorporates an
in-line fuse. When the DME is presented with a start signal, it grounds the
main relay pin 85 and furnishes power to the fuel pump relay, injectors, and
DME.

Troubleshooting:

Disconnect the battery and the DME cable. Then:

1) Disconnect the coil negative and check continuity from that connector to
DME pin 1. Also verify that from DME pin 1 to ground is an open circuit.

2) Check the resistance across DME 47 & 48, which should be 500-560 ohms. If
the CPS is dismounted, the resistance can be seen to change from about 500 to
540-560 ohms when a ferrous object is brought to the face of the
sensor. Neither pin should be grounded.

3) Check for continuity from DME 36 to main relay 85 and from DME 3 to fuel
pump relay 85.

Reconnect the coil, remount the CPS (air gap should be 1mm), plug the
relays back in, reconnect the DME, and connect the battery. Then do the
following checks:

1) With the key off, verify that power is present at DME pin 18 and main relay
86 & 30.

2) With the key on, verify that power is present at DME pin 27 and pin
18. Power to pin 18 is from the main relay and there should be power to the
injectors and fuel pump relay.

3) With the key on, verify that no voltage is present at the DME grounds (2,
14, 19, 24).

4) Verify that power is present at the coil positive and at fuel pump relay
pin 30. Those get switched power from the ignition switch via C101.

The engine will start and run (if poorly) with only those connections to the
DME in place. The other signals from Cylinder ID, AFM, temp sensor, etc., are
necessary for proper operation. But they won't prevent the engine from firing.

IMPORTANT:

A power check means seeing a voltage within about a tenth of a volt of what
you measure across the battery terminals, which should be at least 12.6v on a
charged battery.

A continuity check means seeing less that 1 ohm of resistance.

An open circuit means seeing a resistance of at least 100k ohms.

A good quality auto-ranging digital multimeter will make these tests much
easier.

[turbodiesel]

There is no voltage at pin 27 with the ignition on. What would cause that.

[Ceeker]

did you by chance jump any positive lead with a negative lead while the car had power? you may have blown the in line 50amp fuse which is located about 1 foot up the positive lead from the battery terminal. Do a stomp test on the pedal to see what code the dash gives you.