No Spark No Fuel, blown main relay (white one) Bad ECU possibly HElP!

[ZekeTheSneak]

Swapped my m20 into my 318is and theres no spark or fuel, we checked the main relay it was dead so we then checked bypassed the relay (my buddys a UTI graduate) and got the fuel pump to prime but the ECU is still not telling it to ground to turn on the fuel pump and ground the distrib. whats your opinion? he thinks the ecu is dead.

[e30_3I8I]

Are you getting ur idiot lights on when your battery is connected? like a back feed to the system?

[ZekeTheSneak]

which lights? with key on they are all lit up so yes

[ZekeTheSneak]

also ive been reserching for a while now and ive been mainly seeing bad ecu and relay if that helps

[StereoInstaller1]

I think I have a spare 173 laying around I might loan out, and I work in TacoTown

[ZekeTheSneak]

Luke I will call you tomorrow once I'm off at 2. I gotta go to the stealership for a relay anyways

[jlevie]

Is there spark when cranking the engine? No spark and no fuel pump operation suggests a lack of timing data to the DME (no signal from the CPS), no power or START signal to the DME, or a bad DME. Since this is a transplant, run through what's below to find the problem.

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.

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 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 0.040"), 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 batter 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.

[StereoInstaller1]

I work 10 to 7, then have pool, plus I gotta find the damn thing in the avalanche that is my garage right now.

In other words, I might not have it today...

[ZekeTheSneak]

thanks luke and jlevie i will be going over the c101 plug with a buddy making sure the connections are proper luke said to do this first since it is a transplant, from there i will begin troubleshooting some more. thanks for the quick response and all of the info that my buddy will understand much more then i will when it comes to wiring :)

Zeke

[StereoInstaller1]

'89 motor/harness into an M42 car. I bet only a couple wires are different, but there will be differences!

Zeke, what this means is you need to document so the next poor fool who tries this will get some love.

[ZekeTheSneak]

will do luke, im sure i will be calling you around 4 or 5 today haha. Yah i have not found a single link on swapping an m20 into a 318 its like im the first or somthing. oh all the chasis wires are different colors so tracing wiring diagrams will be fun

[ZekeTheSneak]

does no one have an 89 m20 c101 pinout? i have looked and looked.

[e30_3I8I]

did u connect the coil wire to a ground or did u accidently connect it to the positive on the battery ?

[Kershaw]

jlevie brought the knowledge. im so impressed that he can just write that up off the top of his head.

[StereoInstaller1]

jlevie brought the knowledge. im so impressed that he can just write that up off the top of his head.

Yeah, no shit!

I went to Zekes house and got the thing running in about 5 minutes: CPS and CIL were reversed...OOPSIE!