Ignition Fault

[Fury1630]

Who knows the intricate workings of an OMEX ECU?
I've been having trouble with the Fury not starting & at first it seemed to be a tank issue, then the fuel pump, then possibly stale fuel, but I've found that if I put a circuit tester on the central terminal of the coil pack connector, it lights with ignition, then there's a click from a relay under the dash & the light goes out. Equally, if I switch on the ignition & push the starter, the engine fires & runs perfectly, but if I switch on the ignition & wait for the relay click the engine turns over but won't fire.

I know there's a system to run the fuel pump, then cut it until the engine fires, it's not used on my car, but it seems to be controlling the coil suddenly?

Am I going mad? I guess I need to trace some wires & see what this relay is doing.

[steve m]

What happens if you take the relay out completely? will the engine run ?

[Matth93]

Could it be a immobiliser playing up? I don’t know your system but mine (nodiz) doesn’t have a relay between the coil and ecu

[jeffw]

I'd lay money on it being the fuel pump relay

[ncd]

Hi T,

If you load your map in Map3000/4000 either from a saved copy or by connecting to the ECU you can see what the auxilary outputs are set to. In my rather retro Omex 550 I can only select a single aux output, either fuel pump enable or tacho - mine is set to engage the fuel pump.

Yours is the 600 or 700?

From the 600 manual it doesn't look like you can select the fuel pump or not: 2.13 Fuel Pump: "When power is first given to the ECU it will turn on the fuel pump output for 2 seconds to prime the fuel system. When the ECU sees the engine cranking it will turn on the fuel pump output continuously." and then at the bottom "The power supply relay for the injectors, coil, lambda sensor etc is controlled by the fuel pump output.".

Which makes me wonder if it's not 'seeing the engine crank' and not providing power to the injectors/coil/etc?

Here's the page from the manual:

omex600-ecu-page.png (51.29 KiB) Viewed 3262 times

Cheers,
N

[Fury1630]

Which makes me wonder if it's not 'seeing the engine crank' and not providing power to the injectors/coil/etc?

I've wondered that & it'll be the first thing I check this morning. I've had the dash out of the car & I'm wondering if I've disturbed something.

That wiring diagram is different to the one in my book. I think there must be a new issue as there's no "2.13 Fuel Pump" section at all.

Investigation required.

Thanks all.

[Fury1630]

I'd lay money on it being the fuel pump relay

How much?

[Fury1630]

There's some strangeness going on here - of my own making I'll grant you.

There's two relays behind the dash, one has a fat red (stop me if I'm getting to electronic), a thin red, a green & a Blue / white.

The fat red is permanent live
The thin red is ignition live
The green goes to the coil
The blue / white goes to the ECU where it's earthed with ignition & cut two seconds later

So, as experienced, the engine will run only if it fires within the two seconds. I put a non switched earth in place of the blue / white & the coil stays on & the engine fires.

So you may well ask, why have I got the coil wired to the fuel pump relay?

It's a question I've been asking myself, along with how was it working before? & what's changed to make it not work now.

Just to add to the confusion, next to that relay is another one - not working - aha! I thought, but it's switched by the fuel pump switch on the dash & energises a wire that goes no-where in the engine bay - I think it used to drive the HP pump when that was up front.

So I seem to have fixed the fault without ever knowing what the fault was.

[jeffw]

So I seem to have fixed the fault without ever knowing what the fault was.

Almost as annoying as the fault itself

[Wingco]

Tony, you are a bloody genius, you can fix things with out knowing it !!