Scenario

Car starts normal. Then dies. Then refuses to fire at all
New ECU put in, starts, then dies again after 5 mins.
ECU checked - new ecu is ok this time
All electrics checked, fuel pump checked, plugs checked, all good

What other things could be causing this?

Sounds like a tricky one......
What car Is It we talking about a rex?

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11.1@125mph

Does it throw any CEL's?

Is the ECU from an AUS spec forrie?

COULD be a problematic pin on the ECU loom - I had problems with a pin on the ECU loom after I removed a Power FC and put Autronic back in. Car wouldn't start, jiggle the loom about abit, car starts... drive abit, go over a bumpy patch, car dies. Turned out to be a loose pin in the ECU loom.

Good luck Joe.

Its an aus spec forrie. ECU is aus spec. Original ECU is confirmed dead, output signals on injectors are fine, but 2 out of the 4 input signals from the injectors on the ECU board is dead. No CELs at all.

With the new ECU we tried, it started for a solid 5 mins. Then died. All wiring has been checked. There's one dodgy looking wire, a yellow one, which wasn't connected to the ECU at all. Not sure what this is for. It does have a sign of being "burnt" out.

The new ecu board has been tested and all signals are running A-ok. Seems to be a problem that may have caused the original ECU to die but touch wood has not affected the new one (yet), touch wood again

Keep throwing some ideas if you can guys.

Appreciate the feedback right now.

Joe, the only wires which were changed for the motec originally in the forrie were for the fuel pump. Maybe check those.

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www.racewars.com.au

Will give that a go. We've given all the wirings a check.

Will give it another once over.

I'm stumped with the original ECU not working but the new one being able to work on connection then failing though.

Walbro pump?

I'd be pointing my finger at that..

On the first failure, the pump was checked, and no issue. Haven't checked it the second time. There's a lot of stuff on the 2nd checklist to go through again at the moment.

Fuel pump controller?