ECU failure

[KHorsman]

I have an EJ22  94 in a beach buggy. Engine coughed a few times. Once stopped it would not start. Fuel pump does not activate.   OB1 electronics.

Earthed solenoid and the fuel pump worked, still no start. ECUs are getting very rare so bought a re-conditioned one at great cost. Installed and no change. 

Checked power and earths to the ECU , all OK. Connected green plugs , and pump does not turn on. 

The supplier claims the ECU was tested and OK, but this sounds to me  like an ECU failure.

Can anyone help with any more ideas?

[jonathan909]

By "earthed solenoid" I assume you mean "grounded the coil of the fuel pump relay".  So far, so good.  From where you are, I wouldn't jump directly to "bad ECU".  Let's go back to first principles, and stop me if I get anything wrong.

The initial failure symptom was no fuel, but you know the relay and pump are good, so you changed the ECU, but that didn't solve the problem.  You're reading that as "two bad ECUs", where I read it as "ECU not the problem, because you just swapped in a known-good (according to the supplier) one".  The whole point of the ECU is that it listens to a whole bunch of inputs and drives a whole bunch of outputs.  So I'd be looking at all of the inputs to see which ones need to be satisfied in order for the ECU to want to pump fuel.

 

Edited 10 hours ago by jonathan909

[KHorsman]

Good point. But which other inputs are required?

Harness was modified so that clutch switch , trans switch are bypassed. My main issue is none of the wiring diagrams are correct for my engine. I have just found a manual for an AUS spec 2.2  1994, and the plugs are the same , but the wires are completely different.

[el_freddo]

Have you interrogated the fuel pump relay to ensure it’s working properly? 

How are all the electronics stored in the beach buggy? If the relay is left to atmosphere conditions it could be dirty contacts - in the fuel pump relay and/or the main six pin relay. If the ECU is getting power but the fuel pump is not activating, how are your earth points looking? 

You’ll find your wiring harness diagrams somewhere. Alternatively this is where you now spend the time probing every single wire and recording what it does and where it’s located in the ecu pinout. 

Not fun but could help with future trouble shooting. 

Have you checked for codes with the check engine light? 

Cheers 

Bennie

Edited 6 hours ago by el_freddo

[KHorsman]

Thanks, Bennie, I had no check engine light. The main 6 pin relay was clicking but not tripping.  After tapping it  the fuel pump relay and pump came on and the engine started, Yeh.

I will replace the  relay to help with future reliability.