'96 CD5 won't start?

We've got 2 x CD5s, 1 has the F22B1 engine, the other F22B3. My son called me a week ago and said his car had stopped (F22B3), I asked him to describe how it stopped, after which I said it sounded like the fuel pump, ring the RACT. Bloke turned up, checked it out, diagnosed the fuel pump and organised to have it towed home. I'd done a fuel pump on the other car at similar mileage, so figured it must be common, ordered a pump and replaced it, no difference. Pump primes and cuts out, engine light goes out as it should. Investigating further it looked like the spark may have been a bit week, I put new plugs in it, checked lead resistance, checked coil, cleaned up dizzy posts and rotor, spark is good, no start. I measured voltage at an injector connector while engine was cranking, and best I got was 0.5V, on the other car I get 2.5V. After searching the forum and reading the manual my next point to check is the main relay, then ECU, unless anyone can point me in a direction I haven't considered. After all that, the questions I have is, will a dud relay cause the symptoms I'm having? And can I swap the ECU from the other car, considering they're the same except for the engine type? Any help appreciated.
Cheers,
Mick.

I am assuming there is no engine light appeared on the dash. Have you checked all the fuses, and see if they are alright?
Does the engine crank?
Grounding wires ok? Especially near the fuel injectors.
How many fuel injectors does not have power?

I am not sure if this is the same accord. It about the location of the main relay. This usually can be repaired if it has frozen solder.

https://www.youtube.com/watch?v=38DQ5IVQQ68

I've removed the main relay, solder joints looked good, I desoldered and resoldered anyway. I can hear and feel both relays do what they're supposed to do when the ignition is turned on and the engine is cranked, but no start.

From what you are saying, the reason why the car did not start is because fuel is not getting inside the engine because the fuel injectors did not have power to operate (open/close).
Relay is good, fuel pump is new, all fuses are ok and the grounding wires are ok. Spark is good also.
Engine not flooded?

Ok, so I've swapped the main relay with the other car, it works fine, I've also swapped ECUs, they work fine, in the other car! I've checked ignition timing, it would appear that #1 is firing about 15-20 degrees after TDC, 30-40 degrees after the ignition timing marks have gone passed. I'll do some more checking on the weekend, but I'm suspecting the timing belt may have decided to skip a few teeth.
Are these an interference engine?
If indeed the belt has jumped teeth, is it likely to have bent any valves?
Cheers,
Mick.

Can you please tell me the history of the car? Does it get serviced regularly including timing belt and tensioner?
And what happened just before the car stopped working (any repairs/servicing)?
Last time when I changed the fuel filter inside the fuel tank, I left a little hose that connects the pump to the fuel line. I was a little confused why my car did not want to start.

Timing belt was 1 tooth retarded, it's now running.