Hi, Im hoping someone can spot the obvious reason that I have missed trying to get my ’89 TB42 manual SWB to start.

For a while she has backfired on occasion when you came off the pedal and she idled a little rough at times but fuel economy was good as was power. She is fitted with a Petronix ignitor.

Of late the backfire got worse and she started to miss so I decided to give the whole system a good overhaul. I did this in stages as parts arrived but she gradually got worse until she now simply won’t start.

She turns over on the starter.
I have replaced the coil with a flamethrower, removed the resistor, replaced the dissy cap and rotor (not an extended version), replaced the plugs and leads, put in a new mechanical fuel pump and filter, and put an overhaul kit through the carb.

I have confirmed that I am getting spark at all six plugs, have tried powering the Petronix direct from the battery and checked the voltage at the coil so I am pretty sure it is not electrical.
I have confirmed that fuel is getting to the carby and can see fuel being delivered into the carby when the accelerator is depressed.
I have tested compression (cold obviously) which is good and consistent across the cylinders.
I have checked all the vacuum pipes and made up new ones where needed.
I have cleaned the EGR value which rattles correctly.
The needle and float seemed good when I put the kit through the carby and I have tried another carby from an auto which has been sitting around for years.

But still nothing; she cranks but refuses to start and eventually spits fuel back out through the top of the carby. I am now at a bit of a loss what to try next. Any suggestions would be much appreciated.