Kr won't start help please

Another kr problem , finished building my caddy and seemed to of found all the running issues but hadn’t , took it for mot on Saturday started fine drove to mot 10 miles away got there and wouldn’t start ,it turns over ,has fuel , thought it was coil but changed that for new one and still nothing,gone through it can’t seem to find out what it is , will bump start and run fine but as soon as turned off won’t fire again , help me please 

Are you saying it will start every time you bump it but won't start while cranking?

Yes will bump start and run but just cranks when you turn key doesn't fire or run

Have you checked what voltage you have at the + side of the coil with just the ignition on and again while cranking. You should have 12v or there about. How old is the caddy and I take it it's convention. The reason I ask is the older ones had a resistor wire going to the coil which dropped the voltage down.

It's a 89 and so is engine ,checked voltages all seem ok ,where did the resistor wire come from go to

If it's an 89 I doubt it will have one. I think they were only used on engines with points but could be wrong. Think the wire was in the loom which run from the fuse box to the coil. I'm no expert and maybe someone will be along to confirm this. It does sound like your coil is not getting enough voltage though has the starter is zapping it. Have you got the right size battery for the engine?

You didn't say which injection system, but if its K-Jet mechanical then what can happen is the voltage drop during starting means the fuel pump doesn't deliver at high enough pressure, so no fuel is supplied during cranking.

It normally only prevents starting when warm, because the 5th injector should fire when cold - does yours?

It can be easily tested by squirting Easy Start, or petrol, or brake cleaner etc into the air intake just before trying to start - it will be enough for a few seconds, to start the car, then the fuel pressure will probably build up.

Check the obvious - that the pump isn't restricted (small filter blocked up on its inlet?) poor wiring, poor relay, and the 5th injector etc

https://clubgti.com/forums/index.php?threads/195423/

Did you get this sorted? Interested in what the problem was.