My 03 5.3 flex engine burb will not start.

History was injector on 1st cyclinder underperforming fault - so bought replacement. Cleared fault after putting cleaner through the fuel system, no repeat of fault code so new injector not fitted.

A few weeks ago I noticed on one occassion an extended crank - to the point I got worried then it fired and ran pefectly.

Went on holiday for 2 weeks and now it wont start.

The engine cranks and appears to try to fire but never achieves a run. Nothing unusual on the dash.

I connected a scanner (Genisys) and it reported no current DTCs, in the history there was a P1626 - relates to the PASSLOCK not agreeing the key is correct and the ignition switch possibly had been tampered with.

However there are no current DTCs.

I have ensured all cables/connectors are well seated.

I have read of an earth problem relating to the engine and a connector on the firewall - so far no luck finding the connector - any help appreciated on that one.

I have read of a bad earth on the body control module - I know where the BCM is bit not where the relevant earth is...

The fuel tank is low, but the low fuel light has not come on. To check the fuel I pressed the schrader valve on the fuel rail when the ignition was on, there was a flow of fuel - but not a spurt - is that correct? Would a fuel pump problem or a dirty filter not set a fault code?

Spark plugs and leads are new ( few months ago) as is the battery which is cranking the engine over well.

Any help on ideas on where to go with this one would be really appreciated.

 

Sounds like fuel issue to me. You really need to check the fuel pressure.