[TriumphStag]

Sorry all for the radio silence. Been a lot going on in life lately but happy to report all under control now, so time to get back onto this problem-mobile :-)

To make it a bit easier to explain, the car with the problem is my Red 75 - I ended up buying another 75 (Silver) back in January so have been running round in that for the last few months. Now I have some time to be rummaging around in engine bays, I have done a bit more testing.

I took the injectors out of the Silver 75 (which was running absolutely fine), and put them in the Red one, the problem remains, although it does start much quicker when it has just been running. I put the injectors out of the Red one in the Silver one - which was slightly rough at first but now continues to run just fine (I assume it took the ECU a short time to adjust).

So - that leads me to the conclusion it is not the injectors :-)


To summarise the problem again - it takes probably 5-10 seconds of cranking to get the engine to fire up. Once fired up, there is a nice big cloud of smoke for a couple of seconds (I assume the unburned fuel from all that cranking) and then it would run a little rough and cut out occasionally without warning - both when idling and also when driving.

Turning the engine off, and attempting to re-start immediately would also take 5-10 seconds of cranking.

I changed the injectors for a second hand set. The car still takes 5-10 seconds of cranking but "tries" harder. Best way I can describe it is:
Before: crank crank crank crank crank crank fire vroom
Now: Crank splutter faster crank splutter crank crank crank fire vroom

Turning the engine off after this and attempting to restart immediately would also take 5-10 seconds of cranking (including the splutter-cough attempts to start)

Swapping out the injectors with the Silver 75 results in the same behaviour - BUT when attempting to start immediately after turning the engine off it now starts after a second or two.

The Silver 75 always started fine after a second or two, and still does with the injectors out of the Red one.

The conclusions I draw from that are that the Injectors that were in the Red one originally were knackered, and that the second hand ones that I bought were much better. The ones from the Silver 75 were better again, but not much in it.

Per the thread, Cam and Crank sensors have been replaced, seals on the fuel pump regulator have been replaced and fuel filter housing replaced. Injectors have new rubber seals and copper washers, all inlet manifold gaskets have been replaced (plus EGR and inlet manifold cleaned out while it was off). There are no visible fuel leaks anywhere.
The fuel tank is over half full and the ITP hums away as expected when the ignition is on as does the HP pump down by the alternator....


It almost feels to me like the fuel is draining back to the tank and taking time to build up pressure again. I noticed a post about the check valve above. I will have a look at that tomorrow evening. In the meantime - any other ideas anyone?