M100 Not Starting (another one!)

[riksit2000]

Did you fix your not starting problem ?.

Morning Alan, no, I'm about done in now!
I'm now looking at fuel regulator write ups, keen to understand how this would/could impact starting.
Last weekend I had the fuel pump out, tested OK, giving 50lb of pressure when running to a blank end (i.e. not in the fuel flow, haven't got he equipment to do that yet). A very strange thing happened after the install, the car ran on for 20 seconds or so with the inertia switch triggered, i.e. pump not running, I had primed the fuel line before triggering the inertia switch. Really bizarre.
New coils fitted, just to cover that off. HT leads due today, however, pretty certain they won't fix it.
Stripped timing set up for the 3rd time yesterday, all looks spot on (took photos this time to remind myself I'm not going mad).
Keep going back to the question of why it runs longer with the inertia switch triggered than under normal conditions, hence reading up on fuel regulator. My logic is questioning if the pressure could be too high to allow the injectors to physically operate? Is that possible?
Nothing shows on the Elanscan, well nothing that rings a bell with me.
Should I assume that the ECM is OK as I can see it with Elanscan? If there is anybody in the north east that has a unit I could borrow to test, it would be much appreciated!
Any suggestions would be gratefully received.
Today I'm going to work through the inputs and outputs of the ECM as per the write up in EMK4 in the engine management manual.
If anybody wants to see a video of the issue: https://youtu.be/ImIDXwgsj5s

Cheers all, support is very much appreciated.

[Simon_P]

Hi, did you check the things mentioned previously? What did you find?

[riksit2000]

Hi, did you check the things mentioned previously? What did you find?

Hi Simon, yes everything checked, nothing found as yet.
Bit of a discovery in the last few minutes, I'm not getting fuel back through the return leg all of the time. I've just removed the bottom filter to ensure that isn't blocked, this has resulted in the car running longer when the inertia switch is tripped. My current thinking is that when under pressure, the pump doesn't seem to be able to do it's job, however, after an emptying of the fuel line (when ran with inertia switch tripped) the pump can charge the system to point where I get fuel returned to the tank.
Does anybody have any thoughts on this theory?
I'll be looking for a fuel pump now, I think that's worth a punt. Any advice on where to get one?
Cheers
Richard

[riksit2000]

NEW NEWS!
The pump is over delivering, it looks like the regulator is not always returning fuel. I've managed to cobble together a make shift pressure line (Old foot pump gauge and some fuel pipe) and I'm seeing 80lb pressure from the pump with no return through the regulator. If I run the engine with the inertia switch tripped it runs until pressure is too low to keep going. I've managed to run the engine up to temp today by starting with the inertia switch tripped and resetting it as the engine is about to die, the regulator did return fuel in this instant (Its few and far between that I can make this happen!) So, I'm now looking for a fuel regulator!
I'll feed back if this fixes it.
Cheers
Richard

Video of how I tested flow: https://youtu.be/J3ERYGHUvrk, https://youtu.be/rqkWBSr1hM8

[riksit2000]

RESULT!
Happy to announce that the fuel regulator arrived this morning, and indeed did the job!
My conclusion is that the pressure was too high at the manifold to allow the injector ball bearing to be moved by the magnetic field created when the injector was energised, the initial start is a result of the injector cycle at ignition feeding a very small amount of fuel into the intake, after that, no more fuel. The engine ran on longer when the inertia switch was triggered due to the fuel pump not running and there being enough pressure and fuel to run 3 seconds or so.
That's my story and I'm sticking with it!