Engine fires but doesn't remain running?

[Mr.SA]

So I was filling up today and when I went to start my Delica again it would crank and you could hear it fire for a second then die. Usually it starts instantly with no problem. It was just after 2-3 hours on the highway (temp gauge stayed around 1/2 or lower, only going up to 2/3 on hills)
Now, there's a random switch that the previous owner installed. I have no idea what it does. I flipped it on and left it on just to see if I'd notice anything (first time I've left it on)
I let it sit for another 5 mins, turned the switch back off and it struggled a little then fired up and idled fine. Now it's running normal.

It's never done this before so I'm assuming either that switch did something or it really was having trouble hot starting.

Anyone know what could be going on? I'm in the middle of a 20 hour road trip and want to make sure I don't end up stranded!

It's the 2.5 TD btw

[Growlerbearnz]

That's creepy. There shouldn't be anything electrical that can cause a diesel engine to run better when it's on, unless it's glow plugs and the engine is stone cold.

Back to basics. Check your oil and water for level and contamination. Injector pump for fuel leaks or split fuel hoses (air leaks). What you have sounds a bit like an air leak on the fuel intake side, so pay attention to that area.

Photos of the engine are always welcome...

[Mr.SA]

Well I've started it probably 6 times since then and it fires right up. I'm guessing it was that switch. Which is really strange because it runs fine with if on. But died instantly when trying to start it. Maybe it's some kind of anti theft deal, can't think of any other purpose. I'm scared to touch it now!

[Growlerbearnz]

Good thinking! It might interrupt power to the fuel cutoff solenoid on the back of the injection pump.

[FalcoColumbarius]

Could the switch be a part of a veggie install?

Falco.