Truck starts then dies in 3-5 seconds

Never had an issue with this until last year and I leave my keys in the truck ALL THE TIME. Had my truck since 2013. It's a 2008 TRD Offroad.

It's happened twice. Both times it's happened, same situation. Go to pull out of a parking spot truck dies in gear in 3-5 seconds after seemingly normal startup. Try to start again and truck starts but dies in 2-3 seconds. Each time I try to turn it over, engine run time gets progressively shorter until it won't crank over at all. Starter acts fine, no electrical issues. Almost acts like a fuel delivery issue.

This has only happened twice in 10.5 years and not until a year ago and like I said key is left in the ignition all the time. Both times there has been a significant temperature swing to colder temps. This is the only commonality I can find. This makes me think something is wearing out.

I have done the 3 key turn on/off cycles pulled the key out and done the 3 lock/unlock cycles and she starts right up. I will try just removing and flipping the key next time. Wondering if the sensor ring around the ignition is wearing out? Hope this helps confirm a couple of these posts for people and gives a solution.

Anyone know why this is happening?

 

You're sure there's gas in the tank?

It's not all that common but there can be issues with the fuel-sender unit that cause the dashboard fuel gauge to read false-high. If there's any question put a few gallons of fresh gas in to rule out that possible cause.

 

What codes do you have.
Also could be a plugged cat. Take out the upstream o2 sensor(s), put in some ear plugs and see if it still does it

 

It's possibly a security issue but 2nd gens typically won't start at all if the immobilizer is activated, when it does it see if the security light next to the clock is blinking with the key on.

One thing that comes to mind is the fuel pump relay that possibly has a failing contact, the truck starts with the fuel pump relay in high speed and it switches to low speed a few seconds after startup.
Note that it is a 5 pin relay so don't make the mistake of swapping it with a 4 pin relay.

 

Would the fuel pump resistor play into this?

 

Lots of things it could be. When’s the last time the fuel filter was changed? Put a gauge on the rail or try hitting the Schrader valve when the ignition on, engine off. See if you have pressure

 

A problem in the resistor most likely wouldn't be intermittent.

2nd gens don't have a fuel filter or fuel pressure test port nor do they do a key on prime, the only way to test fuel pressure is to tee into the line at one of the quick connect fittings with the appropriate adapter and gauge.

 

Banana in the tailpipe

 

I think it’s worth checking, tho. Water splashing up there, getting jostled around… it’s easy enough to get to and verify the connections look clean and the resistor is still a resistor, might as well rule it out.

I’m dubious too but, you know, easy stuff first…