Truck turns on, runs for 2-4 seconds then shuts itself off

hey,

I have a 2009 tacoma. Very intermittently it will turn on run for 2-4 seconds then turn itself off. I have no idea why it's doing this. I have taken it to Toyota/private shops and spent over 1200$ in diagnoses and oil changes trying to figure out the problem. It happens 2-3 times a year and most recently shortly after washing it. After 10-15 minutes of waiting the truck turns on and runs perfectly fine. The shops have found Nothing ... any ideas ?

 

Spitballing, but kinda sounds like an ECU issue maybe? I know when I reconnect my battery after wiring up a light bar or something, it will do almost exactly what you describe. Start, run, run, die. About that fast. Restart it and it kicks on strong as ever.

EDIT: Sounds like your issue may be moisture related? You mentioned washing your truck. Did it die the other times after a rain storm or driving through wet streets?

 

ECU ? Electric control unit ? Thanks for your reply. My thoughts are also it is a short of some sort in electical. I have an after market starter and lights but this issue happend before those were installed. I'm hoping it's as simple as a loose ground that is affected more when wet

 

Engine control unit. The brain of your engine. Basically controls EVERYTHING about your engine. But yeah, sounds like we might be on the right track...

https://en.wikipedia.org/wiki/Engine_control_unit

 

I'm not a mechanic, but I did sleep at a Holiday Inn Express back in May...

Fuel, Oxygen, Spark. One or more of those is being constricted or failing for some rare occasional reason.

 

Almost sounds like the fuel pump is doing its prestart prime (turns on long enough to raise fuel pressure to injectors and then turns off until engine starts) and then not kicking in once engine has started. Since it is controlled by the ECU you would think it would leave a fault code if ECU related or could be an intermittent open in a connector some place. Since it may be water related I would start at the fuel pump connector and look for discolored or corroded terminals in the both connector halves. ECU connectors are under hood and therefore not subject to getting wet at a car wash.
Good luck.

 

I had a wire on my remote starter get lose and I had this issue. Turned out to be the tach wire behind the OBDII plug

 

Bad Chip key.... try the other key and see if it happens