why every time i turn on my truck it turns off right away?

Answer 1

Hmm, I'll throw out some ideas not having a make and model and year:

1. Is the ignition lock still in the "On" position when you let go of it (the thing the key is in)?

2. If it's carbureted and not fuel injected does it do this in the Winter as well as the Summer season? What will happen in high Summer temp's is the choke will be open or not close all the way when you step on the gas pedal before you crank it. Also, the gasoline will have evaporated from the intake manifold channels and some if not all from the carburetor bowls. The carb and engine has to be re-primed by the fuel pump when this occurs and this only happens when the engine is cranking and the pump is pumping.

There are also other vacuum switches that control the idle when the engine is at temperature (and the brain box or engine management systems take over the engine timing and functions) and these may or may not be wide open or closed, depending on their specific function, when the engine is "cold" but the outside air temp's are very high and the vehicle is parked in the sun. The heat from direct sunlight will penetrate the hood and make these temperature sensitive parts and pieces react as if the engine is already warm or hot. It can reach 110-130F degrees under the hood when the car is parked in the sun even if the car has been sitting all day or all night and half the day.

The same can happen when you park the car and it's very hot outside and the engine is hot. The gasoline left in the intake manifold and carb will evaporate very quickly.

Many of the older ignition modules are very heat sensitve, too, and will act up when very hot.

My old truck starts with one quick crank in the Winter but can take several long cranks to start in the dead of Summer when the temp's are in the high 80's to100F degrees.

Now you know why every car manufacturer went to throttle body injection, first, and then multiport fuel injection.

The older the car the fewer and fewer temperature sensitive switches are on it and the high temp's create less trouble.

Good Luck!

Answer 2

More details would help. With this much info, I would say the Ignition switch starts the vehicle but doesn't stay on in ON position. Let me explain, when you turn the key to on position, the whole vehicle is energized. By turning the key to start the vehicle, you energize the starter, you start the engine then you let the key go. If in ON position there is no power to the engine, the car won't stay running. In this case you will need new ignition switch. However, if the car runs for a few seconds before it dies, then I will need a few more details.
Good luck!

Answer 3

trash in the fuel pump from running the truck too low on gas get a gas treatment and use it with 1/3 or less tank of gas or manually clean out the pump and filter!

Answer 4

Need more info like make model and year would help. Does it sputter or what, but just a stab in the dark, the fuel pump is not pumping. Could be a fuse or relay. It could also be going bad.

Answer 5

you may have a fuel delivery issue. it may be a good idea to have a local repair shop look at your truck as you may have some engine management problems.

Answer 6

My wife is like that. I have to tickle her ear. Check to see if u r getting fuel. Then spark. I am thinking clogged fuel line or faulty ignition switch