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Thursday, May 19, 2011

Car/jeep no start troubleshooting?

When you turn the key to START it what happens?
1) Nothing happens? (dead battery?, loose battery cables, or it's not in "park" all the way.)
2) You hear a "click", but nothing else? (loose battery cables, bad starter, bad starter solenoid, or broken engine)
3) You hear the starter turning, but the engine doesn't turn? (low battery voltage, bad starter or bad ring gear on flywheel/flex plate)
4) The starter turns the engine, but the engine won't start up? (out of gas, bad fuel pump, plugged fuel filter, broken timing belt, no spark)
5) The engine turns over, but very slowly. (weak battery, worn starter, out of engine oil)
6) the engine turns, but there's an awful banging noise? (something is broken inside the engine)


Engine cranks normally, but it does not fire:
You turn the key to start and hear the starter motor crank the engine, but when you release the key, the cranking stops and there is silence. This means that the battery and starting motor are working properly, but the engine is not firing. If you continue cranking the engine over in this way, the battery will eventually run down and will need to be recharged, but the battery and starter are not the cause of your problem.
There are a number of causes for this type of no-start condition, the most common being that you are simply out of gas. Assuming that you have fuel in the tank, you will need to go through a series of tests to determine what is causing the problem. The testing procedure is as follows:---

Spark:---------An easy way to test for spark is with an inexpensive spark tester. This is a device that is readily available at most auto supply stores. You use it by simply holding it next to a spark plug wire. If you see the neon lamp flashing while someone cranks the engine, then you have spark and should move on to checking for fuel. If there is no spark, or a very weak spark, you will have to replace the spark plug or the coil pack.It has to be checked.

Fuel:
First step here is to listen for the fuel pump running inside the gas tank. When you turn the key to run, you should easily hear the pump come on, run for a few seconds to build fuel pressure, then turn off. If you do not hear it, it could mean that the fuel pump or circuitry is bad. (Fuel pump failure is a common problem).

Fuel injected cars are very sensitive to proper fuel pressure. If the pressure is off, even by a few pounds, it will cause noticeable performance problems, or a no-start condition. To check for proper fuel pressure, you will need a fuel pressure gauge that is suitable for your type of system. Or you can also get the fuel pressure tested at local car garage, If fuel pressure is low then its a fuel pump and fuel filter related problem.

Compression:

If you know that you have spark and fuel, the next step is to check for compression. For this, you will need a mechanic's grade compression tester that will screw into a spark plug hole. You will need to remove the spark plugs and use the compression tester to test the compression on each cylinder. If the compression is very low on all cylinders, that is a sure sign that the timing belt (or timing chain depending on the engine) has failed and will have to be replaced.

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  • Make sure that you have enough gas in your car. This sounds like common sense but many people don't think to check this before wondering why their car won't start. Try to refill your tank when it is no less than one quarter full, or you risk getting stalled or stuck somewhere.Verify that the battery has a full charge. A battery with a low or partial charge can cause the engine to crank too slow preventing it from starting. Sometimes a jump will fix this problem, but if your battery is more than five years old you should consider replacing it, especially if winter is only a few months away.Check to see if your fuel pump is turning on. This can easily be done by putting your key in the ignition, turning it to the "on" position, and listening carefully with your ear pointed toward the back seat. If your fuel pump is working you will here an electric "whirring" noise for about 2 seconds every time you cycle the key on and off. If you hear nothing then your fuel pump is faulty or not getting any power.Find out if the engine is getting gas to it. Sometimes a plugged fuel filter or a problem with the fuel injectors can prevent the engine from getting any gasoline. To check this remove the air cleaner and smell inside the throttle body or air cleaner housing. If the engine is getting enough gas you should be able to sense a strong gasoline smell due to the amount of uncombusted fuel left inside the intake manifold.Determine whether the spark plugs are firing. If there is plenty of gas but no spark, the engine will crank but not start. Unplug one of the spark plug wires and plug in a spark tester.

  • This troubleshooting will let you know the problem.Thanks.


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