[afrustrated1]

I have a 99 ford Taurus drove it to take little brother to lunch brought it home and it hasn't started since new battery turns over good tries to start just won't run

[TxGreaseMonkey]

Basic Ignition System Troubleshooting

Greater than 90% of all "crank but won't start situations" are electrical-related,not fuel. The tests below assume there is no problem with the timing belt orengine compression.


A summary of tests that should be followed, if you are experiencing a"crank but won't start situation," are:

1. Battery Test. Remove and fully charge the battery. Most auto parts storeswill test and charge batteries for free. Clean the battery terminals andconnections.

2. Fuse Test. Check all under hood and under dash fuses with a test light ormulti-meter.

Using a test light or multi-meter is faster, more accurate, and eliminates thepossibility of replacing a fuse in the wrong slot. This is easy to do in thedark and cramped location of most under dash fuse boxes. Be very thorough,since it will save a lot of time and money. Determine everything that is on thecircuit, for a fuse that blows.

3. Check Engine Light (CEL) Test. Turning the ignition switch to ON, does theCEL come on and then go off after 2 seconds? If not, a fuse may be bad; the PCMmay be failing; the main PCM ground may need cleaning; or the ignition switchmay be bad, due to wear, pitting, or melting.

4. Fuel Test. During the 2 second interval that the CEL is on, do you hear thefuel pump in the gas tank run? If not check the fuel pump fuse and fuel pumprelay, in the under hood fuse/relay box. Remove and clean the contacts to thefuse and fuel pump relay. Consult your Owner's Manual for their locations. Ifyou hear the fuel pump in the gas tank run, the odds are that the fuel pump isfine. Modern-day fuel pumps are extremely reliable and rarely ever needreplacing. Many mechanics, who don't know what they are doing, rush to replacefuel pumps. $750 later, the customer finds out the fuel pump was fine and wasnot the problem after all. Instead, focus on understanding the electricalaspect of the fuel system, including the ECM. I've seen many cases where simplycleaning the main ECM ground solves the fuel problem.

5. Diagnostic Trouble Code (DTC) Test. Attach a code reader to the under dashdata link connector, turn ignition switch to ON, and record any codes that werethrown.

6. Spark Test. Perform the standard spark test; i.e., remove a spark plug wireand attach it to a properly gapped spark plug, touch the plug to a convenientground, and observe the spark, while someone cranks the engine. Look for agood, solid spark. If the plugs don't spark properly, a) replace the IgnitionControl Module (ICM) and coil, or b) replace the Crankshaft Position Sensor(CKP) and coil on distributorless ignition systems (DIS). ICMs, especially, arevery problematic. I recommend replacing ICMs, CKPs, and coils every 120,000miles or 10 years, whichever comes first. Bench testing ICMs and coils are notreliable. Frequently, even if the plugs spark, the ICM is bad because heat hasaffected the microchip inside and it does not fire when the PCM wants it to.Crankshaft Position Sensors set ignition timing, supply the RPM signal, anddetermine engine speed.

SUMMARY

If the CEL comes on and goes off normally, all fuses are good, there are nocodes, you have spark, the fuel pump runs, but the engine does not start, theICM or Crankshaft Position Sensor (CKP) may be bad and should be replaced.CKPs, because of their proximity to the crankshaft and exposure to the elements(water, salt, grease, dirt, and stones), commonly fail. Before replacing theCKP, try removing and cleaning it with WD-40 and a rag. Exposed to high heatand vibration, the extremely thin coating of insulation on tightly wound CKPcoil wire can break, causing an internal electrical short. Heat can, also, crackthe sensor's housing and even cause the coil windings to expand, leading tofailure.