Problems on 1997 Ford F150

Symptoms for Problems on 1997 Ford F150
1997 Ford F150 engine
Problems on 1997 Ford F150 happened after engine installation. The engine on this started to knock last week after the owner forgot to check the oil. It had too many miles anyways. He bought a used engine from the salvage yard and according to the vendor, the engine was running when the engine was removed from a wrecked truck. It was totaled after a collision but left the engine intact.

The vendor checked all the engine compression readings and the oil pressure before selling it to him. The buyer installed it with a friend over the weekend and they did tune ups, filters and put all new fluids. They wanted to make sure everything will work once the engine is installed.

Problem is, after the installation, it won’t start. He connected a scanner and  there was no code. This showed him all electrical were working. He was contemplating whether to remove the engine and return it to the salvage yard. However, somebody recommended ATS to him and this is how I got the symptoms of his problems on this 1997 Ford F150.

Diagnosis for these Problems on 1997 Ford F150:

Not all scanners “no codes” are not electrical problem. When analyzing this no starts… begin with the basics by testing for sparks and fuel since we know the engine was tested good.

Testing for sparks:

1.) using a $5 spark tester, check if you see steady blue spark at the plugs. Test at least 3 spark plugs. In none, go next to step 2.

2.) check for 12v at red/light green wire at the ignition coil wirings when you turn the key on, engine off. This same red/light green wire is your power supply coming from the vehicle fuse/relay. Together this same wire is hooked up with 3 other wires which are the ground signals from the ecm. If you can use a test light to test those 3 wires, you can check if the ecm is working. During cranking, each of the 3 wires should blink. If not, ecm is not good. However, if they are blinking and you have no spark at the plugs, ignition coil bad. If the 3 wires are tested between the ecm and coil for continuity and are OK, problem is definitely the ecm. Furthermore, the ecm can be tested by verifying the power and ground supplies at the ecm terminals. The power supply is 12v and ground supply is 0.250v max respectively with key on engine off. If during this ecm test, if you also find the 5v reference at pin 90 terminal is less than 5v, then I am almost 100% certain that the ecm is defective.

Testing for fuel:

1.) With key on, engine off, test the red wires going to the injector wiring harness. You should get 12v or check the fuse.

2.) Using a $10 noid light tester available from your local parts store, test the noid light tester for blinks when the injector plugin is connected. Do this during cranking. To prevent the engine from starting, you may disconnect the power supply wire to the ignition coil.

If no blinking shows up on at least 3 injectors, trace the injector wiring harness from the injector up to the ecm. You might need an ATS wiring diagram to do this. The resistance of each wire must not exceed 5 ohms or you have a short or open somewhere. If wires are OK, then it is a safe assumption that the ecm is not sending ground signal to the injectors.

3.) A quick way to check fuel is to spray carb cleaner fluid at the air intake opening. If engine starts then problem is either injectors or fuel pump. If you put your ear in the fuel tank filler tube, you should hear a humming sound when you turn the key on. That indicates that the fuel pump is working. Make sure you check the fuel pressure by cracking loose the fuel line connection near the injector fuel rail. Be careful of spilling gas on a hot engine though.

Final Fix for these Problems on 1997 Ford F150

When the vehicle owner got this message, he traced the broken wiring for the injector wiring harness (red wires 12v supply) was cut when they were installing the engine.

More Tips on these Problems on 1997 Ford F150:

1.) Get hold of ATS wiring diagrams whenever undertaking engine installation job.

2.) Whenever buying used engine, always do the compression test yourself. This will avoid any doubts in your mind later after the installation.

3.) Terms such as noid lights and spark tester are discussed more if you visit ATS.

Thanks,

Richard

1 Comment »

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