Skip the auto shop - Our mechanics make house calls

Q: Truck will crank, but engine won't start - 1973 Chevrolet K20

asked by on

The old battery in my car would not hold a charge, so I replaced it with a new one. After installing the new battery, the truck will crank, but the engine will not start. I held a plug wire next to ground to test for spark, but there was nothing. I also used the same technique to test the coil wire - nothing. Next, I tested for voltage across the input wires to the coil. When the ignition engaged, there were only 4 volts. Next, at the ignition fuse, in the fuse panel, I tested for voltage and saw 12 volts. I know that from the starter solenoid is the only other direction that the voltage comes from. When I tested there, it was 12 volts going into the solenoid, however only 4 were coming back to the coil. My truck’s starter is a new one that I installed several months ago. Next to the distributor is a small capacitor-looking part in the same bracket with the coil. I don't know if this is a resistor or a capacitor. There is only one connection that goes to the coil’s back side connection. I have been researching for wiring diagrams but so far haven't found any. Could you please give me whatever help you can for these problems?

A: Hello there, thanks for writing in. The wir...

Hello there, thanks for writing in. The wiring diagram for the ignition system of your vehicle is pretty simple. Power flows from the ignition switch to the coil. When the engine is cranked, the points open and close to create voltage in the coil secondary windings. This creates the high voltage needed to fire the spark plugs, which is sent to the distributor.

If there is no spark, suspect a faulty coil, coil wire, cap rotor, points or distributor. The wiring between the ignition switch and coil could also be bad. A faulty starter will not prevent the engine from getting spark.

It sounds like you've already spent a lot of time on this issue; if you'd like further assistance, consider having one of our certified automotive technicians come to your home or office to diagnose and repair your vehicle properly.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Where is the solenoid shift in a Toyota Camry?

If you are referring to a shift solenoid, that component is located within the transmission in a transmission "assembly" known as the "valve body." Failures of shift solenoids are not unusual, however, the Diagnostic Trouble Code that has identified this...

Q: How do I clean the engine in my truck?

The engine in your truck will perform better when it is free of grease and dirt. Grease and dirt build up over time and can be removed by a simple cleaning. To clean the engine. Cover up the electrical...

Q: Something is draining my battery, both battery and alternator have been checked and are working fine.

Hi. Your diagnosis is spot on! If the alternator and battery are good, something is causing a pretty significant drain on the battery, and this needs to be identified. This problem can be diagnosed by connecting an ammeter to the...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.