Weak Spark and Truck will not Start?


New member
Oct 12, 2019
What suggestions do you guys have for this?

The problem started happening when I tried to change the key cylinder because of when it is cold out it is super hard to turn on.....

But now it will crank and crank but will not turn over, she almost got there a few times what should I check?

I am too the point of taking apart the steering column to investigate if any parts are broken. Is this the best first step? Please let me know your guys suggestions.


Active member
Staff member
Oct 18, 2005
Coronado, CA
Yo zkyllonen,
Try a Self Test for Diagnostic Trouble Codes by my pal, BroncoJoe19 @ https://www.broncozone.com/threads/code-reader.14269/
Of course, do just tge Key on, engine off portion.

Primary Voltage
1.Attach the negative lead of a voltmeter to the distributor base.
2.Turn the ignition switch ON and connect the positive voltmeter lead to the negative (-) ignition coil terminal. Note the voltage reading and turn the ignition OFF. If the voltmeter reading is less than 90 percent of the available battery voltage, inspect the wiring between the ignition module and the negative (-) coil terminal, then proceed to the Ignition Coil Supply Voltage test.

Supply Voltage
1.Attach the negative lead of a voltmeter to the distributor base.
2.Turn the ignition switch ON and connect the positive voltmeter lead to the positive (+) ignition coil terminal. Note the voltage reading then turn the ignition OFF. If the voltage reading is at least 90 percent of the battery voltage, yet the engine will still not run; first, check the ignition coil connector and terminals for corrosion, dirt, and/or damage; second, replace the ignition switch if the connectors and terminal are okay.
3.Connect any remaining wiring.
miesk5 Note; don't replace ignition switch unless it fails this Logic Test; Switch Pin-Out Diagram & Continuity Testing (Logic Tables in 87-91 (from Factory Manual and the Ford Electrical & Vacuum Troubleshooting Manual (EVTM)
Source: by Broncobill78 (Dave) at Ford Bronco Zone Forums
miesk5 Note, due to recent Bronco Zone "site upgrade", the Logic Test is gone. But here is a copy I have in my site;

Secondary Voltage
1.Disconnect the secondary (high voltage) coil wire from the distributor cap and install a spark tester between the coil wire and ground.
2.Crank the engine. A good, strong spark should be noted at the spark tester. If spark is noted, but the engine will not start, check the spark plugs, spark plug wiring, and fuel system. If there is no spark at the tester: Check the ignition coil secondary wire resistance; it should be no more than 5,000 ohms per foot. Inspect the ignition coil for damage and/or carbon tracking. With the distributor cap removed, verify that the distributor shaft turns with the engine; if it does not, repair the engine as required. If the fault was not found proceed to the Ignition Coil Primary Voltage test in below;

Troubleshoot a CRANKS, BUT NO START Ford 4.9, 5.0, 5.8) @ https://troubleshootmyvehicle.com/ford/4.9L-5.0L-5.8L/how-to-troubleshoot-a-no-start-1
" If no codes, I would say to try & replicate the no-start situation & have a spark tester & fuel pressure gauge ready to test." by mrnewland1


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