Engine Cranks Then Doesn't - Ignition?

[LuvNLife]

OK; my new to me '85 C10 is sitting in the garage inop. Here's the story:

Just bought the truck this week. Had it towed home (torrential rain) and parked it in the garage. Was out with it Thursday and let it run for about 15 minutes and burn off any moisture left. It has no choke, so had to pump it, crank 3 seconds, repeat several times and it fired, no problem. Went out today to take it for it's maiden voyage, pumped and cranked twice for 3 seconds, on the 3rd try, dead. The lights on the add-on gauge cluster light, even the key buzzer works, but as soon as you turn it to start, they go out.

New last month battery with 850cca, terminals are tight, no hot wires, no smoke. Now, the key had felt like it was in a slight bind when you would turn it to start; now, there's no bind at all. This is wilh a non-tilt column.

Thoughts on where I could start troubleshooting? If it got into impossible to find steering column parts, and thoughts on putting in an old-school push button starter button as found on old trucks?

Thanks!

 

[K201979]

If its an automatic, try jiggling the shift handle and checking the wires on the neutral saftey switch. I cant tell u exactly where the switch is because mine hangs under the dash, but the wires should be purple. Mine comes disconected and theows me for a loop every once and a while. U will have power everywhere, but it wont crank. Good luck!

 

[F-64]

Check for voltage drops.

 

[chengny]

OK; my new to me '85 C10 is sitting in the garage inop. Here's the story:

Just bought the truck this week. Had it towed home (torrential rain) and parked it in the garage. Was out with it Thursday and let it run for about 15 minutes and burn off any moisture left. It has no choke, so had to pump it, crank 3 seconds, repeat several times and it fired, no problem. Went out today to take it for it's maiden voyage, pumped and cranked twice for 3 seconds, on the 3rd try, dead. The lights on the add-on gauge cluster light, even the key buzzer works, but as soon as you turn it to start, they go out.

New last month battery with 850cca, terminals are tight, no hot wires, no smoke. Now, the key had felt like it was in a slight bind when you would turn it to start; now, there's no bind at all. This is wilh a non-tilt column.

Thoughts on where I could start troubleshooting? If it got into impossible to find steering column parts, and thoughts on putting in an old-school push button starter button as found on old trucks?

Thanks!

This assumes a fully charged battery, an engine that is not seized, and that both battery cables are good (i.e. no shorts to ground, copper conductors are in good condition and properly connected to the fittings at both ends).

If moving the ignition switch to the START position can cause such a severe system voltage drop in an otherwise normal electrical system - to the point that even instrumentation lighting receives no power - that would point to an internal solenoid/starter issue.

When the ignition switch is moved from OFF/RUN to the START position, the only thing that changes is that battery voltage is supplied to the solenoid "S" terminal - from the ignition switch's SOL terminal.

With the application of 12 volts to the solenoid coil, the plunger is pulled in. When the plunger shifts, it drives (through linkage) the pinion gear in to engage the flywheel/flexplate ring gear. At the same time it closes a large set of contacts that cause full battery voltage to be supplied to the starter drive motor windings.

Point is; the only electrical components affected by turning the key to START are the solenoid coil and the starter motor. The lead that runs from the ignition switch to the solenoid coil is also energized while the key is in START, but because of it's relatively small diameter, even if shorted directly to ground it shouldn't cause the voltage dip you describe.

Might want to get your starter tested.

 

[LuvNLife]

This assumes a fully charged battery, an engine that is not seized, and that both battery cables are good (i.e. no shorts to ground, copper conductors are in good condition and properly connected to the fittings at both ends).

If moving the ignition switch to the START position can cause such a severe system voltage drop in an otherwise normal electrical system - to the point that even instrumentation lighting receives no power - that would point to an internal solenoid/starter issue.

When the ignition switch is moved from OFF/RUN to the START position, the only thing that changes is that battery voltage is supplied to the solenoid "S" terminal - from the ignition switch's SOL terminal.

With the application of 12 volts to the solenoid coil, the plunger is pulled in. When the plunger shifts, it drives (through linkage) the pinion gear in to engage the flywheel/flexplate ring gear. At the same time it closes a large set of contacts that cause full battery voltage to be supplied to the starter drive motor windings.

Point is; the only electrical components affected by turning the key to START are the solenoid coil and the starter motor. The lead that runs from the ignition switch to the solenoid coil is also energized while the key is in START, but because of it's relatively small diameter, even if shorted directly to ground it shouldn't cause the voltage dip you describe.

Might want to get your starter tested.

Thank you very much for the info. As luck would have it, I have a brand new "Tahoe" starter - HTPM - in the garage, just in case. All of your assumptions about the battery condition, cables, good grounds, etc. are accurate. I'll go over everything in the daylight tomorrow, though.

 

[75gmck25]

Another possibility is a bad ignition "rack" that is not moving the ignition switch electrical contacts into the proper position.

On the end of the ignition switch there are splines and they engage in a toothed rack that moves back and forth when you turn the switch. Connected to that rack is a long metal rod that runs down the column to the ignition electrical contacts (they are right above your feet on the column). If the rack is cracked/broken or the electrical switch is out of alignment, the switch positions may not line up correctly all the time. This is the part that may be broken.https://www.amazon.com/Ignition-Actuator-Replacement-Various-Steering/dp/B007TY1MZM Its a cheap part, but a PIA to replace because you have to break down the steering column quite a bit get access.

Bruce