1985 Ignition troubleshooting (1 Viewer)

Joined
Apr 18, 2021
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Location
Durham, NC
Hi All,

I've worked my way through the FSM ignition diagnostics and have hit a bit of a dead end that I hope someone here can help with.

The background: was driving my 1985 FJ60 and engine shut off (260K miles, have had it about a year, drive it a few times a week, and, first time this has happened). Coasted to a stop, attempted to restart, no luck. Motor turns over, but won't catch. Waited a while, maybe an hour, tried again, and it started right up and drove home. Had one more short trip without issue, parked at home. Has not started again since then. Fuel seems fine, can see it in the site glass, hear the accelerator pump when the throttle is opened.

I have worked through the FSM ignition System 'On-Vehicle Inspection' steps:

1. Engine fuse is fine, both visibly, and, when resistance is tested with a multi-meter
2. No visible issues in wires and connectors
3. No spark from the coil when attempting start with coil wire disconnected from the distributor and close to ground
4. Source line voltage at coil is fine as per FSM
5. Power transistor off condition is fine as per FSM
6. Power transistor on condition, as tested in the FSM, is odd, and, something I could use some help on. When I apply the 1.5 volt battery across the distributor wire connector from the coil assembly, as per the FSM, I get a voltage drop across the coil and igniter body, but, it is only a drop of 1.5 from the engine battery voltage. FSM ways I should be a 5 V difference. I hear an audible clicking noise when I apply the 1.5v, but, is the lessor voltage drop significant?
7. Coil resistance readings are within specification in the FSM

Is the power transistor on condition test, with a 1.5 instead of 5 v drop indicative of a bad igniter? If not, does that point to a back signal coil (resistance reading across the distributor end of the coil to distributor connection reads ~200ohms across the poles) as the only remaining possibility? Any other ideas? I replaced the cap and rotor about a year ago, things looked fine in there at the time, and, have driven it a few thousand miles since then.
 

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