1985 Ignition troubleshooting (1 Viewer)

[NCFJ60]

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.

 

[timhugh]

Having almost the same issue on my 81.

Symptoms are the same. Ran just fine, occasional start issues. I was suspecting the coil but everything is in spec by FSM, except my voltage drop on the igniter test was about 4v.

I would be tempted to swap the coil and the igniter outright but I’m having a hell of a time finding a replacement igniter.

Anyway, curious if you figured anything out and I’ll update if I learn anything.

 

[morganism]

Try the coil ground.
The hold down cage loses contact with body, and secondary can't collapse to fire.

Clean under the bolts, put a new wire from the igniter case to the wheelwell or the block, and it should fire fine.

 

[timhugh]

Try the coil ground.
The hold down cage loses contact with body, and secondary can't collapse to fire.

Clean under the bolts, put a new wire from the igniter case to the wheelwell or the block, and it should fire fine.

Thanks! I tested the ground on the igniter body and it was definitely well grounded (even cleaned up the mating surfaces on the bracket and igniter body to make sure) and still had no luck. In lieu of hunting down an old igniter for $$$, I swapped for a GM ignition module for now, and that seems to be working so I'm concluding that the igniter was dead.

Still not 100% on that since I was able to detect a voltage drop from the igniter when simulating a signal with a battery, which really seems to indicate that it was working, but it fired right up as soon as I completed the swap.

 

[Spike Strip]

It's very rare for the igniter to fail, but does happen. Could have been a temp-related failure...

I've read that the GM modules are not reliable when adapted to the toyotas. Don't know why. People carry a spare who run them or use some thermal paste to attach to a LARGE aluminum heat sink and that seems to help.

Some people have had success adapting Igniters from similar year 4Runner, Camry, etc ... don't remember the exact models but there are threads on it. Most of the 80s Toyota igniters differ just through the connectors, but the LC ones may be built to a higher duty level.

Since all these Igniters are 35+ years old now, sure would be nice if there were a plug 'n play alternative replacement. They won't last forever.

 

[timhugh]

It's very rare for the igniter to fail, but does happen. Could have been a temp-related failure...

I've read that the GM modules are not reliable when adapted to the toyotas. Don't know why. People carry a spare who run them or use some thermal paste to attach to a LARGE aluminum heat sink and that seems to help.

Some people have had success adapting Igniters from similar year 4Runner, Camry, etc ... don't remember the exact models but there are threads on it. Most of the 80s Toyota igniters differ just through the connectors, but the LC ones may be built to a higher duty level.

Since all these Igniters are 35+ years old now, sure would be nice if there were a plug 'n play alternative replacement. They won't last forever.

Yeah the lifespan of a replacement was definitely my concern. It was hard to look at my 40 year old igniter, then at one that looks just as weathered for $200 on eBay and feel like that was going to be a long-term solution.

I've heard the same thing about GM modules overheating, but I figure they're around $20 new and available at most auto part stores, so it's at least easy to replace. I also copied this approach and mounted the new module on the (now empty) case for the old igniter as a makeshift heatsink

Igniter Repair for Cheapskates

A couple weeks ago, my igniter died. One moment, the truck is idling in my driveway, and the next moment...eh...not so much. :censor: Not willing to spend a few hundred bucks on NOS (if I can find it), and not thrilled with the idea of spending $100+ on a used igniter, I hunted around the...

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This entire experience definitely has me considering reverse-engineering the old igniter and coming up with a drop-in replacement, though.

FWIW once I got it mounted on the "heatsink", I went for a drive and it is running much smoother than it has in the previous year that I've owned it, so it seems likely that igniter was slowly failing for a while now.

 

[Spike Strip]

I found a couple NOS American-made GM modules some years ago that I'm keeping for just this scenario. They still pop up on ebay once and a while. I think the Chi-Com made ones are the problem with reliability. It's like the old USA made GM HEI distributors where very very good ... Now, not so much.

I have no doubt if someone came up with a replacement igniter, particularly one that would work with the Sniper Fuel Injection, there'd be a truck-load sold.