Stumped on a spark issue

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Feb 28, 2004
Divide, Colorado
So I just got back from a 700-mile trip in my 1977 FJ40 with all stock stuff under the hood and am totally stumped on this.

About 150 miles from home, I noticed a slight "miss" when taking off in first gear. Over the course of the next couple of hours, the idle got very rough and eventually the 40 could barely move under its own power. The engine only sounded normal at higher RPMs. It felt like it was running/missing on three cylinders by the time I made it home and wouldn't hold idle.

As it stands now, the truck won't start. There is a tiny spark when I remove the wire from the coil to the distributor and hold it against the frame. None at all coming from the spark plugs.

Here's what I've checked so far:

Swapped out entire coil assembly with my 1976 FJ40 and saw no improvement
OEM spark plugs are gapped and clean
OEM plug wires and in good shape
Carb float is operational and fuel is mid-way through sight glass
Verified functional fuel cutoff solenoid
Replaced fuel filter
Cleaned grounds at starter, battery, and coil
Removed instrument cluster and inspected ignition wiring for any obvious damage
Verified all fuses are good
Engine won't fire consistently, even with starting fluid

Any ideas? I am not an electrical guy and am afraid that may be where this is headed.
You haven't mentioned timing.
Do you have a voltmeter and can you check the battery ? Is it points or electronic distributor ?
You haven't mentioned timing.

I set it about a month ago (12 degrees advanced, IIRC). Ran beautifully.
Do you have a voltmeter and can you check the battery ? Is it points or electronic distributor ?

It's points; all original stuff. I probably need to get a voltmeter. It's an Optima Yellow top that's about 4 years old.
Did your dist. Clamp come loose?
Check the timing, see if it's were you left it
Is it this igniter?
The one that has points?
Edit I see its points.
All I can think of is the points condensor or possibly a faulty coil to dizzy HT lead.
Or the points gap is nearly non existent.

Man, I even swapped out the coil to dizzy wire and had the same issue. Maybe it’s time I swap out the dizzy points/condenser.
Did your dist. Clamp come loose?
Check the timing, see if it's were you left it

I tried to twist it to see if there was play, but it was still solid. I’ll check timing.

Thank you guys.
Cleaned grounds at starter, battery, and coil
Water/mud crossings while on trip? Might check and clean the block to frame ground connections.
Check to see if your cap and or rotor is cracked or damaged.
So how do you set timing on an engine that won’t start? I assume that cylinder 1 needs to be at TDC, but how does the distributor need to be oriented at this point?
Yes, cyl #1 at TDC, dizzy rotor should be under sparkplug wire #1 in dizzy cap (if not rotate engine another 360*). Traditionally rotor points towards sparkplug #4 in head. with key on, and power, cap on, rotate dizzy body, listen for slight "click" sound as spark jumps gap from rotor to sparkplug wire. Should be close enough to start there.
Would replacing the points be advisable
Good idea. Condenser too. Failing condenser will result in a weak spark, or at least it can in normal points systems. Don't know about the weird hybrid points/igniter system on your 40. I'm not even sure if the 76-77's even have a condenser, if the points are only used as a trigger for the igniter.

Also might be a good idea to put your original coil/igniter assembly back.
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If the original assembly is back on, check all your wiring, [still power to the coil+] make sure the rotor is back in the dizzy [I have done this multiple times]. Check The little graphite rotor button is in place inside the dizzy cap. It should be something simple. Unless the igniter died.

Also make sure the oem points you swapped have clean surfaces.

Also also. Is there a condenser/capacitor screwed to the side of the dizzy? or inside the dizzy? If so, you can try swapping it from your other 40.
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