1979 FJ40 no spark issues (I have read all the threads on this issue) What am I missing or failing to check

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Wadesters

Wadesters

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Newnan, GA
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www.cwcruisers.com
I have to be missing something simple. Body was off the frame for a restore. After body was re-installed I ran the engine and everything was fine. I then installed vintage air which is completed but I do not have the vintage air wiring hooked up yet. I do not have the front fenders or front bib on yet.

Ground cable to battery is getting a good clean connection on frame.
Igniter and coil tested in another 1979 FJ40 and worked fine in that one.
Igniter is grounded directly to battery.
Double checked all connections and they seem to be clean and have power.
All fuses show good.

Distributor is a no points OEM.
New alternator installed but hooked up the old one just to make sure that was not the problem.

Only thing I notice irregular is when running a test light to coil positive side test light is very dim. No illuminated light on negative side of coil. This was the same on the other FJ40 I tested the coil and ignitor on. However when the test vehicle started both positive and negative sides of the coil illuminated bright.

I feel it must be a ground but don't see anything missing.

Any ideas greatly appreciated.
 
Check the voltage at the fuseblock, check the voltage at the ignition switch. IIRC, it’s Black w/yellow stripe.
 
What’s happening when you try to start the truck? Any sound at all? Does starter turn the engine?

Thoughts...

Fusible link bad... or fusible link connections are loose.

Battery- to frame ground may not be as good as you think... is the ground strap good?

Starter case to frame ground good?

Do you have a engine-to-frame ground? Might help.
 
I hot wired the + side of the coil and ignitor directly to positive battery terminal and no go. I do have another year specific (79) distributor out of a parts vehicle. Can I change just the pickup coil or must entire distributor be changed?

I have not checked voltage at the fuseblock, check the voltage at the ignition switch yet. I don't have my multi meter here at the moment.

Thanks!!
 
I just went thru this with an aftermarket electronic dizzy. I couldn't figure out where the disconnect was. I had power to the dizzy but not to the plugs. Thus I removed the aftermarket electronic dizzy, reconnected all the igniter wires and installed one of the new 61180 points dizzy. Fired right up...go figure.
 
Wadesters said:
The only ground it has is the negative terminal wire bolted to the frame.
Click to expand...

Mine’s a ‘78... I don’t know ‘79.

But, I believe you still need a ground strap, from the starter case to the passenger frame rail... to a bolt on the back-PS corner of the splash guard.

With no good starter ground, the starter turns, but the motor doesn’t start.
 
as mentioned does your engine have a ground strap? Maybe temporarily use a jumper cable to ground engine to frame.
FJ40Jim said:
.......There should be a ground cable from batt. to frame or batt stand right in frt of batt. There should be a ground cable from RH frame rail to starter bolt or engine mount bolt.
Click to expand...



Here’s a handy testing writeup
FJ40Jim said:
A cross post from a email to a customer:

You can test the complete 81-87 2F ignition system on the workbench.

Supplies:
  • A coil & ignitor assembly and a distributor assembly
  • a source of 12VDC power. I use a gel cell battery from an old computer battery backup. A car battery or a 12V rechargable drill battery are also good sources.
  • test lead wires w/ alligator clips
  • clean sparkplug gapped at ~.040"
  • known good coil or plug wire
  • large vise grip or small c-clamp
Setup:
-remove cap & rotor from dissy.
-insert coil or plug wire into end of coil.
-insert sparkplug into end of coil wire.
-Clamp plug body to foot of coil w/ vise grip or small c-clamp, so that plug gap is visible.

Connections:
-plug ignitor lead into dissy.
-connect -12V lead to mounting foot of coil
-clear the area! connect 12V+ to coil + terminal. ignition is live now.

-spin dissy shaft by hand. spark should be visible & audible at plug.
-disconnect battery. watch out, coil will spark one last time when battery is disconnected.

HTH!

PS: can a mod stick this on the tech page?
Click to expand...




And professor Jim’s response on how to test pre-81 stuff
1902054
 
Last edited:
You seem to be missing the point...

At a minimum you need:

Battery-negative to PS framerail ground strap...
you already have this

Starter-body to PS framerail ground strap...
DO YOU HAVE THIS?


A third ground strap may help

Engine to frame... do you have this?
 
What I have determined is that there are two connectors coming into the igniter. One is a two wire connector with both wires black and yellow coming from wiring harness to igniter. When this plug is connected I have 12volts on both sides of the igniter and also to the distributor.

The other connector is a single yellow wire coming from wiring harness. If I plug this wire in I lose the 12volt connection in the other plug. Power to the coil is dim on one side and the other side none at all. This plug seems to run feedback and cancels everything out when connected. However even when this wire is left disconnected not getting spark to fire engine. I traced it to what I believe is its origin and seems to go into the emission control box. (This vehicle emissions have been removed).

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The single wire coming off the ignitor is Tach output to emissions computer. It does not need connected for engine to start.

The 2 wire plug is 12V to ignitor and ballast Voltage to coil. Both those need power to make spark.

The ignitor needs a good ground to make a spark. It grounds through the mounting bracket.

The pickup coil in dissy is an EWOD (either works or don't) part. Check it with an ohmmeter, should have no continuity from either terminal to ground (dissy body) and 150-ish ohms across the 2 terminals. They usually break a wire and have infinity ohms if they are dead.
 
Today I took @FJ40Jim advice and checked the ohms at the distributor. 150 just like it should be. I attached a battery ground cable to the ignitor mounting bracket and the other end to the negative battery cable. Both sides of the ignitor light up under a test light with 12 volts. I have a spark tester and still no spark.
I am starting to think although it is something simple it is beyond me. I am missing something but have spent many days on it. I have run out of ideas and tested everything I know to test.
 
Do you have any other 78-87 electronic ignition parts on the shelf?
If yes, try plugging in another dissy to the ignitor and spin it by hand, should get sparks out of coil.
Plug the current dissy into another coil&ignitor unit. Supply with +12V from battery and clamp to engine for ground. Crank engine, should get spark out of coil.
 
@FJ40Jim Before I saw your post today I tried a test on the internet I found to test the coil (even though I tried it in another vehicle before). It had me hook the coil up straight to the battery, with a wire into the coil and the other end hooked to a spark plug laying on the negative battery terminal. Then hooking a test wire to the negative side of the coil and brushing the other end on metal and seeing if I received a spark out of the spark plug, I did.
Next I changed the dissy pickup coil with another distributor I had from the same year. Also changed with new distributor cap and rotor.
Still no spark and will not run.
 
Sounds like it may be a bad ignitor. The 78-80 ignitors do not have as much self-protect built in, compared to the 81-later ignitors. If the early ignitors are left w/ KOEO or just cranked excessively, they can be burned up.

Do this test to verify:
<< Plug the current dissy into another coil&ignitor unit. Supply ignitor with +12V from battery and clamp to engine for ground. Crank engine, should get spark out of coil. >>
 
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