No spark from coil after replacing lots of parts

[BlueMaverick]

Hey guys new to this forum.

Picked up a 1985 ford ranger single cab long box, dual tanks.
Has a 2.8 carb, 2wd with a automatic trans.

Has only 123xxx Kms

Replaced the fuel filter and plugs to get it going, deal was if I got it started I could take it away, got it from my Grandfather in law.

Well drove it for a few days, put sea foam in it and 94 octane in the tank. It died that night for some reason.

Truck was getting fuel, poured gas down the carb.

No spark.

Tested for spark, had none.

Replaced the cap and rotor, the coil. Started up drove it for 30 minutes.
Parked it and it died.

Replaced the module on the dizzy.
Didn't help.

I then realized that the hull effect, or coil pickup was whooped, completely degrading.

Pulled the dizzy and replaced it.

Still nothing. Turns over but doesn't start.

Checked coil, no spark leaving the primary.
Used a test light to check the positive wire, nice and bright when the ignition was on.
The green wire barely even lit up.


What am I missing. Why am I not getting spark???

Help

-Haden

 

[Kevin Evans]

With TFI, there's several reasons that you might not be getting a spark.

There's a page in the tech library about diagnosing issues with ignition: http://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml

 

[RonD]

Welcome to TRS

What makes a Coil Spark?

It sparks because it LOSES POWER
The Primary coil gets 12volts full time when key is on, the + terminal
To get the Coil to spark the "-" terminal is used, the older "points" setup, and now the TFI module, will Ground and then Cut the Ground to get Coil to spark.
The Hall effect sensor in the Distributor(replaced the "points") gives TFI module the timing of when to Cut the Ground

So simple setup, power coil up then Cut that power and a spark comes out.

To work, the Primary coil has to have very low resistance, 2 OHMs or less, usually under 1 OHM, .5-.9ohms

So your dim test light on the "-" terminal could mean coil is bad.
Unplug the TFI modules connector, so it is no longer connected to the Coils "-" terminal and retest "-" terminal with key on.
Both + and "-" should show the same brightness with a Grounded Test light.

You can test the coils spark by simply giving it 12volts and a ground, then remove the Ground and coil's Secondary wire will Spark, showing you if it is weak, yellow spark, or strong, blue/white spark

 

[BlueMaverick]

Turns out...

I could not figure out why I had no spark.
Thought forsure it was the module.

Tried pulling the new one and put the old one back in.

Truck had great spark, fired right up.

Brought the module back because it was defective.

 

[AndyB.]

Nice work. Unfortunately it's becoming common to get parts that are bad right out of the box.

 

[RonD]

New used to mean "Tested and working"

New now means "Never tested but we warranty it"

Materials used to be expensive, and labor was cheap.
Opposite now, labor is expensive and materials cheap

Quality control, i.e. testing new parts, is labor

So to get parts to market at a cheaper price, what WE want, we are now the FREE labor Quality Control Department, lol.

So if a new part fails we take it back and they give us a new one, "here is the next part you can test for us"

 

[Doofy]

Great analogy, RonD. I've never thought of the 'why' of parts seeming to be of such piss-poor quality. Guess we brought it on ourselves by demanding "Cheap".

 

[BlueMaverick]

Ya seems to running pretty good, still stalling once and a while tho at a stand still.
Buddy of mine has a friend with a Dana 35 and a 8.8 out of a explorer, selling it with a 6 inch skyjacker lift. Cannot pass it up. Buddy also has a trans for me and radial arms he will give me. Looks like I'll be lifting the ranger pretty quick here after I clean everything up.

 

[BlueMaverick]

well, running... but acting up.

It chooses when it wants to run well and not so well.
It seems to hesitate and stall if I give too much throttle.
Don't know where to go from here...

Could it still be the Module I never replaced?

Spark or fuel.

how could I go about testing and ruling out which one is the issue?