No Spark 1975 351w

[redfishtony]

Ok guys, I'm about ready to throw in the towel. Last week we got the 1969 sport running like a top. New starter, battery, solenoid, ECM,voltage reg,all was good. Then Sunday afternoon lost all spark. The motor is a 1975 351w out of an LTD. I have tried to trace all the wire but it's a mess. It seems when I used my test light with ignition switch on I have power to both side of the coil.this doesn't seem right. Why would it just suddenly stop firing. How about the pickup in the duraspark distributor? Is there a way to test it. They have two wires spliced into the wires at the switch. One is hooked to the green wire and the other is hooked to the red with blue or grey stripped. There got to be some sanity. Thanks for any advice or ideas.

 

[Bully Bob]

"...with ignition switch on I have power to both side of the coil.this doesn't seem right."

No, this doesn't seem right. Just a guess., maybe the coil shorted out..??

Electronic ignitions req. certain coils depending on the (ECM) mfgr. of the ignition. 

Also, two types. One type is "Halls affect" ---- (can't recall the others callout)

"How about the pickup in the duraspark distributor?"

These can fail but it's pretty rare. Good news, they're inexpensive.

Keep us posted...

B

 

[Rons beast]

Hey Red,

Connect a test light between the + and - terminals on the coil.  Crank the engine.  The light should flash.  

Got a flash= bad coil.

No flash = indicates a breakdown in the primary ignition.

If you have 12 V at the + terminal with the key on then the module is not giving a ground to the coil. (the providing of a ground, then removing it is what "fires" the coil.)

that should come from a green wire.  HOWEVER!  the module gets a ground from a black wire from the distributor. Check that this wire is providing a good ground.

Many off-roaders have spliced in a strong ground direct back to the battery to prevent problems from lack of ground.

Check these wires if intact, suspect your module.

Good Luck

 

[Bully Bob]

Hi Ron..!!

Not to 2nd guess but.., I'm struggling to understand;

"needs to flash but, if it does--- bad coil"..?

"no flash means ---- bad coil"..?

Also on my ignition, key off, no V to the plus side of coil.  Key on, there's a constant 12V

 

[redfishtony]

Well it appears to have been the ECM on the wheel well. After replacing just about everything they told me tonight the module was bad. Still not convinced myself but will know in the morning. I changed out the starter, ignition coil, regulator, a complete new distributor.I'm also going to unlock and clean the engine ground. After hours of reading why these modules go bad it appears either heat or a short is the most common reasons. The module they told me is bad is only 2 years old. This all started last week when the new battery drained overnight. The reason I replaced the regulator was because when I hooked up the battery charger it got hot as ****. The key was left in the on position was the reason. The man at the parts store said it probably burnt out the ECM. HOPEFULLY tomorrow well be back up and running.

 

[Bully Bob]

What's the latest..?

 

[redfishtony]

Top Gun, Been bust so I haven't been checking up on things. I replaced everything and it cranked up and ran like a top. After about 10 minutes we shut it off and guess what, nothing. I was mad as a wet hen but was convinced it was something strange going on. At that point I tried jumping it and while doing so the positive battery cable made a strange spark. After a closer look, where the red insulation went under the lead post cover or cable end, the copper wires inside were almost corroded completely away. Switched it out with a new one and all is good. It was something so simple all along but was not visible due to the plastic coating on the wire. New fuel tank, lines and filter going in tomorrow. Thanks for checking. TW

 

[Bully Bob]

KEWL...!!

Good job..!   Ya., sometimes the simplest issues are the hardest to find.

Keep us posted & some pics if ya have time...

B