1977 620 no start

[Dusten]

1977 620 L20B

Hei module

Non ballast coil

Ei distributor

 

Truck had been running flawless.

 

Last night on the way to work it was hard to start.  I assumed id flooded it, as after some extended cranking it started.

 

Ran fine on the way to work.

 

I went to go to lunch and no start again.  Nothing.  

 

Pulled the coil wire off the dizzy and didn't see spark while cranking 

 

12v at coil.

Coil measured 1.2ohm and 10.8k ohms.

 

Figured maybe a bad coil.

 

Grabbed a ride home and grabbed a spare hei module and a new coil.  

 

Still no start.  Still can't see to see a spark from the coil.

 

I'm a little lost.  

[banzai510(hainz)]

4 minutes ago, Dusten said:

Pulled the coil wire off the dizzy and didn't see spark while cranking 

Ypou placed it nearground and still no spark?

 

12volts to coil? Yes 12volts  then I assume dist. I always have a spare dist . Most coils dont go bad  unless a point dist one was installed and no ballast will COOK them(point coil)

I alwasy have a spare dist for cases like this but I never ran a Matchbox dist. Thy getting rare and very old,

 

Make sure you have 12volts and maybe clean the dist where it mounts to incase a weak round but Im just guess now.

 

if not 12volts maybe ck the fuse but assume you wont get a ignition light.

[Dusten]

2 minutes ago, banzai510(hainz) said:

Ypou placed it nearground and still no spark?

 

12volts to coil? Yes 12volts  then I assume dist. I always have a spare dist . Most coils dont go bad  unless a point dist one was installed and no ballast will COOK them(point coil)

I alwasy have a spare dist for cases like this but I never ran a Matchbox dist. Thy getting rare and very old,

 

Make sure you have 12volts and maybe clean the dist where it mounts to incase a weak round but Im just guess now.

 

if not 12volts maybe ck the fuse but assume you wont get a ignition light.

 

12v at the coil.  

I laid the coil wire on the manifold and couldn't see spark.  This is what lead me to coil or maybe the hei.  

 

The coil is the correct coil.  I replaced it when I went to the hei setup.  So I know it didn't get fried. 

It's not a matchbox dizzy

It's the earlier style ei.  

It could have failed.  It was in the truck when I bought it.  And I have no idea it's history.  

[datzenmike]

With ignition on a test lamp should light dimly if touched to the negative side of the coil. Shows power is present and coil primary is good.

 

With ignition on touch a grounded wire to the negative coil terminal several times while holding coil wire close to ground. This has to produce a spark. If it does but not while trying to start then in the distributor module is bad OR distributor not properly grounded. Distributor case MUST be grounded.

[Dusten]

8 minutes ago, datzenmike said:

With ignition on a test lamp should light dimly if touched to the negative side of the coil. Shows power is present and coil primary is good.

 

With ignition on touch a grounded wire to the negative coil terminal several times while holding coil wire close to ground. This has to produce a spark. If it does but not while trying to start then in the distributor module is bad OR distributor not properly grounded. Distributor case MUST be grounded.

 

 

Ok I'm not getting spark when grounding the coil.  

 

When you say distributor module you mean the hei or in the distributor? 

 

I doubt the dizzy magically lost ground.  But you never know.  

[banzai510(hainz)]

i think there is a way to ck the magnet ring pick up then next is the module. But IM sure you know this already.

[datzenmike]

2 hours ago, Dusten said:

 

 

Ok I'm not getting spark when grounding the coil.  

 

 

 Then one of two things...

 

1/ you don't have 12v on the positive coil terminal

 

2/ the coil primary windings are broken somewhere. You said you changed the coil so not that. See 1/ above.

[Dusten]

3 hours ago, datzenmike said:

 Then one of two things...

 

1/ you don't have 12v on the positive coil terminal

 

2/ the coil primary windings are broken somewhere. You said you changed the coil so not that. See 1/ above.

 

I ohm'd out both coils.  The windings are Good.  

 

I'm pretty good with a meter.  It's part of my job.  I have 12v.  The trucks at work.  So I can't do anything until I get back.  I'll shoot some videos tonight fiddling with it.  

 

[bilzbobaggins]

OE wiring between the modules, coil and distributor?  I chased something similar down and had a failed wire between coil and module.  

[Dusten]

44 minutes ago, bilzbobaggins said:

OE wiring between the modules, coil and distributor?  I chased something similar down and had a failed wire between coil and module.  

 

 

I'll know more after it gets home.  I got to work tonight and threw my good lithium ion jump pack on it and fired right up.  I parked it at a friend's and got a ride back to work.  

[datzenmike]

If it fired right up with a boost then maybe voltage is low on the coil or enough that the HEI module won't trigger.

 

If 12v on coil positive and you ground and release the coil negative, it must spark if the coil is good. Once this is confirmed then we move on to the HEI module and wiring.

[Dusten]

18 minutes ago, datzenmike said:

If it fired right up with a boost then maybe voltage is low on the coil or enough that the HEI module won't trigger.

 

If 12v on coil positive and you ground and release the coil negative, it must spark if the coil is good. Once this is confirmed then we move on to the HEI module and wiring.

 

That's my thought.  Low voltage.

 

When you say spark, you mean the coil should fire and I should see a spark off the coil wire? 

[Dusten]

So as an aviation mechanic and backyard mechanic I often tell people that when you have a problem creep up go back and look at the last couple things you've worked on and see if something you did previously could be at fault.

 

About a week ago I decided to throw a new battery in the truck due to an unknown age of the old battery wheat cranking and winter coming up.

 

Today I went to start the truck in my driveway so I can move it into the garage and work on it and it cranked over extremely slow. I knew this was odd because the battery was brand new, I popped the hood and went to check voltage on the battery and realized the ground cable on the battery was loose and hot. So I had a ground issue. This would lead to slow cranking when it was cold so it wouldn't fire over it would lead to a voltage drop to the coil which wouldn't spark during cranking and basically all of my problems.

 

I tighten the negative cable up and the truck fired right up.

 

In the process of all of this I decided to look into the ignition system and make sure I had everything squared away. I found the factory transistor box in a box of parts that I got with the truck and all of the wiring was still in place, so I removed the HEI module and reinstalled all of the factory ignition.

 

The truck fired off and runs like a champ