86 BRAT weak/no spark

[SiriusBlack]

Hey all, I have a 1986 BRAT that has had disty trouble most of its life it seems. It original disty went bad an a different one was swapped in from a parts wagon. Then that one went bad and it got the disty from another parts car. This third disty was from an older model and had some sort of complicated ignition module bolted to the top of the coil.

Now I was finally able to track down a cardon rebuilt disty, I installed the new disty, new accel coil, new premium blue NGK plug wires and new NGK plugs. I put all of it in and it won't start. No spark from coil. There is 12 volts at pos and neg. We get a weak spark if we ground the coil neg to a body ground. Otherwise no spark at all.

Any help would be appreciated

Thanks in advance.

 

 

 

 

 

 

 

[Dee2]

Seems unlikely that all the distributors would be bad.  So I'm going to assume that's not the problem.

You have a new coil, plugs and wires.... what about the wire between the coil and the distributor ?

Quote

We get a weak spark if we ground the coil neg to a body ground. Otherwise no spark at all.

A weak spark from the plugs or a weak spark from the coil ?

There's some specific tests outlined here chapter 9 troubleshooting for coil/plugs/ distributor.  See if there's anything there that you may not yet have tried.

http://www.suberdave.com/USMB/HTKYSA.PDF

[SiriusBlack]

@Dee2 When we ground the neg contact on the coil, the ground wire we're using sparks strong. If we hold the new coil wire to a ground and ground the neg post we get a weak little spark from the coil wire.

Replacing the distys usually fixed the the issue. I assume we went through 2 because they were used ones we pulled off parts vehicles.

Edited April 4, 2021 by SiriusBlack

[Dee2]

8 hours ago, SiriusBlack said:

When we ground the neg contact on the coil, the ground wire we're using sparks strong. If we hold the new coil wire to a ground and ground the neg post we get a weak little spark from the coil wire.

I would skip the extra ground wire and simply hold the coil wire (use insulated pliers) next to a ground surface while someone cranks the engine.  See procedure from link provided above.

If you get a good spark then the coil and coil wire are good.  If not then one of the two is bad.

That would lead to the next step, the distributor.  Are you changing the cap with each new distributor install or are you using the same cap ?

[Rampage]

Hook the volt meter to the Pos. 12 volt side of the coil. When you ground the Neg. terminal of the coil, does the 12 volts stay or drop?

[SiriusBlack]

14 hours ago, Dee2 said:

That would lead to the next step, the distributor.  Are you changing the cap with each new distributor install or are you using the same cap ?

I have been using the caps that were on the distys I pulled. The new disty has the old cap from the last parts disty.

[SiriusBlack]

18 hours ago, Dee2 said:

would skip the extra ground wire and simply hold the coil wire (use insulated pliers) next to a ground surface while someone cranks the engine.  See procedure from link provided above

We did that first and got nothing. We can only get a spark from the coil wire if we ground the coil neg as well.

[Dee2]

4 hours ago, SiriusBlack said:

We did that first and got nothing. We can only get a spark from the coil wire if we ground the coil neg as well.

Something is clearly wrong there.  Perhaps the grounding, the coil or the coil cable.  But at least you know where to focus your efforts.  You can take the coil in to a shop and have it and the wire tested.  If they check out then you have a grounding problem.

You can also verify if it is the right coil for the vehicle.  Maybe they gave you the wrong one (?)