No spark- trouble shooting electronic ignition

D

dave silva

New member
Oct 2, 2009
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Not sure which Electronic ignition i have- it's red, looks like any one of several on Amazon for around $60.

I have no spark. i have power to the distributor.

Looks good inside, no obvious dirt or damage. Unit is seven years old with less than 2000 miles.

Should i just replace it?

Or is there any additional trouble shooting i can do?

--
Dave & Ellen Silva
Hertford, NC

76 Birchaven, 1-ton and other stuff

Currently planning the Great american Road Trip Summer 2021

It's gonna take a lot of Adderall to get this thing right.
 
This brings back memories from last summer blocking traffic with my gmc 1800 miles from home....

Most should agree on no spark-

Check connector and power to distributor.. you did that.

Next it is usually module. You can pull that out and auto parts places can test.

Then it could be coil.

7 year old cap and rotor should be replaced anyhow. It could also be the cap/rotor. But more unlikely.

Last summer I got towed
To autozone. I pulled my module out and had them test it and it tested fine.

I then bought a cap, coil and rotor and module.

I installed the old module, and then installed new cap, rotor and coil. And it fired up.

When I git home, I bought another distributor. As I learned that if my module, and coil were not the problem the next item would be the “pick
up”. I would rather swap out an entire distributor at that point then have to mess with changing just a pickup coil on the road. The
distributor also makes a nice storage device for my new module, and now my new coil and rotor.

So I ended up bring towed a mile. Aaa paid the $300 for that, but ended up loosing a hour or 2 for towing, over less then $100 of
parts(coil,cap,rotor) And about 15 minutes to swap.

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
What year is your coach, as 73-74 had the old point and condenser system.
If you have the later with the large cap with internal coil, We suggest
you change both the coil and the module.
We have found that it is better to get the more expensive module as it
lasts longer.
also get the jell and put it on the bottom of the module for heat transfer.

> This brings back memories from last summer blocking traffic with my gmc
> 1800 miles from home....
>
> Most should agree on no spark-
>
> Check connector and power to distributor.. you did that.
>
> Next it is usually module. You can pull that out and auto parts places
> can test.
>
> Then it could be coil.
>
> 7 year old cap and rotor should be replaced anyhow. It could also be the
> cap/rotor. But more unlikely.
>
> Last summer I got towed
> To autozone. I pulled my module out and had them test it and it tested
> fine.
>
> I then bought a cap, coil and rotor and module.
>
> I installed the old module, and then installed new cap, rotor and coil.
> And it fired up.
>
> When I git home, I bought another distributor. As I learned that if my
> module, and coil were not the problem the next item would be the “pick
> up”. I would rather swap out an entire distributor at that point then
> have to mess with changing just a pickup coil on the road. The
> distributor also makes a nice storage device for my new module, and now my
> new coil and rotor.
>
> So I ended up bring towed a mile. Aaa paid the $300 for that, but ended
> up loosing a hour or 2 for towing, over less then $100 of
> parts(coil,cap,rotor) And about 15 minutes to swap.
>
>
> --
> Jon Roche
> 75 palm beach
> EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
> St. Cloud, MN
> http://lqqkatjon.blogspot.com/
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
 
from his sigfile= he has a 76 birchhaven, so should be HEI. from prior posting's this was a coop restoration probably 7 years ago, so hence the
red cap.

The heat sync compound is a something for sure to mention. New Modules come with the compound, but about enough for one swap. so if you install a
new module, and keep your old one for spare, you have no heat sink compound. when I got home I bought some. (have been known to donate some of my
spare parts to others too).

so now I keep a tube of this handy:
https://www.amazon.com/gp/product/B0044NI2M2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
FWIW, I put a known operating module...that I took out of my distributor....in coach storage, and use the new module. That way I know I have a working
module IF I have a failure. I've seen/heard of to many new modules that were bad right out of the box. JWID
--
Larry
78 Royale w/500 Caddy
Menomonie, WI.
 
You definitely can turn a good module into junk if you neglect the heat
sink compound between the module back and the plate beneath it. I try to
use the genuine GM product if I can find it. Also, do not forget to provide
a ground path for the distributor. Dick Paterson includes a lug for that
purpose on his units, some of the other brands do not. It is important.
Jim Hupy
Salem, Oregon

> FWIW, I put a known operating module...that I took out of my
> distributor....in coach storage, and use the new module. That way I know I
> have a working
> module IF I have a failure. I've seen/heard of to many new modules that
> were bad right out of the box. JWID
> --
> Larry
> 78 Royale w/500 Caddy
> Menomonie, WI.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
 
So, a new HEI distributor should cover all the bases, right?

Related question, could a distributor/ignition problem mimic a fuel problem?

I drove it 100 miles RT so another member could help me with a transmission swap (ok, i helped him, thanks Tom)

All through the journey it went from running great to barely running. Sometimes it resembled a clogged fuel filter but we ruled that out.

Still, given the history the consensus was that it was fuel related.

I barely made it home with almost no power. this was a couple months ago. Today was my first attempt to deal with it.

--
Dave & Ellen Silva
Hertford, NC

76 Birchaven, 1-ton and other stuff

Currently planning the Great american Road Trip Summer 2021

It's gonna take a lot of Adderall to get this thing right.
 
My take on the ignition situation: I carry a known good complete
distributor, , ready to R&R the one on the engine. To me, that's a simpler
repair than replacing the maybe-bad module, especially on my Cad500 where
the distributor is at the front of the engine, not back where it's easy
to get to like on the Olds.

When buying modules, I prefer to get an AC one out of a junked car, being
sure it's got the 7 pins my system required. I figure the odds are in my
favor that the donor car was NOT junked because of a failed module. So far
I've won and they've worked when swapped into my running distributor;
that's how I always test them (always using heat sink compound).

> Not sure which Electronic ignition i have- it's red, looks like any one of
> several on Amazon for around $60.
>
> I have no spark. i have power to the distributor.
>
> Looks good inside, no obvious dirt or damage. Unit is seven years old with
> less than 2000 miles.
>
> Should i just replace it?
>
> Or is there any additional trouble shooting i can do?
>
>
> --
> Dave & Ellen Silva
> Hertford, NC
>
> 76 Birchaven, 1-ton and other stuff
>
> Currently planning the Great american Road Trip Summer 2021
>
> It's gonna take a lot of Adderall to get this thing right.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
 
Red? That’s aftermarket something! Assuming you mean the cap? I suggest you diagnose this to be sure it’s not fuel issue. Ign modules
usually are either good or bad. I say usually because heat related issues can come up. Do not test for spark by disconnecting a plug wire! This sends
coil to max voltage rise and stresses the module with back EMF. Get a spark tester at auto parts store instead. Other HEI things to look for are coil
ground wire, cracked rotor, bad contact button, fatigued pickup coil leads.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
I prefer to use a timing light to check for spark. It is very quick to hook up. zip tie the trigger on and if you have proper spark it will flash
pretty consistently, and easy to read. if you hook it up carefully you can run down the road with it and get an indication on the spark when a
problem shows up.

an entire distributor generally will take care of spark problems, but you are swapping too many parts at once, and may end up chasing problems. I
can change a distributor module quickly. a coil is not difficult at all. but the pickup in the distributor means taking the distributor apart, so
that is why I keep a spare distributor. I would not want to mess with pulling a distributor out unless needed on the olds powered GMC. The pickup
is one of the more rare ignition failures.

yes- fuel problems can mimic ignition problems. and vice versa. No spark is no spark. and no gas is no gas. whole different deal when you are
dealing with intermittent problems.

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
> yes- fuel problems can mimic ignition problems. and vice versa. No spark is no spark. and no gas is no gas. whole different deal when you
> are dealing with intermittent problems.

Yes, i'm a former aircraft electrician, i just LOVE intermittent problems.

But this is really making a lot more sense now. The behavior was sorta like fuel flow but every once in a while it would run like a raped ape for a
while and then resume sputtering and power loss. Today i was just going to move it around the yard and it refused to start at all, even with raw
gas down her throat.

So, a new distributor (be here Thursday) will probably get it running and hten maybe we'll find the other problems went away too.

--
Dave & Ellen Silva
Hertford, NC

76 Birchaven, 1-ton and other stuff

Currently planning the Great american Road Trip Summer 2021

It's gonna take a lot of Adderall to get this thing right.
 
There are 3 major components that fail on the HEI Distributor used on a 1976 455 engine used in a GMC, They are in order of probability. The module,
The ignition coil, and the pickup coil. I have never had to replace a pick up coil which is good since you have to remove the distriubutor and take
it apart to replace it. There is a procedure for metering the components, but carry spares and I always just swap them. First swap the module. If
that does not work I swap the coil. If that does not work I look for other things. One is the mounting screws for the coil. Make sure they are
tight and there is a ground wire under one of them. The ground connection wire needs to be tight. Look inside the cap. Look at the center
connection for the rotor and make sure that the button is not worn away or missing.

Finally the main ground connection for the distributor is the mounting of the aluminum distributor to the steel engine. Over time that bi-metal
connection will corrode and not make a good electrical connection. Take out one of the vertical screws that goes from the inside through the bottom
and replace it with a longer one. Now you will have a vertical stud sticking out of the bottom. Attach a 16 to 20 gauge wire to the stud with an
added nut. The attach the other end of the wire to any bolt (except valve cover) on the engine. This added wire will bypass any corroded connection
the distributor mounting might have.

About the only other thingt I can think of is check the wire from the module that flexes when the distributor plate moves and see if it is possibly
broken. I have only seen that happen once.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
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