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Weak spark (orange glow) on late model pickup truck Answered

So  I have a 95 chevy C-1500 5.7 V8,
Been having some progressively worse problems with it running rough and hesitating when accelerating.

I will be re-timing it soon but that is a separate issue for the moment,

When I tested the ignition system I noticed the spark tester was glowing orange/red instead of blue. (I can't even get my timing light to fire)
It was due for new plugs and wires so I replaced both. The Ignition coil is less then a year old and I just finished replacing the Rotor and distributor cap. Still have an orange spark.

I really need to fix this before I can time it, Any Ideas?


Josehf Murchison

2 years ago

How old is the ignition module. (Points under the rotor and the points module, they use electronic points now.)

Quite often if that is weak you will get a weak spark.


2 years ago

Make sure you're getting decent primary voltage to the coil, 11.5v to 12.4v.

Possibly the condensor across the points is shot.

Using the Downunder35m method with a spare plug against the chassis, manually interrupt the voltage to the coil by pulsing the +1 terminal to the distributor, to chassis(ground), obviously with a jumper wire.

You should get a nice blue spark if all is well.


2 years ago

IMHO these testers are only good to check if there is a spark at all but not to actually judge the voltage or power of it.
I had total bogus showing both with brand new coils and coils that did not even manage to run above the mid rev range.
Since then I reverted back to the old ways and either use a spark plug against the engine or if I find it quick enough a clear pencil I made up as an adjustable spark gap.
An orange color usually indicates a quite strong spark while a slim blue one indicates the lower to normal operation depending on the system.
In the pen I also have a tiny window cut out that allows to hear the spark - for me the best test as a loud sound always means lots of power while a slight ping means something is bad.

Since you don't really know where your culprit it and most things are new now anyway I suggest to test the ignition coil in a different car or with a test circuit.
Heat and vibration ca cause hairline cracks that you won't see with the naked eye unless you are lucky and the light is right.
Old systems love to fool you into buying all sorts of new things to fix them and most people overlook the cheapest part: The capacitor on the side of the dizzi!
If that one is faulty or near to giving up it can mess with your ignition as well as turning your radio into a rev counter.
Some of these systems either require a resistor in the rotor or so call resistance leads to the spark plugs.
So it pays off to know or measure the rotor - dead short on the original means a standard replacement.
No continuity or a high resistance on the original means a rotor with resistor is required or as an alternative leads with resistance instead of the standard copper ones.
The resistance ones usually have a carbon fibre core.
Last but not least: For you tests, did you make sure the weather is good and the beer cold enough?
Warm beer can mess with your results! ;)