Cannot get spark through distributor?

Tiny
JRCHILDREE88
  • MEMBER
  • 1988 DODGE TRUCK
  • 5.2L
  • V8
  • 2WD
  • AUTOMATIC
  • 500 MILES
I have a 1987 Dodge D250 with a 5.2l engine and a Torqueflite 727 transmission. I have a new distributor with the vacuum advance and my spark tester shows I'm getting a blinking light showing the coil is firing but when I connect to distributor no matter how much I move distributor I can't get a spark through the spark plug wire.
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Monday, August 8th, 2022 AT 7:56 PM

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Tiny
CARADIODOC
  • EXPERT
All a blinking light tells you is you have something, but not necessarily enough voltage to fire a spark plug. Take a look at this article first:

https://www.2carpros.com/articles/how-to-check-for-ignition-spark

then check for spark by unplugging the coil wire from the distributor cap and holding the end about 3/8" from a valve cover or some other metal part of the engine. If you have to hold the wire to maintain that spacing, I prefer to use an insulated tool or piece of wood to prevent an accidental shock. When a helper cranks the engine, you should see nice blue, crisp sparks, four per engine revolution, and hear a loud snap each time.

If you don't have that strong spark, I'll need to know which ignition system you have. The base system uses a five-pin ignition module, (only four wires go to it), mounted on the right inner fender or on the firewall. The higher ignition system uses a computer bolted to the air filter housing. That one has the mechanical and vacuum advance built into it, so it uses a distributor without those timing advance systems on it.

I also need to know the symptoms or the problem you're trying to solve. A common failure is a crank / no-start, and another is the engine will start and run only as long as the ignition switch is held in the "crank" position, then it stalls as soon as the switch is released to the "run" position.

There's a two-wire connector for the distributor. It will have a black wire and an orange wire. Tell me if your distributor has one or two of those pairs of wires.

If you do have strong spark on the distributor wire, plug it back in, then do the same test at one of the spark plug wires. Unplug it from the spark plug, then stick a screwdriver into the boot to contact the terminal. Place or hold the screwdriver so there's a 3/8" gap to a metal part of the engine, then have your helper crank the engine. You should get a nice loud snap once for every two crankshaft revolutions.

Let me know what you find.
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Monday, August 8th, 2022 AT 9:12 PM

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