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Internal short in distributor?

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Old 09-30-2012 | 07:32 PM
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Default Internal short in distributor?

I've been having a very weird issue lately trying to get my truck to start. The engine hasn't run in a few years, and I'm trying to get this beast on the road again.

Anyways, I can not get my engine to properly spin. It is a very slow spin, similar to a low voltage spin from the starter. Now, I can get rid of this symptom and have the engine spin like I just installed it from a crate, but to do this, I need to open the circuit in the distributor. If I disconnect the battery wire from the dist. the engine spins like normal. If I disconnect the 3 wires that come from the base of the dist. it spins like normal. But while it spins without being fully connected, I get no spark.

When I do have spark, it is a very strong and bright spark... but it is super slow to turn. I don't know where to look in this. This is a new rotor, and cap, and i replaced the coil with one of the 3 in my garage. I replaced almost all the internals as well with no change.

What is causing my short as soon as I energize the coil?
 
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Old 10-01-2012 | 08:34 PM
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Wow... nothing? That tricky of a question?
 
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Old 10-02-2012 | 05:23 AM
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Might have something to do with the complete lack of vehicle information. Or the fact that your title and assessment of the problem are WAY off base and confusing matters. That doesn't mean you should 'bump' the thread such as you have... Did you really sit on you thumbs for two whole days?

My guess would be that nothing is shorting out and that your timing is way too advanced.
 
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Old 10-02-2012 | 06:54 PM
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Sorry. I forgot that I post on a different forum and have all my info in my signature.

79 Jimmy, chev 350, TH350.

Now, as for the issue I had posted, I had given it a title for a reason. If I disconnect any wire from the distributor, the engine turns over at a normal rate. Once the circuit is completed by plugging all the wires in, the engine barely turns over, if at all. Acting like low voltage to the starter.

I have adjusted the distributor from one side to the other (1/8 turn at a time) and it makes no difference. I currently can not get the engine to run.

As a side note, I only bumped it as no one had responded. How was I to know that my question was confusing to others without someone telling me? As for my last 2 days, I have been reading as much info as I can about the issue. How to properly check the coil, wires, everything. Staring at wiring diagrams as well. But, since the truck is not sitting in my garage, but a 30 minute drive away, no I have not done anything to it yet.

But thanks for the actual reply.
 
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Old 10-03-2012 | 11:35 AM
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Vehicle that has been sitting for a few years needs more than a cap and rotor. That's one of the items that I'd probably replace last as long as it has not been exposed to the elements it should fair well over the years.

I'm assuming that since you replaced the coil with an extra in your garage we're not talking about a HEI system?

Something you should look at are the:
Fuel in the tank, old fuel, especially that has sat for a number of year, will run like $h!t. Plus all the ethanol that is in there has eaten away the rubber seals in your carb and has dissolved the rubber fuel lines gumming up the filter and whatever passages were still open in your carb.
Spark plugs, have you looked at your spark plugs? I'm guessing they weren't replaced right before mothballing it....
Battery, are you taking a new battery with you?
Mice, have there been any mice living in your ride? Is it parked in a barn? They can chew on the wires and make themselves little nests to be nice an comfy throughout the winter... leaving you with a smoking pile of parts when you actually do get it running and energize the electrical system for an extended period of time...

What you are saying about the draw from the distributor makes very little sense to me, I don't know that it would take that much power away from the starting system, or at least enough to make it crank slowly.

My best advise would be to try another distributor. If you think that is where the problem is replace it. If it isn't the problem at least you know to look at the rest of your wiring.
 
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Old 10-03-2012 | 08:57 PM
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As much as i would love to say that it has been sitting for a while, only the truck has. I recently dropped a different engine in the truck and have been trying to get this to run. The engine had only sat for one year, and ran perfect when it was garaged.

I am talking about an HEI system actually, I switched the coil that sits on top of the distributor cap, and the internal modules. My next step was to be replacing the entire distributor as a last chance effort.

The spark plugs are new, batteries have been tested and are less than a year old, and there are no mice.

I was given the suggestion to try jumping from the battery lead wire into the distributor directly to the battery. Sound like a good idea?
 
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Old 10-03-2012 | 10:58 PM
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One thought I keep have pop into my head is when you said 'when you hook up the wires to the distributor it cranks slowly'.
Have you traced those wires & made sure they're not pinched or grounding out somewhere, connections fore & aft are ok as well?

A test could be is you turn the headlights on & notice their brightness without those wires hooked up. Then hook the wires up & turn the headlights on. Any difference?
Try it with the key off & key on (run position) for both tests.

Odd, but I have to ask - is the distributor installed 180 degrees out?
 

Last edited by Rottidog; 10-03-2012 at 11:01 PM.
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Old 10-04-2012 | 07:23 PM
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I have traced the wires back and none are pinched. I've replaced wires that looked a little brittle and ran new full length wires on those (not just splicing a section to make it visibly better).

I will try the headlights test. I assume this test is to see if the draw is at the distributor or just a test for a draw of power somewhere?

I have been asked and now question myself if the distributor isn't 180'd. When I installed it, I turned the engine by hand with the valve cover off and dropped it in on tdc on the compression stroke for cylinder 1. I might take the damn thing out just to verify that it isn't.
 
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Old 10-04-2012 | 10:10 PM
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Cudo's on replacing the wires, at least you know those are good!
The headlight thing is to see the power draw. Wires unhooked, key ON position - look at the lights. Try the same with the key OFF
Do the same with the wires hooked up in both circumstances & see if there's a difference.
If there is, with the key ON & wires hooked up - you have a ground short issue robbing power & possibly a fire.
With the key ON & no wires hooked up - you look at the ignition circuit.
In the OFF (wires hooked up or not) position you can rule out ignition switch issues if the headlights stay the same.

(light bulb) How are the wires at the starter solenoid? All hooked up properly?
 
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Old 10-04-2012 | 10:31 PM
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Yes, the starter solenoid were hooked up properly. That has been double, triple, and quadruple checked. That was actually one of the wires that I replaced was ignition to solenoid as i had fried that one a few years back and it was really redneck spliced together. I have also replaced the starter in that truck enough times now, that I can do it in my sleep. The starter haven't been bad, I've just had them tested and tried eliminating this problem one by one.
 


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