Automotive question has me stumped...

[CathyInBlue]

I have a 1994 Chevy Astro that won't start. It's not the fuel pump or injectors, so it's not a fuel delivery problem. I started on the ignition system by siccing a spark tester on all of the leads off the distributor. The only one that sparks is the one from the coil pack. How is that possible? Is the rotor shorting through its shaft to the block?

The cap has been soaking in dilute vinegar all night. I'll reinstall and see what's what in the morning. If it doesn't work, I'll just replace the rotor and cap. They're cheap, and the rotor has plenty of carbon build up on it.

 

[gregtheplumber]

if you have spark from the coil but not from the plugs is probably a bad cap

 

[threefiftyfour]

I have seen carbon trails through a rotor to ground. That is the likely cause.

 

[Bunnykid68]

Astros from that era are notorious for cap and rotor wearing prematurely. I replaced mine 6 times, but I also had 432,000 miles on it. I am of course assuming it has the 4.3 Votec.

 

[CathyInBlue]

4.3 it is. I'll get a new cap and rotor pronto if this doesn't work in a few hours. I already pulled an loose air filter hold down stud out of the throttle body where it had stuck the throttle wide open once. I think this van is cursed.

 

[Rocket]

With the cap off can you turn the rotor? If the drive gear is broken or sheared the roll pin the rotor would not turn and would not distribute spark. This happens more often on fords but you never know. Good luck

 

[CathyInBlue]

No. The rotor only turns with the shaft, but the contact cup on top has lots of carbon build up. I'll wipe it down with IPA before I button it back up.

 

[Leo]

I am unfamiliar with the chevy astro series of cars. Can you check to see if the cam/distributor is in time with the crankshaft. A broken timing gear is not out of the question. It used to happen to the fibre cam sprocket on V-8 chevys all the time. It also happens on engines with a timing belt.

 

[karl77]

sounds like a bad cap/rotor. would change them and see what happens.

could also be a bad module in the distributor.

 

[Dead Duck]

1994 Chevy Astro

I know your problem. Just change these 3 things and your good to go -

- The Year
- The Make
- The Model

Easy Fix!

 

[hopper68]

Put spark tester going into cap, should flash repeatedly while cranking.
If yes try on plugwires.
power in but not out says problem is cap and rotor

Usually when a ignition module goes bad in one of those the van will die going down the road and restart after it cools down. Just for future reference.

 

[CathyInBlue]

That's exactly what I did. Spark on the coil wire, none on the plug wires.

 

[ThrottleJockey]

I think there is a pick up coil near the bottom of the shaft that the distributor is attached to. Real PITA to get to as the entire distributor assembly has to come out. They are known to go bad. Ignition module is a very common problem with all GMs from that era (fords too). Both could cause this problem. Another issue with GMs from that era is that they used a nylon timing gear and they tend to strip off over time, this could also cause your problem. I don't think that 4.3 is an interference engine so if it is the timing gear you should be in pretty good shape. I'm no expert, but I did own an auto service and repair shop from '93-'96.

 

[eldirector]

You can check the cap and rotor with an ohm meter. Should have continuity on the rotor from the center tab to the tip, and should have continuity on the cap from the inside of each "post" to the outside. It would be rare to have all 6 posts bad at once, but burning through the rotor's single contact is possible.

My guess is the ignition module, though. I can't remember how to test them. But running fine one day, an dead the next just doesn't sound like cap/rotor to me.

Best of luck!

 

[Suprtek]

I agree with others that have said cap and rotor. In a situation like that, I'd probably just replace the cap, rotor, plugs and plug wires all at once while I was in there. Unless of course you know for sure they are all recent parts. I wouldn't waste time trying to salvage an old one. I can also confirm what has been said about these vans being notorious for ignition/spark issues. You may have also noticed a check engine light at times before it stopped running, especially in wet conditions. Good luck and keep us posted.

 

[deanwirth]

Did you change the cap/rotor yet? Sounds to me like thats the problem. likely too much gap/carbon buildup or its carbon tracked and grounding out.

 

[halfmileharry]

A good possibiity is the Computer box. I had 3 on mine in 5 years. You can't even get a correct problem code when it goes bad.
I only changed cap and rotor once at a scheduled tune up.
Guessing and random parts changing is as low tech as it gets. Try to get a code reading and go from there.

 

[ThrottleJockey]

A good possibiity is the Computer box. I had 3 on mine in 5 years. You can't even get a correct problem code when it goes bad.
I only changed cap and rotor once at a scheduled tune up.
Guessing and random parts changing is as low tech as it gets. Try to get a code reading and go from there.

This will likely only lead to replacing a WHOLE bunch of electrical components/sensors before you get to the one that is bad. Codes will only tell you what system is failing, even when they give a specific sensor, it is only the first in the series in that system. Remember, it's a '94? OBDII. A dealership can get away with that since they just put the parts back on the shelf when they fail to resolve the issue, for us backyard types we don't have that luxury since we cannot return electrical components once they've been installed and they get EXPENSIVE. I've been burned this way far too many times.

 

[Rocket]

This will likely only lead to replacing a WHOLE bunch of electrical components/sensors before you get to the one that is bad. Codes will only tell you what system is failing, even when they give a specific sensor, it is only the first in the series in that system. Remember, it's a '94? OBDII. A dealership can get away with that since they just put the parts back on the shelf when they fail to resolve the issue, for us backyard types we don't have that luxury since we cannot return electrical components once they've been installed and they get EXPENSIVE. I've been burned this way far too many times.

A 94 is OBD1 a much harder sys to diagnose.

 

[CathyInBlue]

The battery's deader than Osama bin Laden, modulo the being at the bottom of the Indian Ocean thing. I couldn't even jump the Astro to life. Turning the ignition key just gets the click of the starter solenoid and a half-hearted groan as the crank shaft turns a little bit. Took the battery to Vatozone to confirm that it's terminal. Still, it should have started while being jumped from my car. Wondering now about the starter motor cables. I have another set I'm gonna bolt on and try when it's dryer. After that, I'll wonder about the starter motor itself.

It had started getting sluggish at cranking before I took the distributor out to clean it, so this is not exactly new.