Last post on Apr 30, 2013 at 10:37 AM
You are in the GMC Safari & Chevy Astro
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Chevrolet Astro, Fuel System, Van
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#21 of 210 Re: no start problems continue... [fixitrod]
Dec 18, 2006 (8:59 am)
My post was full of advice on what to do.
Please read it again:
"Your spark is too weak. I checked the spark on my 2000 Explorer at terminal #1 of the coil pack, and it threw hot blue/orange sparks up to 1 1/2 inches long. I think your less than 1/2 inch sparks is only good for a lawn mower. You had better check your manual to see how to check and test the ignition system.
If you can't find the problem, you can pull the cap and rotor, or maybe just pull the whole distributor out and take it down to the Autozone Store and let them test it. They can test the module, the pickup coil and the coil output. Does yours have the coil in the distributor cap?
Here is the link to the Autozone repair info for the HEI ignition, it has a lot of information:
http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1- - 1/7d/1e/0900823d80117d1e.jsp "
#1 I said to Check the information at the Autozone website link that I posted, it has ALL the information that you need to check and diagnose the problem.
#2 I said to Take the distributor down to the Autozone Store and let them check it, because they have the testing tools to check the PICKUP COIL, check the MODULE, and to check the IGNITION COIL.
#3 You are checking the resistance of the wires and such, but you need to make sure the system components are working correctly to be sure the coil is putting out the Hot Spark that it is supposed to put out, over 40,000 volts. The specific components that need to be indivually tested are:
A. The PICKUP COIL.
B. The MODULE.
C. The IGNITION COIL.
The components can be tested with an ohm meter to see if they are in spec, but they need to also be tested with the proper electronic testers to be sure that they are performing properly. Then, the assembly all put together needs to be tested for total output. The Total Output Volts should be over 40,000 volts, there is a tool # J-26792 for testing the coil output.
The best thing to do with it is to pull the distributor out and take it down to the Autozone and let them check the whole assembly. Just be sure you have it properly in time when you reinstall it.
#22 of 210 Re: no start problems continue... [fixitrod]
Dec 18, 2006 (9:01 am)
Did they put a new serpentine belt on it?
#23 of 210 Re: no start problems continue... [electricdesign]
Dec 18, 2006 (3:58 pm)
I think I responded before I got your last post which as you say was chunk full of good info. Three autozones I called do not test distributors and one mechanic I was referred to says he needs the van..imagine that.
I tested the pickup coil by (fig 12 on the auto zone site) and according to fig. 13 it needs replacing. I gave a spark with the 4terminal connector dosconnected and as well I found the new rotor I had put on after the no start problems started was also cracked...hmmm.
The testing of the voltage of the ignition module has me confused No 4"Check volts at "+" and "C" and should I probe both together or probe one and apply the other lead to ground. When I did both methods I got less than 1 volt with the KOEO which indicates to repair wire from module. These two wire swhich connect the Ignition module and the new ignition coil showed .001ohms continuity. Does this appear too low?)but they are not open. I need to do step 5 in fig 13(hopefully my spark plug testor can suffice as a test light?)
I did not change the serpentine belt when I changed the pulleys ...think I need to?
#24 of 210 Re: no start problems continue... [fixitrod]
Dec 18, 2006 (8:42 pm)
I'm surprised by the Autozone, I apologize for recommending them, I had ignition checked on an HEI distributor years ago, but it may have been another store, they have changed names of the stores around here. Discount is now Advanced and One-Stop is now Bumper to Bumper. I called the Autozone here in St Pete and they said they can only test the module, it has two screws, you take out the module and take it to them and they can test it. I would do that, and then test the magnet at the pickup coil. If the magnet gets weak, it can make the fire weak. You can lightly touch a small metal screwdriver blade to the poles pieces and feel for magnetisum. As far as testing the spark output voltage, the easiest way to do that is by "drawing an arc" like I desctibed before. The longer the arc, the higher the voltage, but be sure to have the battery charger on the battery when you are cranking the engine, because low battery volts will make low spark volts. I would think that if you can draw out an arc an inch or longer while cranking the engine, that should be good. A rough rule of thumb is the voltage is about 10,000 volts for every quarter inch. So a one inch arc should be about 40,000 volts.
About your question: "The testing of the voltage of the ignition module has me confused No 4"Check volts at "+" and "C" and should I probe both together or probe one and apply the other lead to ground?"
Your question is about Figure 12 steps 3 and 4. If you look in FIGURE 11, it gives you the answer. Those + and C wires go from the module to each side of the coil. The coil is fed "Hot" from the ignition switch and that same connection goes to one side of the coil and also to the "+" wire. Therefore the "Hot" wire from the switch feeds one side of the ignition coil and also the "+" wire, which feeds power into the module. This means the "+" wire should always show power when the ignition is on, I would assume it should be near battery voltage. The test says it should read above 10 volts, with the connector unpluged, measure from the "+" to ground with the key on for your reading.
The "C" wire goes from the module to the other side of the coil from the power connection. This tells me that this is the wire that "Fires" the coil, by electronicly grounding at the instant the coil is suppose to fire. Everytime this wire grounds and then opens, it lets current flow through the primary of the coil, the coil builds up a magnetic field, then the instant the wire is opened (switched) by the module, the magnetic field around the coil collapses and creates the high voltage in the secondary coil. The module is an electronic switch that switches the "C" wire to ground On and Off. So to test the "C" wire, with the ignition on and the connector unpluged measure from the "C" wire to ground with the key on for your reading. The test says it should be over 10 volts. The voltage you are reading is what is coming through the primary winding of the coil. With no load on the circuit, the voltage you read should be the same or very close to the voltage you read on the "+" wire.
What you are calling in fig 13, step 5 is step 4. Connect a 12 volt test light between the Tach Terminal and ground. The Tach terminal is exactly the same connection as the "C" wire, the "load" side of the coil. They call for the light to be steady when you crank the engine, to verify that there is no votlage drop across the primary coil as it is firing. If there IS blinking of the light, that means the primary has voltage drop everytime it has load placed on it, which means the coil is bad. An ordinary 12 volt test light will work for this, the most common electrical tool that there is.
About the serpentine belt, the belt on my 97 used to make noise and would slip a little when it got wet, yet it looked ok. I put on a new belt, the the difference was like night and day, it's been perfect now for 4 years, no noise, no slip.
#25 of 210 Re: no start problems continue... [electricdesign]
Dec 19, 2006 (3:09 pm)
Well: I went through the guidelines in fig 13(fig 11 is for the 4cylinder) and approached from a "no spark" as oppossed to low spark because in box No.1 it says..."a few sparks and then nothing is considered no spark." Got a big spark from the ignition coil even with insulated tools. Reolaced rotor that was cracked. Got more than 10 volts from "c" and "+" but got 1-10 with tach lead to ground which indicates to replace module. Well I took your advice and had mine checked and it passed so I'm thinking maybe passing still does not mean able to do its job fully but I regreased mine...frustratted at this point and thinking of just getting a new distributor but I continued to put the parts back to gether and redo some of the tests. Specifically the crank test in step 4 fig 13 and the engine sounded like it wanted to turn over. I hooked all the wires back up and doggone if it didn't start. Purring like a kitten. God only knows cause I don't.
Now mind you I had started pulling wires off to take off the intake plenum so it ran with the TPS and MAP sensors disconnected and I think it caused some codes; the Chk engine light is on now so I hooked them back up but the light is still on. I'll watch this. I did have a couple of plug wires crossed and after rearranging them the engine smoothed out. The saga continues but for now I see a bit of light....Thanks so much to you my friend. Oh; got a drive belt for the wifes' V8 Explorer.
#26 of 210 Re: no start problems continue... [fixitrod]
Dec 19, 2006 (8:16 pm)
Figure 11 is for the 4 cylinder engine, but the electrical drawing is the same, the pickup, module and coil and wiring is basicly the same for all of them.
I know why the engine started, it's because of one of two things:
1. either because you replaced the cracked rotor (it could have been leaking off the high voltage)
2. or removing the module and replacing it could have cleaned and refreshed it's connections (it could have had resistance or corrosion in the connections to the module).
Wow, So ends the Saga of the GMC Safari Van that wouldn't start! That was quite a lot to go through to find that problem, as we have been at this for over a week it seems? I'm glad the effort paid off, I was sure it would start, I was just hoping it would start before Christmas, So let this be a Christmas present to you! Stay in touch.
Merry Christmas & Happy New Year,
from Electric Designer In Sunny Florida
#27 of 210 Re: no start problems continue... [electricdesign]
Dec 20, 2006 (8:12 am)
I would agree that refreshing the connections make sense because out of habit a cleaned them a little with a screwdriver before putting it back together. The cracked rotor also as well possible.
Wow is right but I sure learned a lot and goes to show two heads are better than one. I need to do a top end clean of this van but I am glad you suggested I hold off on the fuel investigation. I am hoping that by having the intake and throttle body extension off while running the engine is what gave those TPS and MAP sensor codes and that once I get everything put back together they should reset. I'll check those circuits anywaay just to be sure.
Hows your residential electrical? I get the idea you're an electrician. I need to install a couple of outlets in the new basement. Do they have a forum for that? I amrodslackmindspring.com if not.
Happy Holidays to you and yours!!
#28 of 210 Re: no start problems continue... [fixitrod]
Dec 20, 2006 (9:35 am)
Your Welcome and Merry Christmas
#30 of 210 95 safari no start problem
Dec 23, 2006 (4:14 pm)
i have a 95 safari that just quit. it will turn over but wont start. replaced the feul pump and steering column checked the fuses and pump relay. now for the funny part everything works execpt for the fuel pump head lights and interior lights. did a test on the wiring at the back of the fuse block and found that a fuseable link wire was testing as grounded. if i jump power to the fuel pump fuse it will start any ideas would be nice as it is my grandparents van and they are handicapped thanx