Continuation of the "I hate GM" thread. - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

Reply
 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 09-07-2005, 12:22 AM Thread Starter
 
Join Date: May 2001
Posts: 3,501
Thanks: 0
Thanked 0 Times in 0 Posts
 
Continuation of the \"I hate GM\" thread.

I'm going to try to lay this out nice and simple.

Occurance: Backing up in the driveway after cranking the exhaust on and sealing it up. The Jeep sputters and dies.

Problem: Got Fuel, Got Air, nogo on spark.

Swapped the coil - No change
Swapped the module - No change
Got an entire HEI dist. and dropped it into the engine.
This meant we had a different:
-Coil
-Modulator
-Pickup
-Capacitor (thing that plugs into the mod)
-Cap
-Vac Advance

We have also wired 12V straight from the battery to the Coil "BAT+" terminal.. So the Distributor is getting 12V.

And we have cranked the engine with the cap off, and observed the rotor turning.

Have also tried the cap on at what we belive is "0", "180", 195, 165, 15, 345.

Now, we get 1 spark.
That's right. 1 spark.
Every time you crank the engine. 1 spark. (Oh, and from experiance, this spark has A LOT of get up and go!!)

If you crank, then crank quickly again, there's no second spark.

We have also had one REALLY loud POP.
and several noises that sound like escaping gas several seconds after the engine has stopped cranking.

I think this one spark thing is going to be key to the whole problem.

The only part that has not been changed at all is the Rotor.

But other then that I've tried:

3 Coils
3 Modulators
2 Pickups
2 Capacitor doohickeys
2 Caps
2 Distributors
1 Rotor

So, who can fix this.
I'm completely puzzled. I've literally changed everything to do with the ignition.. or so I thought?
It seems I HAVE BEEN SMITED BY THE CHEVY GODS [img]/ubbthreads/images/graemlins/frown.gif[/img]

Oh
Testing the Coils, and the pickups shows that all 3 are within the marginal limits. (resistance testing)
Infernozx is offline  
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 09-07-2005, 04:37 AM
 
Join Date: Feb 2004
Posts: 946
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Continuation of the \"I hate GM\" thread.

[ QUOTE ]
The only part that has not been changed at all is the Rotor.

[/ QUOTE ]

Ha ha, maybe the rotor is defective and the spark jumps to the distributor shaft instead of the plugs.

Sorry I can't be more helpful.
John_Strenk is offline  
post #3 of (permalink) Old 09-07-2005, 06:57 AM
I Might Just Know What I'm Talking About
 
Pete88YJ's Avatar
 
Join Date: Sep 1999
Location: BOSTON
Posts: 1,748
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Continuation of the \"I hate GM\" thread.

Any chance you lost your ground connection from the battery to the block? Gotta have - as well as +

Good luck.
Pete
Pete88YJ is offline  
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 09-07-2005, 08:19 AM
 
Join Date: Sep 1999
Posts: 5,383
Thanks: 0
Thanked 1 Time in 1 Post
 
Re: Continuation of the \"I hate GM\" thread.

1 rotor.
Does this mean you tried one extra rotor, or you have been using the same rotor? (or am I just reading impaired?)

Adding a ground is a good idea.
GM, like all the cheap companies, didn't dedicate a wire for the ignition ground.
Ground the heads while you are at it, so the plugs get good ground. Don't rely on the head bolts.

You may want to verify your timing chain (crankshaft TDC location).
The 305 was notorious for slipping teeth on the timing chain.
If you need instructions on verifying TDC, Balancer, Distributor location, let me know, I've got it on my web site.
Junk Yard Genius is offline  
post #5 of (permalink) Old 09-07-2005, 10:57 AM Thread Starter
 
Join Date: May 2001
Posts: 3,501
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Continuation of the \"I hate GM\" thread.

That info would be great TR.

As for the grounds.. I just ran new power, and new grounds to the starter/winch and so on. it's 1/0 from the block to the battery, and then ive got grounds from the frame to the block, and the body to the block. I don't think it's a grounds problem.. but I will double check.

I only have ONE rotor total.

It's been used in every test. The backup rotor I had turned out to be broken, physically cracked.

I have thought timing chain too, only because thats what happened on my 258...

We set TDC.. (turned the balancer until the #1 had a compression cycle and then topped out.) and then set the cap to the #1 plugwire.

Whats the firing order on the 305? I know it hasn't changed from what I had before, but I'm really grabbing at straws here.

This one spark thing is really getting me.. One single spark every time I crank it.
Infernozx is offline  
post #6 of (permalink) Old 09-07-2005, 01:11 PM
john luttrell
Guest
 
Posts: n/a
Re: Continuation of the \"I hate GM\" thread.

At this point I would suggest changing the module again. I have in the past bought new electronic parts for auto's as well as aircraft only to find the new part is bad.

I reposted below with trouble shooting info; this info has helped me through the years.
post #7 of (permalink) Old 09-07-2005, 03:49 PM
john luttrell
Guest
 
Posts: n/a
Re: Continuation of the \"I hate GM\" thread.

HEI Trouble Shooting; hope this helps


Coil:
Clean it up and look at the clear epoxy for signs of arcing to ground.


A - coil secondary output terminal(where
the carbon brush spring makes contact)
B - RED wire (BATT terminal connects here)
C - BLACK ground (held down by a coil mounting
screw)
D - YELLOW (or WHITE) wire (TACH terminal)



Using this chart, make the following Ohm Meter tests. Any failing test means replacing the coil.
Probe Points Expected Results
B-D about 1.6 ohms
A-C 8.1-8.2 kiloohms
B-C & C-D > 1.2 megaohms, but not infinite
A-B & A-D infinite

Check if the ground strap is in the coil. A broken or loose strap will arc, making a sound like the advance weights clicking against the side of the cap. Some new kits don't come with this strap and many forget to put it on.

GM HEI (internal coil) 1974-1975 6k-30k ohms secondary GM HEI (internal coil) 1976-1979 Infinity GM HEI (internal coil) 1980- (see text)

The resistance between the primary terminals of the coil should be no more than 1.0 ohms. The resistance between the secondary output terminal and the primary should be between 6k and 30k ohms. Integral coils on applications later than 1975 should have infinte ohms between the secondary and the primary. However, 1980 and later applications should be replaced if there is infinte ohms between both the primary and tach lead. This is also true of applications later than 1980 with an externally mounted coil.

Q: My question is why measure for DC resistance between one lead of the secondary and a lead of the primary anyway? Shouldnt this always be infinte?

It would for what you might think of as a regular transformer but the coil is an "autotransformer" -- no pun intended. It's like a transformer with a centertap and no secondary. The "primary" would be from the centertap to one side. The "secondary" across both sides like so:



So the primary and the seconday windings aren't electrically isolated from each other.

Module:



Modules I've seen have the terminals labeled. This may help if yours isn't. The (G) is the ground terminal, and it is one of the holes that the screw runs through to attach the module to the distributor.

1. Remove the module from the distributor. (watch out for that nasty dielectric grease on the underside, It's relatively hamless, but goopy) Connect a test lamp between the B and C module terminals and jumper +12 volts to the B terminal and then ground the module at the (G) terminal. If the lamp lights then the module is bad.
2. If the module passes step one, then jumper between the B and G terminals. The lamp will light if the module is ok.

If you suspect the module at this point, you might as well take it with you to the parts store if they'll test it for you, and confirm your diagnosis before you buy a new one.

Pickup Coil:

1. Remove the pickup coil leads (carefully) from the module. Connect the ohmmeter to the base of the distributor and the pickup coil lead. The book doesn't specify which one, so I assume either one will do. Personally, I checked both. Operate the vacuum advance through it's full range. (I didn't have my vacuum pump with me so I sucked on the vacuum line going to the advance. If you use that method you're likely to spend the rest of the day spitting. I don't reccomend it, but it'll do in a pinch.) The meter should read infinite in all positions.
2. Connect the ohmmeter between the leads coming from the pickup coil and operate the vacuum advance through it's full range with a vacuum pump. The meter should read 650 to 850 ohms in all advance positions.
post #8 of (permalink) Old 09-07-2005, 03:54 PM
 
Join Date: Sep 1999
Posts: 5,383
Thanks: 0
Thanked 1 Time in 1 Post
 
Re: Continuation of the \"I hate GM\" thread.


I hope this is what you are after...
http://www.junkyardgenius.com/ignition/dist01.html

It's my web site, but it has a mind of it's own!
Junk Yard Genius is offline  
post #9 of (permalink) Old 09-07-2005, 06:48 PM Thread Starter
 
Join Date: May 2001
Posts: 3,501
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Continuation of the \"I hate GM\" thread.

Thanks for the documentation John and TR.. I'll get on that next time I go out to vist the Jeep.

I was just thinking today, considering the Distributor is self contained.. eg. it just takes one power input of 12V.. I could theoretically bench test it out of the jeep right?

Load it up in a vice, and spin the cam gear while testing for spark.. It also makes it a little easier to mix and match parts, as I don't have to reach into the engine bay under the firewall/cowl.

Can I bench test the distributor? or is that going to mess something up?
Infernozx is offline  
post #10 of (permalink) Old 09-08-2005, 04:30 AM
Addict
 
jeepnut_nh's Avatar
 
Join Date: Mar 2002
Location: near Nashua, NH
Posts: 484
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Continuation of the \"I hate GM\" thread.

[ QUOTE ]
Whats the firing order on the 305? I know it hasn't changed from what I had before, but I'm really grabbing at straws here.

This one spark thing is really getting me.. One single spark every time I crank it.

[/ QUOTE ]

your firing order will be on the intake near the carb(throttlebody)...probably raised numbers but may be stamped.....is the distributor rotating the right direction?

also try setting at TDC and try again, if same, pull out and try moving ONE tooth to either direction and see what happens, my understanding is that many motors will run ALL F-ED up with distributor even just one tooth off

good luck and dont think poorly of GM because one used motor may be a bit off, i had years of very dependable service out of every GM ive owned

luck to ya
jeepnut_nh is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome