voltage drop - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Electrical
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 03-24-2007, 11:25 AM
Registered User
 
Last photo:
Join Date: Feb 2006
Location: Tennesse
Posts: 46
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
voltage drop

Hi folks,
I am working through electrical problems on my engine test stand. A jpeg attachment of the schematic I used for the engine stand from hotrodders.com is included.
The only changes to the schematic was dropping the ballast resistor (HEI ignition) and addding a relay switch for the electric fan. I have checked, rechecked, and even had my wife go behind me and verify that it is as the schematic says with the exception of the above mentioned changes.

-The battery ground is to the block with a good connnection.
Should I have it grounded somewhere else?
-Alternator is ground from one of the small extending bolts to a ground on the block.
Is this correct?

Now, my problem: I keep blowing the 30 amp fuse from the "BAT" lug on the ignition switch to the starter "BAT" lug. As soon as I turn on the ignition switch it blows...Fuses are not that expensive, but I will soon have to stop and sweep the floor!

What is causing me to blow the fuse(s)(s)(s)(s)(s)(s)(s)(s)(s)(s)?!!!!

Any help you can provide would be most appreciated!

Jason
DE OPRESSO LIBER!
Attached Thumbnails
Click image for larger version

Name:	electrical.jpg
Views:	81
Size:	68.2 KB
ID:	19762  

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 03-24-2007, 11:57 AM
Registered User
 
Last photo:
Join Date: Mar 2007
Location: LAKE CITY, FLORIDA
Age: 64
Posts: 50
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
When you turn the key on you are sending power to the fan, fuel pump, and distributor. Since the fan and pump are fused circuits, I would guess something isn't right with the distributor wiring. Remove all the wires from the ign. terminal at the switch and try again. This will verify the ign switch is ok.(if the fuse doesn't blow) Then reattach each wire one at a time and test again to determine which circuit is grounding.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 03-24-2007, 01:35 PM
Registered User
 
Last photo:
Join Date: Feb 2006
Location: Tennesse
Posts: 46
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Just returned from the parts store...We tested the Petronix Flame Thrower distributor module and found that it was bad...That module was new. Comparing my Petronix coil to several new stock GM coils, it read the same. So, I got a new one with an extra one to boot. Would a bad module cause the blown fuses?...

I will take the sytem down to bare minimum and replace the wires one at a time, see how that goes...

Thanks,

Jason
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 03-24-2007, 03:02 PM
Registered User
 
Last photo:
Join Date: Mar 2007
Location: LAKE CITY, FLORIDA
Age: 64
Posts: 50
Wiki Edits: 0

Thanks: 0
Thanked 2 Times in 2 Posts
After taking a closer look at your diagram, I have a feeling the distributor wiring is incorrect. I don't understand how you can have two circuits for "crank and run". I'm not familiar with the setup you are using. Evidently you are supposed to have 12V for cranking and that should be wired to the start terminal on the ignition switch. After the engine starts, the power should go thru the ballast resistor which reduces the voltage, and that should be wired to the ignition terminal on the switch. Take a look at the diagram supplied by the manufacturer, you may be damaging the module.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 03-24-2007, 03:18 PM
T-bucket23's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Engine basic condition - how to check Last photo:
Join Date: Aug 2005
Location: Massachusetts
Age: 57
Posts: 5,362
Wiki Edits: 26

Thanks: 9
Thanked 145 Times in 128 Posts
Your diagram seems to be missing a ground from the dist, are you sure that black wire isnt supposed to be a ground.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 03-24-2007, 04:34 PM
steve392's Avatar
just passin' thru
 
Last wiki edit: How to title a hot rod
Last journal entry: Willys - Body and Paint
Last photo:
Join Date: Feb 2005
Location: NJ
Posts: 273
Wiki Edits: 2

Thanks: 0
Thanked 7 Times in 7 Posts
jmbjs,

That diagram is from my setup. I drew it, and I see you mentioned that you got it off this board...No problems with you using it, but did you see the comments to this diagram by Docvette? I'm think you did, because I believe he was the one that mentioned the relay for the fan. (I did not go back and check the post, but that is what I recall.)

I have a Vertex electronic distributor that needs to be hooked up as shown. I got that part of the diagram directly from the Vertex instructions. This diagram for your setup may not be correct...

The distributor is grounded through the distributor body to the engine block. This setup works fine for me, with no blown fuses, but if you have a different type distributor, you may have something mis-wired. Please follow the wiring instructions that came with your distributor or module.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 03-24-2007, 05:39 PM
docvette's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Rebuild an alternator Last photo:
Join Date: Mar 2004
Location: Lafayette, california
Age: 62
Posts: 7,362
Wiki Edits: 12

Thanks: 0
Thanked 6 Times in 3 Posts
Quote:
Originally Posted by jmbjs
Just returned from the parts store...We tested the Petronix Flame Thrower distributor module and found that it was bad...That module was new. Comparing my Petronix coil to several new stock GM coils, it read the same. So, I got a new one with an extra one to boot. Would a bad module cause the blown fuses?...

I will take the sytem down to bare minimum and replace the wires one at a time, see how that goes...

Thanks,

Jason
Doc here,

IF this is a Stock type GM in Cap Coil type, and is connected as per your drawing, REMOVE the Black wire from the power (IGN) and replace the fuse..

Turn it back on and see if the fuse does not blow..IF not, you had the Ground of the Dizzy on the IGN line..And yes, that will trash a module.

If you have something DIFFERENT , refer to your installation diagram as per the Black wire..

Doc
__________________
Aftermarket Solutions
Electronic & Electrical
Innovations
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 03-24-2007, 05:48 PM
vicrod's Avatar
life is a ride
 

Last journal entry: 2014
Last photo:
Join Date: Nov 2005
Location: Telford, PA
Age: 72
Posts: 1,361
Wiki Edits: 0

Thanks: 0
Thanked 63 Times in 59 Posts
The GM HEI distributor needs 12 volts to start and run. That's it.
The ignition switch (ign.) terminal post must be hot when in the start position.
If not a wire is needed from the I terminal post on the starter to the distributor.

vicrod
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 03-24-2007, 09:49 PM
Registered User
 
Last photo:
Join Date: Feb 2006
Location: Tennesse
Posts: 46
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Steve392,
I appreciated you posting that schematic on the website. Although it was slightly different from my needs, it has greatly helped me to understand the basic wiring required to power an engine. My wife and I, through this website figured out what we needed. I read closely the recommendations that DocVette made when he suggested using the relay. I made the few suggested changes to the wiring, installed a new module, and she fired right up! Now I just have to dial her in.
Once again, I really do appreciate the knowledge that you guys/gals provide. This engine stand is a project I took on out of the frustration of cramming a newly built engine into a vega and it failing (although I'm not sure why the engine failed. Anybody interested in trying to help me figure out why?). I vowed that I would never do that again without getting the engine right. I figured that I needed to go back to the basics of an engine, with no distractions of shifters, transmissions, rollbars, etc...I tried to go to far, too fast, so that's why I built the stand, back to the basics, and I have learned a tremendous amount. All of my information comes from this website, a bunch of books, and occasionally, other websites. As long as you guys keep giving the quality advice, I will continue to read, and occassionally ask questions. My son and I were very proud today when that engine came to life.

Take care,

Jason

*My favorite saying: Experience can be expensive!
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 03-24-2007, 10:02 PM
docvette's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Rebuild an alternator Last photo:
Join Date: Mar 2004
Location: Lafayette, california
Age: 62
Posts: 7,362
Wiki Edits: 12

Thanks: 0
Thanked 6 Times in 3 Posts
Doc here,

KEWL!!

Glad to hear it' Roared to life!

GOOD JOB!

Keep us updated on progress..

Doc
__________________
Aftermarket Solutions
Electronic & Electrical
Innovations
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 03-25-2007, 04:48 PM
steve392's Avatar
just passin' thru
 
Last wiki edit: How to title a hot rod
Last journal entry: Willys - Body and Paint
Last photo:
Join Date: Feb 2005
Location: NJ
Posts: 273
Wiki Edits: 2

Thanks: 0
Thanked 7 Times in 7 Posts
Jason,

Glad to hear it worked out for you.

Steve
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 03-25-2007, 06:40 PM
Registered User
 
Last photo:
Join Date: Feb 2006
Location: Tennesse
Posts: 46
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Hey folks,
just wanted to update you on the engine test stand and sbc 350 engine...attached are some pics of the finished stand. I simply took a engine stand with cast wheels, re-enforced it, extended the front to accomodate the radiator, fuel tank, dash and battery shelf. I used the shematics that Steve392 posted (with some adjustments and a new control module) and the engine fired right up. I soon found out she was running real hot. I shut her down to see what I could do. She sputtered, kicked and coughed after I shut the key off, but finally gave up...
I discovered the fan was not blowing in the right direction, changed the polarity and squared that away....
I have learned to be patient and not keep cranking on it hoping the late night fairies have fixed the problem, so back to the books...
Oil pressure is 50-55, firing is good, but when I looked at the carb getting it up to 2200+ for the 20 minute break-in, the carb seems to be dumping a LOT of gas down her throat...The fuel pressure was between 5-6...
I have NOT set any timing other than the intitial timing. The rest of the procedures for timing have been a grey area to me. So, for the next 2 weeks I will be cracking the books, reading this forum and learning about setting the rest of the timing...the engine will not crank till I learn and understand the fundamentals. You guys have been more of a help than you will realize. I'm sure there are also others out there that read a heck of a lot more than they post, and I'll bet they appreciate the expertise as much as I do.

Take care,
Jason
De Oppresso Liber!
Attached Thumbnails
Click image for larger version

Name:	Engine-stand-1.jpg
Views:	79
Size:	31.4 KB
ID:	19825   Click image for larger version

Name:	Engine-stand-2.jpg
Views:	73
Size:	15.2 KB
ID:	19826   Click image for larger version

Name:	Engine-stand-3.jpg
Views:	65
Size:	11.1 KB
ID:	19827  
Reply With Quote Quick reply to this message

Recent Electrical posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last 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:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may 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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Just a Dead Battery? 1quiknova Electrical 7 06-07-2006 08:04 PM
System-wide Voltage Drop 66Parisienne Electrical 4 08-03-2004 08:20 PM
Voltage Drop sixty5 Electrical 5 07-24-2003 12:02 AM
voltage drop bad502 Electrical 5 07-19-2003 11:14 AM
Voltage Drop Nick Davis Electrical 6 06-16-2003 03:48 PM


All times are GMT -6. The time now is 04:19 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.