• Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech

65 fires for first time but weak spark

  • Thread starter Thread starter dachillman65
  • Start date Start date Jan 11, 2006
D

dachillman65

New Member
Apr 5, 2005
17
0
0
Jan 11, 2006
#1
  • Jan 11, 2006
  • #1
ive got a problem. i installed my 302 small block into my 65 coupe. i went through all the wiring and thought it would all work, but when i went to start it, it turned right over and was tryin to start it, but the spark was so weak we had to connect the batter to the coil to get a good spark. the battery voltage is just over 12 volts but dropped to 10.3 volts when we cranked it. with the car hotwired, it started without even hitting the throttle. ive checked all the connection to the soleniod, battery, coil etc in the engine compartment. anyone got any suggestions as to where my problem is coming from? ohh and the coil is only about 6 months old. any help would be great. ill post some pics soon for you all too.
 

xoxbxfx

Founding Member
May 9, 2001
3,959
0
0
Southlake, TX
Jan 11, 2006
#2
  • Jan 11, 2006
  • #2
my guess is just old wiring... old wiring starts to deteriorate and you start dropping voltage along the way
 

HistoricMustang

Active Member
Apr 11, 2003
2,359
0
46
Confederate States of America
Jan 12, 2006
#3
  • Jan 12, 2006
  • #3
dachillman65 said:
ive got a problem. i installed my 302 small block into my 65 coupe. i went through all the wiring and thought it would all work, but when i went to start it, it turned right over and was tryin to start it, but the spark was so weak we had to connect the batter to the coil to get a good spark. the battery voltage is just over 12 volts but dropped to 10.3 volts when we cranked it. with the car hotwired, it started without even hitting the throttle. ive checked all the connection to the soleniod, battery, coil etc in the engine compartment. anyone got any suggestions as to where my problem is coming from? ohh and the coil is only about 6 months old. any help would be great. ill post some pics soon for you all too.
Click to expand...

Is the engine grounded well...................I use two on mine. Off the intake and off the front of the block to the frame rail.

You can test your grounding by using a set of jumper cables. Simply take either the "red" end or the "black" end and clamp metal on the engine and then clamp metal on the frame. Most will be amazed at how much better the engine runs!! Try it!

HistoricMustang
www.historicmustang.com
 
You must log in or register to reply here.

Similar threads

T
2001 GT 4.6 V8 weak crank no start.
  • The-Bamboo-Farmer
  • Nov 12, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
2
Views
178
1996 - 2004 SN95 Mustang -General/Talk- Nov 13, 2025
The-Bamboo-Farmer
T
K
Engine 2000 Mustang GT - Fuel issue post-blown spark plug repair
  • kenster1092
  • Feb 26, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
328
SN95 4.6L Mustang Tech Mar 10, 2026
kenster1092
K
F
1986 mustang no start
  • foxyjamss221
  • Oct 11, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
4
Views
307
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Oct 13, 2025
foxyjamss221
F
F
Spark Plugs Caused Rough Idle & Driving
  • firevert
  • Sep 1, 2025
  • 2005 - 2009 Specific Tech
Replies
3
Views
387
2005 - 2009 Specific Tech Sep 3, 2025
Noobz347
L
Engine Why won't the motor start if I have spark and fuel
  • LeviAnderson
  • Nov 20, 2025
  • Fox 5.0 Mustang Tech
Replies
3
Views
405
Fox 5.0 Mustang Tech Nov 20, 2025
AeroCoupe
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?