Cranking issue

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Oct 31, 2025 | 05:48 PM

BadgerWI

Thread Starter

7th Gear

Joined: Nov 2024

Posts: 7

Likes: 4

Cranking issue

Have a 79 4 speed with a 390 that I put in a few years ago. I have had difficulty starting the truck after I go through the typical pump once to open the choke and give it an additional 4 - 5 pumps on the accelerator before cranking, slightly holding down the pedal as I crank. I've found that if I ever so slightly turn the key from "on" to "crank" just enough to allow the starter to engage, then let off the key quick so that it immediately turns to the on position, it fires up. In the past I had to crank for several seconds, wait and try again, and again, wearing on the starter and battery.

I put a meter on the ignition module and see that it puts out only 6 volts when running. Have not checked with the meter when cranking as I was doing this solo today. Would my ignition module be failing? Can I run a jumper from my battery terminal to the coil to put 12 volts to the coil be a test to determine if the module is no good? Just looking for some feedback.

Oct 31, 2025 | 06:11 PM

JimsRebel

Cargo Master

Joined: Mar 2008

Posts: 2,573

Likes: 207

From: Washington

Quote:

Originally Posted by BadgerWI

Have a 79 4 speed with a 390 that I put in a few years ago. I have had difficulty starting the truck after I go through the typical pump once to open the choke and give it an additional 4 - 5 pumps on the accelerator before cranking, slightly holding down the pedal as I crank. I've found that if I ever so slightly turn the key from "on" to "crank" just enough to allow the starter to engage, then let off the key quick so that it immediately turns to the on position, it fires up. In the past I had to crank for several seconds, wait and try again, and again, wearing on the starter and battery.

I put a meter on the ignition module (module or coil???) and see that it puts out only 6 volts when running. Have not checked with the meter when cranking as I was doing this solo today. Would my ignition module be failing? Can I run a jumper from my battery terminal to the coil to put 12 volts to the coil be a test to determine if the module is no good? Just looking for some feedback.

6 volts at the ignition coil positive while running is normal.
While it tends to start as soon as you remove current flow to the starter ... does sound like a weak battery... As the voltage will jump up as soon as you remove the heavy draw from the starter motor. Or it could be the starter motor is drawing to much current, dragging the voltage down.
I would run a jumper wire to the coil positive, directly from the battery positive, for testing.
The "I" output of the starter solenoid is supposed to provide full power to the coil positive while cranking, this wire bypasses the resistor wire.

Don't rush out and buy a new DS2 ignition module, this seem extremely unlikely... As it runs fine after it starts.

Jim

Last edited by JimsRebel; Oct 31, 2025 at 06:13 PM.

Oct 31, 2025 | 07:25 PM

kenny nunez

Cargo Master

Joined: Oct 2011

Posts: 2,251

Likes: 305

From: Kenner,La.

Hard start

Look at the fender well solenoid, the small terminal marked “I” should provide 12 volts in cranking mode. This circuit provides current to the coil to help starting.