Motor will only run when the coil is jumped.

[mudchariot]

Motor will turn over fine, but will not run. I've gone through all the electrical system that I can think of and picked everyone's brain. No answers. I can run a jumper to the coil wire (purple) and the motor will start and run just fine. I've replaced the starter, alternator, cap, rotor, wires, plugs, all known fuses good, ignition resistor tested good, battery is charged... I'm out of ideas. Please help!

 

[GA_Boater]

What V-P are you working on? We don't know.

Have you tried tracing the purple wire back to it's source since that's where the ignition voltage to the coil comes from. From the sounds of it, you're throwing money and parts at instead of seriously troubleshooting.

 

[mudchariot]

I traced the purple wire back to the alternator that's why I replaced it. It has circuitry on it and I thought maybe it went bad or got shorted. I don't know how the purple wire gets fed juice from there at all..... I don't know the circuitry...

 

[mudchariot]

BTW, I'm working on a 2001 Volvo Penta 4.3 V6.

 

[dypcdiver]

Check the alternator is working, it supplies the power when the key moves from the start position.

 

[mudchariot]

dypcdiver, I replaced the alternator bc I was figuring that's what the issue was. Not it. That's why I'm so baffled!

 

[jimmbo]

Check the alternator is working, it supplies the power when the key moves from the start position.

Perhaps the ignition switch has failed

 

[mudchariot]

Put a new ignition switch on it, does the same thing...

 

[dypcdiver]

"It has circuitry on it and I thought maybe it went bad or got shorted."
That circuitry should be the diode. I still think next time you get the motor running with the coil jumpered, you need to check that the alternator is producing power, ie at least 13.6 volts.
During the cranking to start the power to the coil is supplied from the cranking circuit. The engine should fire. if it does not then you need to check that power is getting to the coil at that point.
If we knew what motor we are talking about perhaps a circuit diagram could be consulted.
The same circuit involves the fuel pump relay.

 

[mudchariot]

4.3GL motor. The alternator(new) has the correct voltage while the engine is jumped at the coil and running. I put a new starter on because the old one was sticking, so that should eliminate that. The switch was replaced and the safety lanyard was bypassed to eliminate those as culprits. Are there any other safety switches in the circuit that would keep the engine from running? I don't have a wiring diagram so I can't look that up. Does anyone have one that they would share?

 

[bruceb58]

The alternator has nothing to do with the ignition circuit. The diode from the alternator only energizes the fuel pump relay.

The next step to check is corrosion at the wiring harness connector.

 

[mudchariot]

I will try and check that tonight. Does anyone have a wiring diagram for this motor? That would help a TON!!!

 

[Scott Danforth]

its in the manual.

however, if you understand motors, you can understand the standard wiring colors

Black	Ground	Negative / Neutral Main Return
Blue-Stripe	Tilt up and or trim out	Tilt and or trim circuits
Brown	Alternator Charge Light	Generator Terminal or Alternator Auxiliary Terminal to Regulator
Generator Armature	Generator Armature to Regulator
Pumps	Circuit Breaker or Switch to Pumps
Brown w/Yellow	Bilge Blowers	Circuit Breaker or Switch to Blower
Dark Blue	Cabin & Instrument	Circuit Breaker or Switch to Lights
Green or Green w/Yellow Stripe	Bonding System	Grounding Wires (if insulated)
Green Stripe	Tilt down and/or trim in	Tilt and or trim circuits
Grey	Navigation Lights	Circuit Breaker or Switch to Lights
Tachometer	Tachometer Sender to Gauge
Lt. Blue	Oil Pressure	Oil Pressure Sender to Gauge
Orange	Accessory Feed	Ammeter to Alternator or Generator
Common Feed	Distribution Panel to Accessory Switch
Feed	Accessory Circuit Breakers or Switches
Pink	Fuel Gauge	Fuel Gauge Sender to Gauge
Purple	Ignition	Ignition Switch to Coil & Electrical Instrument
Instrument Feed	Distribution Panel Electrical Instruments
Red	Instrument Feed	Distribution Panel to Electrical Instruments
Power Feeds	Positive Main Power (particularly un-fused)
Tan	Water temperature	Water temperature sender to gauge
Yellow	Generator Field	Generator to Regulator Field Terminal
Ground	Negative / Neutral Main Return
Yellow w/Red	Starting Circuit	Starting Switch to Solenoid

COLOR ITEM USE

 

[mikemj]

have you tried the ignition control module and where are you jumpimg it from and to on the coil