Electronic Ignition Weak Spark

[RTR]

We have a caterpillar forklift with a 4-cylinder overhead valve engine that looks just like a Ford 601 tractor engine, but runs on propane. It has a Prestolite distributor with electronic ignition. Been trying to get it to Run since we bought it, and I have used a spark tester with an adjustable gap. I can get spark to the spark plugs With a 1/16 inch gap the spark is very thin, and sometimes sparks to the edge of my tester electrode. If I move my tester gap to 1/4", I get no spark on any of the Plugs. It has a brand new ignition Cole, MSD half output 45,000 Volt coil. Has resistor type plug wires.

Could the EI module be bad? Why would that spark be so thin and weak? I thought it was supposed to jump a quarter inch gap and be hotter than that. Anything else in distributor like rust cause this? This is my first troubleshooting with electronic ignition.

This post was edited by RTR on 12/19/2023 at 04:56 am.

 

[JMOR]

(quoted from post at 08:54:15 12/19/23) We have a caterpillar forklift with a 4-cylinder overhead valve engine that looks just like a Ford 601 tractor engine, but runs on propane. It has a Prestolite distributor with electronic ignition. Been trying to get it to Run since we bought it, and I have used a spark tester with an adjustable gap. I can get spark to the spark plugs With a 1/16 inch gap the spark is very thin, and sometimes sparks to the edge of my tester electrode. If I move my tester gap to 1/4", I get no spark on any of the Plugs. It has a brand new ignition Cole, MSD half output 45,000 Volt coil. Has resistor type plug wires.

Could the EI module be bad? Why would that spark be so thin and weak? I thought it was supposed to jump a quarter inch gap and be hotter than that. Anything else in distributor like rust cause this? This is my first troubleshooting with electronic ignition.

This post was edited by RTR on 12/19/2023 at 04:56 am.

ot knowing exactly what EI you have makes for a lot of guessing, however, assuming it is not a capacitor discharge type of EI, then a weak spark, with a known good coil, would most likely mean that you are not getting adequate primary current thru the coil. Generally the primary current needs to be approximately 4 amperes. steady state ON current.

 

[rvirgil_KS]

what is the resistance between the two small posts on the coil and does it have an extra resistor between the ignition switch and the module or coil?

 

[RTR]

(quoted from post at 09:45:01 12/19/23) what is the resistance between the two small posts on the coil and does it have an extra resistor between the ignition switch and the module or coil?

I'll have to check. What is good, what is bad?

 

[RTR]

(quoted from post at 08:49:10 12/19/23)

(quoted from post at 08:54:15 12/19/23) We have a caterpillar forklift with a 4-cylinder overhead valve engine that looks just like a Ford 601 tractor engine, but runs on propane. It has a Prestolite distributor with electronic ignition. Been trying to get it to Run since we bought it, and I have used a spark tester with an adjustable gap. I can get spark to the spark plugs With a 1/16 inch gap the spark is very thin, and sometimes sparks to the edge of my tester electrode. If I move my tester gap to 1/4", I get no spark on any of the Plugs. It has a brand new ignition Cole, MSD half output 45,000 Volt coil. Has resistor type plug wires.

Could the EI module be bad? Why would that spark be so thin and weak? I thought it was supposed to jump a quarter inch gap and be hotter than that. Anything else in distributor like rust cause this? This is my first troubleshooting with electronic ignition.

This post was edited by RTR on 12/19/2023 at 04:56 am.

ot knowing exactly what EI you have makes for a lot of guessing, however, assuming it is not a capacitor discharge type of EI, then a weak spark, with a known good coil, would most likely mean that you are not getting adequate primary current thru the coil. Generally the primary current needs to be approximately 4 amperes. steady state ON current.

Would using a jumper hot wire directly from battery to (+) side of coil help rule this out? Or would it potentially damage the EI unit?

 

[JMOR]

(quoted from post at 13:38:33 12/19/23)

(quoted from post at 08:49:10 12/19/23)

(quoted from post at 08:54:15 12/19/23) We have a caterpillar forklift with a 4-cylinder overhead valve engine that looks just like a Ford 601 tractor engine, but runs on propane. It has a Prestolite distributor with electronic ignition. Been trying to get it to Run since we bought it, and I have used a spark tester with an adjustable gap. I can get spark to the spark plugs With a 1/16 inch gap the spark is very thin, and sometimes sparks to the edge of my tester electrode. If I move my tester gap to 1/4", I get no spark on any of the Plugs. It has a brand new ignition Cole, MSD half output 45,000 Volt coil. Has resistor type plug wires.

Could the EI module be bad? Why would that spark be so thin and weak? I thought it was supposed to jump a quarter inch gap and be hotter than that. Anything else in distributor like rust cause this? This is my first troubleshooting with electronic ignition.

This post was edited by RTR on 12/19/2023 at 04:56 am.

ot knowing exactly what EI you have makes for a lot of guessing, however, assuming it is not a capacitor discharge type of EI, then a weak spark, with a known good coil, would most likely mean that you are not getting adequate primary current thru the coil. Generally the primary current needs to be approximately 4 amperes. steady state ON current.

Would using a jumper hot wire directly from battery to (+) side of coil help rule this out? Or would it potentially damage the EI unit?

an't answer unless know what EI is installed, because some units apply voltage to coil and others supply ground to coil.

 

[5570 standard]

make sure the control module has a good ground

 

[RTR]

Would using a jumper hot wire directly from battery to (+) side of coil help rule this out? Or would it potentially damage the EI unit?

an't answer unless know what EI is installed, because some units apply voltage to coil and others supply ground to coil.[/quote]

Ok. Thank you.

 

[RTR]

Getting 12.2 volts at the ignition coil with key on. Changing the dist. cap, rotor, and plug wires to new parts today.

 

[JMOR]

(quoted from post at 17:25:51 12/21/23) Getting 12.2 volts at the ignition coil with key on. Changing the dist. cap, rotor, and plug wires to new parts today.

ook at voltage on each small terminal of coil, relative to ground while cranking. One side should be alternating between 12.2 and zero.

 

[RTR]

(quoted from post at 16:54:12 12/21/23)

(quoted from post at 17:25:51 12/21/23) Getting 12.2 volts at the ignition coil with key on. Changing the dist. cap, rotor, and plug wires to new parts today.

ook at voltage on each small terminal of coil, relative to ground while cranking. One side should be alternating between 12.2 and zero.

Ok. I can do that. I was also told by the Brillman tech to check ohms?? between 2 small posts on coil while cranking.....to check something between those posts WHILE cranking. I can't remember what it was but the value was supposed to be around 4 (I THINK??). I can't remember, and I called them back but he is out sick! Dang it!

 

[wore out]

''I was also told by the Brillman tech to check ohms?? between 2 small posts on coil while cranking''

Simply put, NO, using an Ohmmeter on a powered circuit is a no-no! (For the sake of the meter.)

 

[RTR]

(quoted from post at 11:57:04 12/22/23)
''I was also told by the Brillman tech to check ohms?? between 2 small posts on coil while cranking''

Simply put, NO, using an Ohmmeter on a powered circuit is a no-no! (For the sake of the meter.)

Like I expressed above, I'm not sure if it was Ohms I was supposed to check but I don't think he said Volts. I will call them back and check today providing they are open.

 

[buickanddeere]

(quoted from post at 17:25:51 12/21/23) Getting 12.2 volts at the ignition coil with key on. Changing the dist. cap, rotor, and plug wires to new parts today.

What is the voltage between the two small posts on the coil . It should alternate between a high voltage low voltage .
Now the same voltage test from the coil s small + terminal to chassis .
Now the same voltage test from the coil s small - terminal to chassis .
As previously asked by others . Need to know if there is a ballast , manufacture of the electronic unit . Ohms across the coil s small posts with the wires disconnected . Current through the coil while cranking ? Is there a ballast resistor ?
Is the battery s positive or negative connected to chassis ?
With the meter on voltage , red lead on the coil s positive and black lead on the coil s negative . Does the meter read the voltage with a negative sign in front of the numbers ?
Spiral wound suppression ignition wires are more robust and reliable than graphite ignition wires .

 

[560Dennis]

Does It have copper plug wires

 

[Janicholson]

We have a caterpillar forklift with a 4-cylinder overhead valve engine that looks just like a Ford 601 tractor engine, but runs on propane. It has a Prestolite distributor with electronic ignition. Been trying to get it to Run since we bought it, and I have used a spark tester with an adjustable gap. I can get spark to the spark plugs With a 1/16 inch gap the spark is very thin, and sometimes sparks to the edge of my tester electrode. If I move my tester gap to 1/4", I get no spark on any of the Plugs. It has a brand new ignition Cole, MSD half output 45,000 Volt coil. Has resistor type plug wires.

Could the EI module be bad? Why would that spark be so thin and weak? I thought it was supposed to jump a quarter inch gap and be hotter than that. Anything else in distributor like rust cause this? This is my first troubleshooting with electronic ignition.

This post was edited by RTR on 12/19/2023 at 04:56 am.

A If the amps in the coil supply circuit, with the engine not running and the key on, is at or near 4, that should saturate the coil with magnetic energy. If not, I would check the resistance of the coil. it should be at 3.3 ohms or so. if t is more like 1.2 ohms it is intended to have a resistor in the circuit. If the coil is out of those specs, I would put a different coil on it first a 12v no resistor required coil.. Jim

 

[RTR]

Ok, so apparently that thin spark was normal because we adjusted the fuel mixture on the LP regulator, and she fired right up and runs now. Granted, changing all of the ignition parts including plug wires probably helped and solved a separate lurking issue.