how to test trigger

[Nickmell]

Is there any way to test the trigger on a 79 chrysler 115? Im chasing a spark issue and hopeing the trigger is the problem. I have 11 volts going into the blue wire on the trigger (drops to 9 when cranking) but only 7 coming out on the white wire
(6 while cranking). Could this be a sign of a bad trigger? it has this style trigger

 

[Frank Acampora]

Re: how to test trigger

Unfortunately, according to the manual, there is no way to test an electric eye other than replacing with a known good one. There are two styles: red and black. They work differently but will work on the same Motorola CD boxes.

If it helps, The blue wire energizes a small bulb inside the unit. When the plastic shutter on the rotor is on an open space, light falls on a photocell which generates a voltage sent to the CD box, When the light is blanked off, the voltage stops and the transistor inside the CD box switches, dumping the capacitors into the coil. 7 volts coming out could be correct: I have never measured output voltage.

 

[Nickmell]

Re: how to test trigger

Unfortunately, according to the manual, there is no way to test an electric eye other than replacing with a known good one. There are two styles: red and black. They work differently but will work on the same Motorola CD boxes.

If it helps, The blue wire energizes a small bulb inside the unit. When the plastic shutter on the rotor is on an open space, light falls on a photocell which generates a voltage sent to the CD box, When the light is blanked off, the voltage stops and the transistor inside the CD box switches, dumping the capacitors into the coil. 7 volts coming out could be correct: I have never measured output voltage.

Ok that helps my understand how the system works. Sound like this could be my problem then since I and just getting a spark one in a while mostly when letting off the key and the cdi seems to be giving the coil power since it have lit me up several times. I have also switch coils to one from a yamaha atv and It still did the same thing so I think I will give the trigger a try. Thank you.

 

[Frank Acampora]

Re: how to test trigger

If I understand correctly, you do get spark when letting off the key but not while cranking. If this is the case, look at the switch. You may have a corroded or broken ignition switch.

Simple to test: In start position there should be 0 zero ohms between the "B" terminal and the "S" terminal. Alternatively, you should be able to measure 12 volts if the wiring is connected. Similarly, the "B" terminal and the "I" or "A" terminal should show zero ohms or 12 volts with the wires connected and the switch in the run position.

ANY resistance or drop in voltage means a corroded or bad switch. At about 20 bucks, a switch is easy and cheap to replace. Use a standard 6 pole , push-to-choke switch.

If you open a bad switch, inside you will see a fiber disc with segments of copper plated on it. The copper is thin and easily damaged or corroded beyond use. I am surprised that these switches last more than a year in use.

 

[Nickmell]

Re: how to test trigger

If I understand correctly, you do get spark when letting off the key but not while cranking. If this is the case, look at the switch. You may have a corroded or broken ignition switch.

Simple to test: In start position there should be 0 zero ohms between the "B" terminal and the "S" terminal. Alternatively, you should be able to measure 12 volts if the wiring is connected. Similarly, the "B" terminal and the "I" or "A" terminal should show zero ohms or 12 volts with the wires connected and the switch in the run position.

ANY resistance or drop in voltage means a corroded or bad switch. At about 20 bucks, a switch is easy and cheap to replace. Use a standard 6 pole , push-to-choke switch.

I tried replacing the switch but the one that I bought only had 4 connectors where the one on it now had 5 so im not 100% it was hooked up correctly but it still did the same thing. Ill trytesting it and see what it reads.

 

[Nickmell]

Re: how to test trigger

If I understand correctly, you do get spark when letting off the key but not while cranking. If this is the case, look at the switch. You may have a corroded or broken ignition switch.

Simple to test: In start position there should be 0 zero ohms between the "B" terminal and the "S" terminal. Alternatively, you should be able to measure 12 volts if the wiring is connected. Similarly, the "B" terminal and the "I" or "A" terminal should show zero ohms or 12 volts with the wires connected and the switch in the run position.

ANY resistance or drop in voltage means a corroded or bad switch. At about 20 bucks, a switch is easy and cheap to replace. Use a standard 6 pole , push-to-choke switch.

If you open a bad switch, inside you will see a fiber disc with segments of copper plated on it. The copper is thin and easily damaged or corroded beyond use. I am surprised that these switches last more than a year in use.

Well did this test and everything seems to be normal with my key switch. Not sure which direction to go now.

 

[Nickmell]

Re: how to test trigger

ok so I did the trouble shooting off outboard ignitons.com
Clean all battery connections and engine grounds.
Make sure the CD module is grounded. Units using rubber shock mounts require a ground wire fastened from the pack to the engine block.
Connect a spark gap tester to the high tension lead coming from the ignition coil and set it to approximately 1/2”. If it fires when you crank the engine over, there is a problem in the distributor cap, rotor button or spark plug wires.
Check voltage present on the blue wire at cranking. It MUST be at least 9? volts. if not, the problem is likely in the harness, key switch, starter or battery.
Connect a DC voltmeter to the white/black wire (while it is connected to the distributor) and rotate the engine. There should be some fluctuation in the meter reading. If the reading is high, and fails to move up and down, there is definitely a problem inside the distributor. If the reading is low, disconnect the white/black wire rom the distributor and with the key switch turned on, strike the white/black wire against engine ground. The unit should fire each time. If it does, then the CD module is usually good and the points (or Preamp) require checking. If the CD module fails to fire with this test, then the CD module is usually bad.
Check DVA voltage on the gray wire going to the coil, it should be approximately 200 volts at cranking. If the voltage is right, replace the coil with another coil and retest or use a load resister if another coil is not available. A coil that is shorted internally will give a low reading. In this case replace the coil and retry.

After repairing the engine, check the battery voltage at approximately 3500 RPM, The MAXIMUM allowable voltage reading is 16 volts and the minimum is 12V. Running below l2V or over 16 volts will damage the ignition. Check for loose connections or a bad battery.


Blue wire seemed to have enough volts and the needle moves on the white/black wire but not sure how many volts its suppose to have or move . It will not arc when I touch it back to the distributor either but I do hear a click inside the distributor each time I touch the wire to it. And I dont have any power on the grey coil wire. Any suggestions?

 

[Frank Acampora]

Re: how to test trigger



Sounds like a bad CD box if there is no voltage on the grey wire. See: When the distributor signals the transistor inside the CD box via the electric eye, that transistor dumps the capacitors into the coil for a very fast voltage rise and a very high, sharp spike of voltage to the sparkplug.

When you crank the engine battery voltage can drop as low as 9 volts and the red wire to the CD box will only charge at 9 volts--should still be enough to spark with a good CD box. But in your case, perhaps not. When you let go of the key, battery voltage rises to 12-13 volts and the capacitors charge fully. Electronics also are getting full voltage and you get a spark---but the engine isn't turning and so it will not start.

With the hood off and the controls in fast idle/warm-up, try rope starting with the ignition on and the choke held closed with some sort of brace. It is not as difficult as you might think--just be certain to brace yourself. You may need a squirt of starting fluid in each carb. (Yeah, I know starting fluid is bad to use but this is a one time use). If the engine starts and runs, then yes, most likely you have a CD box going bad.

Edit: Whoops, clicked on the wrong photo.
BTW: Have you checked the ground from the negative side of the coil to the distributor mount? A broken wire here will give erratic sparks

 

[Nickmell]

Re: how to test trigger

View attachment 206043View attachment 206039View attachment 206040View attachment 206041

Sounds like a bad CD box if there is no voltage on the grey wire. See: When the distributor signals the transistor inside the CD box via the electric eye, that transistor dumps the capacitors into the coil for a very fast voltage rise and a very high, sharp spike of voltage to the sparkplug.

When you crank the engine battery voltage can drop as low as 9 volts and the red wire to the CD box will only charge at 9 volts--should still be enough to spark with a good CD box. But in your case, perhaps not. When you let go of the key, battery voltage rises to 12-13 volts and the capacitors charge fully. Electronics also are getting full voltage and you get a spark---but the engine isn't turning and so it will not start.

With the hood off and the controls in fast idle/warm-up, try rope starting with the ignition on and the choke held closed with some sort of brace. It is not as difficult as you might think--just be certain to brace yourself. You may need a squirt of starting fluid in each carb. (Yeah, I know starting fluid is bad to use but this is a one time use). If the engine starts and runs, then yes, most likely you have a CD box going bad.

Edit: Whoops, clicked on the wrong photo.
BTW: Have you checked the ground from the negative side of the coil to the distributor mount? A broken wire here will give erratic sparks

Damn I was hoping that wasnt the case. I found a trigger for cheap and ordered it so ill give that a try, but will give the rope starting a try. Thank you

 

[Nickmell]

Re: how to test trigger

View attachment 206043View attachment 206039View attachment 206040View attachment 206041

Sounds like a bad CD box if there is no voltage on the grey wire. See: When the distributor signals the transistor inside the CD box via the electric eye, that transistor dumps the capacitors into the coil for a very fast voltage rise and a very high, sharp spike of voltage to the sparkplug.

When you crank the engine battery voltage can drop as low as 9 volts and the red wire to the CD box will only charge at 9 volts--should still be enough to spark with a good CD box. But in your case, perhaps not. When you let go of the key, battery voltage rises to 12-13 volts and the capacitors charge fully. Electronics also are getting full voltage and you get a spark---but the engine isn't turning and so it will not start.

With the hood off and the controls in fast idle/warm-up, try rope starting with the ignition on and the choke held closed with some sort of brace. It is not as difficult as you might think--just be certain to brace yourself. You may need a squirt of starting fluid in each carb. (Yeah, I know starting fluid is bad to use but this is a one time use). If the engine starts and runs, then yes, most likely you have a CD box going bad.

Edit: Whoops, clicked on the wrong photo.
BTW: Have you checked the ground from the negative side of the coil to the distributor mount? A broken wire here will give erratic sparks

Well I have replaced the trigger and cdi still same problem. If it set the distributer where it should be shooting spark to the coil it will spark everytime I turn the key from off to on but dont crank it. and Ideas? Im not 100% I have the key hooked up correctly do you happen to have a picture of your wireing on it? Im lost at this point and about ready to give up on boats and stick with motorcycles.

 

[Nickmell]

Re: how to test trigger

I also tried the rope trick but being by my self It was hard to tell if it was sparking I don't believe it was.

 

[Nordin]

Re: how to test trigger

Check the voltage at bluewire on dist. while cranking. If it drops to 9-10V or lower the CD box will not work properly.
Also check the grounding of the CD box and the dist.
Does it spark when you strike the white/black wire against ground?

 

[Nickmell]

Re: how to test trigger

Check the voltage at bluewire on dist. while cranking. If it drops to 9-10V or lower the CD box will not work properly.
Also check the grounding of the CD box and the dist.
Does it spark when you strike the white/black wire against ground?

Ill try that this weekend, im working out of town so only get an hour or so a week to look at it. Will this key switch work? mine is a 6 pin Marpac Marine Push to Choke Ignition Switch Mercury Boat Key Switch 7 1150 New | eBay

 

[Nickmell]

Re: how to test trigger

Check the voltage at bluewire on dist. while cranking. If it drops to 9-10V or lower the CD box will not work properly.
Also check the grounding of the CD box and the dist.
Does it spark when you strike the white/black wire against ground?

Well I only have 8.3 to 8.7v on the blue wire so what would be causing that? The white and black wire will make a plug spark when it take it on and off the post.

 

[Nordin]

Re: how to test trigger

There you have a issue, does the voltage drop from 12V to 8,3-8,7V while cranking or is it always 8,3-8,7V?
If it drop when you crank, check the starter, the startsolenoid and all thick wires in the electricalsystem for bad connections.

You are loosing voltage somewhere in the system and when you crank, the starter "sucks" current and if there is bad connections the voltage starts to drop if enough current can?t be delivered.

 

[Nickmell]

Re: how to test trigger

There you have a issue, does the voltage drop from 12V to 8,3-8,7V while cranking or is it always 8,3-8,7V?
If it drop when you crank, check the starter, the startsolenoid and all thick wires in the electricalsystem for bad connections.

You are loosing voltage somewhere in the system and when you crank, the starter "sucks" current and if there is bad connections the voltage starts to drop if enough current can?t be delivered.

I have 12.6 volts with the key on then it drops while cranking, I did notice that my negative battery cable get hot after cranking for 10 seconds or so, so maybe I should replace it also. Ill go check all the connections and report back. Thank you.

 

[Nickmell]

Re: how to test trigger

I have 12.6 volts with the key on then it drops while cranking, I did notice that my negative battery cable get hot after cranking for 10 seconds or so, so maybe I should replace it also. Ill go check all the connections and report back. Thank you.

Well I cleaned up all the grounds, took the starter off and cleaned where it grounds to the block, and got rid of some splice block that the last owner had on the battery cables and got the voltage to come up to 9.75 to 10 but still no spark. Could this be a regulator problem?

 

[Nordin]

Re: how to test trigger

Well it can be a regulator issue. Try to disconnect the regulator and check for spark.
You can also connect a second powersupply direct at the terminalstrip and check for spark.
This will give you indication if the trigger and CD box is okey.

 

[Nickmell]

Re: how to test trigger

Well it can be a regulator issue. Try to disconnect the regulator and check for spark.
You can also connect a second powersupply direct at the terminalstrip and check for spark.
This will give you indication if the trigger and CD box is okey.

Ok how would I dissconect the regulator? I have a purple, a red, and a black wire on top, and a ground on the side. I just dont want to burn anything up. Im good at fixing mechanical parts but I am lost when it comes to electrical.

 

[Frank Acampora]

Re: how to test trigger

Try running a short jumper wire from the red terminal on the engine block to the blue terminal. This will supply constant power to the distributor electric eye and the CD box electronics. (remember: Red to the CD box already supplies constant power to the capacitors only). If you now can get spark while cranking, replace the switch and/or the cable. If the switch is bad then you are good to go. If the switch is good, then the cable has an intermittent break in it (not likely) Simply run another wire from the ignition switch to the blue terminal on the engine.