No Spark on one cyl

[Sugar Sand 120]

Hi, first time on iboats. Looking for some help!

I do not have a (DVA) Tester....not sure what it is?

I have a 120 hp Sport Jet boat. I believe it is a force motor. I started with a new switch box. I now can start the motor and runs on three of the four cylindars. I have strong spark with approx 1/2" spark gap on the top three cylindars when cranking the motor to a ground. The lower cyl is dead. I pulled the complete electronic board off again amd swapped the lower coil with the top good one. The bottom cyl still dead. Top one is good yet. I checked the resistance of each plug wire, they are all good. I swapped plugs and they are all good. So far all plug wires, plugs and coils are good. I also checked resistance of each coil neg of each coil to the each coil tower and that runs 950ohms. S/B 800-110. I tried to get a voltage reading on each coil neg/pos with a VOM. This is to be 150-250 volts on a DVA 400 setting. I am having problems getting voltage reads with a plan VOM.

Trigger: resistance check is good s/b 700-1000 Ohms it is 890.

Switch Box: The switch box has three wire groups. Left side feeds the (4) coils (four different green combinations and ther own grounds). The top left has (2) blues used and two reds caped and not used, stop lead blk/yellow goes to switch. Bottom left has a violet, white, white/black and brown goes to the trigger.

Stator (purpose for charging): I did a resistance test on the stator Green/white to White green, s/b 500/600 Rx10 ohms. I have 713 ohms. This sounds bad but I do not understand if the stator feeds the switch box and all coils how would one coil be dead and three good? I also tested the Stator White/green to ground and Green/White to ground which shows no continuity on both which is good.

Not sure where to go from here. How often does a new switch boxes come bad out of the box? (One question I have is the new switch box has two red wires that are not used(capped), same as the OEM I replaced)?? Makes me think one red is needed for the bottom cylinder for some reason??

Help!
John

 

[jerryjerry05]

Re: No Spark on one cyl

The first thing to do on any outboard is do a compression check.Do that and get back.Jerry

 

[Sugar Sand 120]

Re: No Spark on one cyl

Thank you for the reply Jerry. I have one problem, my boat is at the cabin and wished to find a solution before I went back in two weeks. I agree with testing compression first but didn't see how this would affect ignition issues. I will test each cylinder and let you know. I do wish to find a solution for the lack of voltage to the one cylinder. I have followed my books instructions and it stated to proceed with sequential step by step tests and cylinder compression was not part of the ignition series of tests. One question I have is that the Stator has two capacitor charging coils. The coils produce AC voltage then conducted to the switch box where it is stored in a capacitor. This is happening but the switch box is not sending it to the 4th coil? The trigger also produces AC voltage and sends it to a (SCR) switch in the switch box, is this my issue. The resistance check I did on the trigger was good 890 ohms two tests, s/b 700-1100 ohms.

My stator has(4) wires, two yellow wires to the auto enricher and voltage regulator. A white/green and green/white wires go to the switch box. The green /white provides voltage to #3 & #4 coils. The White /green provides voltage to #1 & #2 coils. I should have two dead coils if the stator was defective? The resistance check between the greens s/b 500-600 +/- 10% OHMS and, I have 713 ohms. 660 OHMs would be upper limit. Looks to be a bad stator but doesn't make sense.

appreciate any help
John

 

[paul88]

Re: No Spark on one cyl

Well, these systems are fairly complex. You should have a shop manual for this to do proper diag, and sometimes some expensive tools. I think you have a manual for all of these readings.

First, do you have no spark or can you get a weak spark? 1/2" is a lot of gap, try something smaller and see if you get anything. Weak ignition points to the coil or CD box, depending on your ignition type. No spark points to the trigger, CD, or coil. Considering that the stator is common to all plugs, you can rule that one out with some degree of certainty, though it may not be in the best condition.

Second, you should start simple. Are there any shorts in your wires? Plugs have good connection? Socket corroded? Grease in the quick connects? These parts are expensive, you shouldn't replace anything until you are positive it is the problem.

Third, make sure all components are disconnected when you are making your measurements and that you are on a good contact point. Some grime can make a big diffrence in your resistance readings, and some other component can make a connection to ground and act as a parallel resistor.

Also, a good troubleshooting technique is to swap similar components in the system and observe the results. You said you swapped the coils and the bottom one still didn't fire, so you can rule the coils out. Try swapping the CD boxes and see what happens. Make sure your battery is charged as well. The stator doesn't put out very much of anything until 750RPM on my motor anyway. 17A at 4000RPM

I don't know what you mean by AC voltage (alternating current voltage?). Sinusoidal AC will not charge a cap, the cap will always fight the change in voltage. If it is a partial sine then you can get some charge.

P.S. Compression is not relevant to ignition, though it is a good test to perform ;-)

 

[Sugar Sand 120]

Re: No Spark on one cyl

Well, these systems are fairly complex. You should have a shop manual for this to do proper diag, and sometimes some expensive tools. I think you have a manual for all of these readings.

First, do you have no spark or can you get a weak spark? 1/2" is a lot of gap, try something smaller and see if you get anything. Weak ignition points to the coil or CD box, depending on your ignition type. No spark points to the trigger, CD, or coil. Considering that the stator is common to all plugs, you can rule that one out with some degree of certainty, though it may not be in the best condition.

Second, you should start simple. Are there any shorts in your wires? Plugs have good connection? Socket corroded? Grease in the quick connects? These parts are expensive, you shouldn't replace anything until you are positive it is the problem.



Third, make sure all components are disconnected when you are making your measurements and that you are on a good contact point. Some grime can make a big diffrence in your resistance readings, and some other component can make a connection to ground and act as a parallel resistor.

Also, a good troubleshooting technique is to swap similar components in the system and observe the results. You said you swapped the coils and the bottom one still didn't fire, so you can rule the coils out. Try swapping the CD boxes and see what happens. Make sure your battery is charged as well. The stator doesn't put out very much of anything until 750RPM on my motor anyway. 17A at 4000RPM

I don't know what you mean by AC voltage (alternating current voltage?). Sinusoidal AC will not charge a cap, the cap will always fight the change in voltage. If it is a partial sine then you can get some charge.

P.S. Compression is not relevant to ignition, though it is a good test to perform ;-)

To my surprise the Stator produces Alternating current sends this to the switch box And also sends this to the volatge regulator and converts the AC to direct current to charge the battery. I do not have any spark to the one cylinder. The other three cylinders are blue, snappy and hot. The Trigger also sends AC current to the switch box to a SCR switch (Silicon Controlled Rectifier). This switch is a on/off switch does not direct where the spark goes. The switch box does this. The stator sends AC current to the switch box but is held in a capacitor. I think I have purchased a defective switch box from Sieler Marine two weeks ago.

Agree?

John