Firing multiple times on one cylinder

[Nordin]

SORRY Bad spelling. I mean whole assembly, not hole.

 

[pnwboat]

I second what Nordin states. I've never seen just the OEM reed petals. They're always a complete assembly and are pretty pricey.

I've tried various aftermarket reeds petals though the years, Boyesen, CCM and a couple of others that I've probably forgotten. They all work well. Some folks say that you have to change them more often because they are not metal, but composite material. I have a set of Boyesen reeds that are 6 years old in my motor now, and they look just fine.

 

[FWDan]

I've ordered CCM reeds and they should be here in a couple of days. In the meantime, I'd like to figure out my multiple firing issue. I posted electrical component test results earlier. Everything looks good for resistance and voltage except the following:

​Stator: Red wire (connected) puts out too high voltage (1000V) when engine is running. Should be 400V max. (unconnected looks normal)

Trigger: All three wires (connected) put out too high voltage (1000V) when running. Should be 4V. (unconnected looks normal)

Switchbox: All three green output wires to coils put out too high voltage (900+V) when connected and running. Should be 400V max. (I did not test unconnected for fear of damage to switchbox) Coil resistances look good.

I'm leaning toward bad switchbox because trigger and stator are okay unconnected. I think the swithbox is triggering all cylinders at once. Maybe a short in the switchbox?

 

[pnwboat]

I would be leaning towards a bad Switch Box too. It appears that there is some high voltage that is back feeding to the trigger circuit/wires.

 

[Nordin]

Insist with pnwboat leaning to the switch box.

What amazes me is that your high readings for the trigger and the stator output.
With that high voltage it would fried the box.

The stator voltage is suppose to charge the output capacitors (I think there are multiples of it, actually one for each cylinder) and they are build to withstand about 450-650 V.

The trigger voltage is suppose to give signal for the SCR gate (SCR is a Silicon - Controlled - Rectifier or called a thyristor) to switch the SCR anode and cathode and that entails the capacitor to dump the charged voltage in to the ignition coil.

The trigger voltage suppose to be about 0,4-4V depending on the construction of the switch box. Type of SCR and voltage splitting for the gate.
.
With those reading you have, it would fried the SCR too.
This leans me to a back feeding of capacitor voltage to the triggers and the stator.
I think there is diods in the construction of the switch box that should block this.
Maybe they are bad and leaking voltage backwards.

In your case maybe the stator and trigger coil windings act as an accumulator and "save" the switch box to fail totaly.

 

[Fun Times]

I am having trouble finding stock metal reeds. I see composite reeds from CCMS and Boyesen reeds. I see whole reed block assemblies on ebay. What about replacing just the reeds as a set for my 1995 Force 70 hp OE118705? Are they available somewhere?

Hi FWDan, Welcome to iboats!

Inside the following link is a newly released OEM parts catalog for this engine model (H070412RD) for you from iboats though right now it appears they are still a bit behind in getting available OEM parts in stock due to this system is still new to iboats but props to them for finally being able to get in on the act of obtaining OEM parts.... http://www.iboats.com/70-HP-0E000001-THRU-0E138599/dm/view_id.1688129

So with that mentioned, To help try and get things going better, iboats is hoping that if some of the regular helpful members in this (and other) sub-forum sections wouldn't mind taking some extra time at getting to know the new parts look up section from iboats and posting the links like I've done above to members in need.... It would really be appreciated.... http://www.iboats.com/Boat-Motor-Parts/dm/view_id.268656?cm_sp=May2016-_-MarqueeAds-_-OEMPARTS

FORCE

1995

70

Model number H070412RD

70 H.P.

Using either one of the parts link provided above, you should be able to find your part numbers you're in need of and you could either try searching the numbers near the top of this iboats link, http://www.iboats.com/ .....Or try your part number search online if you have no luck here at iboats.

Thanks to you all and good luck.:encouragement:

 

[FWDan]

[FONT=&quot]I took care of the broken OEM metal reed today by installing a new set of CCM sport reeds. The motor starts a lot easier now and idles in neutral on muffs. Before the new reeds, I had to use the fast idle feature (pushing the button in the middle of the control and pushing the throttle forward) to get the motor started and keep it running. The new reeds are definitely a huge improvement to idling.

However, the motor still misses while idling. I put the timing light on plug #1 wire again as described earlier and I still see 1, 2 and 3 near the timing mark. So, I still have the multiple firing per revolution problem. I did not expect new reeds to resolve this issue, but testing again did verify the problem did not change. I think the multiple firing is causing the rough idle.[/FONT]
[FONT=&quot] [/FONT]
[FONT=&quot]My theory: the switchbox is bad causing the plugs to fire 2 or 3 times per revolution. I am a little leery of running the motor too much with this condition for fear of damaging my new reeds. If a cylinder fires when the piston is down and open to the crankcase, could this generate high crankcase pressure and damage reeds?[/FONT]

 

[pnwboat]

Kind of a guess as to whether or not it will damage the reeds by running it like it is now.

One thing is 100% certain....it won't damage the new reeds if you don't run it.

It's your call, but probably not a good idea to run it right now.

 

[FWDan]

[FONT=&#10]pnwboat I agree. I just found this at http://www.outboardignition.com/powerpackworks.asp in their FAQ section:[/FONT]

[FONT=&#10]There are a couple of scenarios that can happen at power pack/switchbox failure. A power pack/switchbox can drop discharge to one cylinder, multiple cylinders, or even all cylinders when completely dead. It can also go into a state of what?s called "double firing". This is when energy is discharged more than once on any given stroke of a cylinder. Unfortunately when this issue happens, serious internal damage can occur to pistons, rings and cylinder walls via detonation (firing the spark plug at the wrong time). How can you tell if this is happening with your motor? Unfortunately, you normally cannot. When a power pack/switchbox is in a double fire state on only one cylinder, there may be a VERY slight miss sensation to detect, but in most cases the miss is ever so slight that the average person would never be able to detect it was happening until it?s too late and the damage done. So how can this be prevented? Other than making sure all ignition components have a good solid ground circuit connection, the words "unfortunately" nothing, has to be used again, because a power pack/switchbox can operate perfectly as designed for an eternity, or they can go bad right after installing them. Sometimes failure is caused by other ignition components, sometimes the power pack/switchbox fails just because. Bottom line, any electrical component is prone to failure at any given moment and there really isn't much anything you can do to prevent it from happening. In the boating world (and probably others), this just has to be accepted as "stuff happens".
​[/FONT]
[FONT=&#10]Looks like I need to replace the switchbox before I run the motor any more.[/FONT]

 

[FWDan]

I just wasted $230. I put the new switchbox in and I still have the double fire/triple fire problem on all cylinders. :grumpy:

​Now what?

 

[FWDan]

Here is a video of my problem:

​I'm not sure if I should just run it as is or try to fix it. Any ideas on what to try next?

 

[pnwboat]

I don't know FWDan, but the motor seems to idle pretty smooth but that's just my opinion based on your video. I didn't see any evidence of a misfire. I would think that if the motor was firing multiple cylinders at the same time, it wouldn't run idle very smooth. I would expect it to maybe backfire and do all sorts of rough running.

I suspect that what you are seeing is a result of the flash of the timing light staying on too long, thus illuminating additional numbers giving the impression that the other cylinders are also firing. The flywheel is spinning (I'm just guessing) at around 800 - 1000 RPM's, so the flash from the timing light may still be present as the next number comes around.

Normally when you're setting the timing, you only mark the numbers around the target area 28? - 32?. Never tried marking the TDC of each cylinder, so I have never encountered the scenario that you have set up, but I would suspect that the results may vary from one particular brand of timing light to another.

I'm not sure of the firing order, but if you notice, when you are checking #1, you also see #2 which is the next number since the flywheel is spinning in a clockwise direction. Also, the number 2 is not quite as steady at the number 1.

When you check #2, you see #3, and again, the number 3 is the next number to come around and it's not quite as steady as the number 2. I can't explain why you don't see number 1 when you're checking number 3, but that may be due to the firing order?

Bottom line is that I don't think you have a problem with the ignition system. Make sure the plugs are not fouled from all this idling and testing and try it out on the water. If it runs reasonably well in the water, I would say that the ignition system is OK. If you have some bogging or throttle response issues, I would look elsewhere.

 

[fmt2bx]

FWDan,

Try to run the same test with the rectifier disconnected and see what you are getting.

 

[FWDan]

I ran the same test with the two yellow wires disconnected to the rectifier. No change.

​If the timing light is staying on too long, I think the numbers would be blurred. I am seeing crisp numbers with no blurring. Since I see extra numbers, I believe I am getting extra timing light flashes. What is causing that? Read on.

I decided to do some additional testing. With motor running, timing light (TL) on battery and TL trigger pulled, I slowly moved the TL inductive pickup toward the #1 spark plug wire, starting from a couple of feet away. At about 6 inches away the TL started to flash intermittently. When the inductive pickup reached about 4 or 5 inches away from the plug wire the TL started to flash consistently. I thought the inductive pickup had to be around the plug wire to work. For my TL, that is definitely not the case. As a matter of fact, when the pickup is on the #1 plug wire, the pickup is only about 2 inches from the #2 plug wire and about 4-5 inches from the # 3 plug wire, close enough to trigger the TL by all three plug wires. I also replaced the plug wires to rule out bad plug wires. There was no change with new wires. It seems that I don't have an ignition problem, but have a problem with timing light pickup being too sensitive. How do I verify this theory? Read on.

I used aluminum foil to create an electrical shielded around the #2 and #3 plug wires and put a jumper to engine ground. With TL pickup on #1 wire, low and behold I only saw only number 1 on the flywheel. This confirmed for me that my problem was due to TL inductive pickup from adjacent plug wires, not from extra pulses of voltage coming down the #1 plug wire. I also shielded wires 1 and 2 and tested TL on #3. Only #3 showed up on the flywheel. It was a little tricky getting a good shield around plug wire 1 and 3 while testing plug wire #2 in the middle, because I did get some intermittent 1 and 3 flashing on the flywheel, but I attribute that to poor shielding.

Finally, I took the boat to the lake this weekend and it ran just fine. I still have to use fast idle to start, even after the motor is warmed up. I will work on that and suspect air mixture screw adjustment is needed. The top end RPM?s seems less than last summer. It was 5000 rpm then and now around 4200 to 4500 rpm. I think that may require a timing adjustment.

Conclusion: I think my ignition is working fine. I suspect a plug will not spark due solely to the energy from and adjacent plug wire, because there would not be enough energy there to create and actual spark. There is however enough energy to trigger the inductive pickup on my timing light creating the appearance of double/multiple firing. In my case, it?s just a timing light problem.

Recommendation: If you get an indication of double firing or multiple firing when performing the timing light/flywheel test, before you spend $$$ buying new switchbox or trigger, make sure you test your timing light inductive pickup for interference from adjacent plug wires.

Please let me know if you think I?ve missed something.

 

[Nordin]

FWDan nice to hear your engine runing as it should.

This is throubleshooting at a high level.
If you are able to borrow or buy another timing light, you can confirm that your test result is a to sensitive pick up.
If you buy a new try to get a "pro" typ if you can afford it.

Your issue with having to use fast idle when starting even if it is warm is not so uncommon.
This can be as you say a fine tuning issue BUT Chrysler/Force have been known as cold blood OB at cold start and even in warm conditions.
Some of them will start warm "only looking" at the key some do not.

I have worked on and owned other brands and they have been the same.
Some will start without fast idle, some not when they are warm.

Try to fine tune as much as you can (timing set, carb adjustment) and see how far you will come.
If you still can not start without fast idle after the tuning......... do not bother about it.

 

[pnwboat]

Sorry to hear that the timing light was the cause, but if it's any condolence, if you had to take it to a marine repair shop, I'm sure it would have cost just as much if not more. So chalk this one up to experience. Regardless, your persistence and common sense trouble-shooting technique finally uncovered the actual cause.

 

[FWDan]

Thank you all for sticking with me through this one. I really appreciate all your help. I learned a lot about my motor that will help me with future troubleshooting and help keep my motor running good. This forum is an awesome resource. I hope others can use what I experienced to help their situation. Thanks again.

 

[roytgarcia]

did you resolve your problem,you said
My symptoms have been rough idle and dies in gear, cutting out at the beginning of a hole shot and not reaching full RPMs (only about 4000rpm) at WOT. At wide open throttle it seems to bog down. Last summer it ran fine.

 

[jerryjerry05]

You posted on an old post that the owner stopped going to.
The best way to ask is start your own new thread.

Start with a compression test and a spark test, post those results??
​And it REALLLLY helps if you tell us what were working on???????