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Redmax EB431 no spark


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06-04-09, 09:08 PM   #1  
Redmax EB431 no spark

Hello everyone,

I think I know the problem here but I need a second set of eyes on it. I have a 12 year old Redmax EB431 which has been running fantastically until today (starts on first pull, has good power, no smoke, good compression).Today I started the blower, it ran for about 2 seconds and then just died.

I checked for spark - nothing. The resistance on the secondary coil is about 2k ohms. The resistance on the primary coil (they're physically separate coils on this unit) was around 53m ohms. I took the kill switch out of the picture to make sure that wasn't malfunctioning - still no spark. I took a look at all of the wiring and noticed that the plug wire has a pretty deep gouge in it - deep enough to expose the conductor - but it still conducts electricity. I tried putting the spark plug on a known-good machine (a power washer with a Tecumseh HM80) and it produces a good spark.

At this point, I'm thinking I should replace the secondary coil (if for no other reason to replace the spark plug wire). I couldn't find any coil testing procedures or specifications online and I'd like to get the opinions of some people that see these things every day (or at least in the past have seen them every day). Not only that, but the primary coil is like $75 and the secondary is $50. I don't want to blindly replace parts.

Is there anything else I should try before I replace the secondary? The engine is completely off the blower right now and is fully accessible.

Thanks!!

- Joe

 
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06-04-09, 09:25 PM   #2  
Are you making certain that the plug is grounded to part of the engine when checking for spark? (just making sure before talking part replacement).

I don't have any diagnostic procedures for that either. I'd say if the unit is worth $125, then replace the secondary coil first and if no-go, replace the other as well. The secondary sounds like it could use replacing anyway because of the wire. If the secondary is all that was wrong, you get by with $50 only. I hate doing things that way, but sometimes it's easier and cheaper if you count time to not have to hunt down diagnostic procedures that are usually vague anyway, and often say the same thing (replace one with a know good unit, if still no spark, replace the other). In fact, I've seen that on a lot of ignition system diagnostic procedures straight from the manufacturer.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

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06-04-09, 09:42 PM   #3  
Hi Cheese,

Yup, I grounded the plug on one of the aluminum cooling fins - no spark. I made sure the engine ground/mounting screw was tight and that there was no corrosion.

Sounds like I'll start looking for a coil. Do you know any good places to get used coils? Do you think it is likely that a dealer might have a used one laying around or are these units too old?

Thanks,

- Joe

 
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06-04-09, 10:06 PM   #4  
It's worth checking, you never know. Some dealers keep all kinds of old stuff like that, others don't hardly keep any old parts at all. You never know until you check.


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07-27-09, 05:46 PM   #5  
Well, the new ignition coil arrived and there is still no spark.

The coil near the flywheel (coil 1) has two wires - a red and a black. The black wire attaches to one lead that goes to the kill switch. The other lead from the kill switch gets grounded on the engine.

The coil the plug attaches to (coil 2, the one I replaced) has one wire - red (which attaches to the red wire from coil 1) and a brass connection point that also gets grounded to the motor.

The strange thing here is that I get a shock (but no spark) if I touch the black wire from coil 1 and the motor.

Does anyone know how these two-coil setups work? I've never seen one before now. Can anyone think of anything else this could be before I spend $75 replacing coil 1?

Thanks,

- Joe

 
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07-27-09, 08:02 PM   #6  
I have the same problem with a shindaiwa trimmer with the same setup. They don't give much in the way of diagnostic procedures normally for this type system. I've seen some literature that said to replace one component with a known good unit and if it still doesn't work, replace the other.


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07-28-09, 05:41 AM   #7  
Hehe you have to love it! A single coil setup must have been too simple for these guys

I'll do a little more digging and let you know if I find anything.

Thanks,

- Joe

 
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07-28-09, 07:43 AM   #8  
Well, the two coil mystery has been solved. I didn't realize this machine had CDI ignition.

I'm taking an educated guess that the CDI module is built into what Redmax calls the "Source Coil" for the following reasons:
1. The "Source Coil" has 2 wires - black and red, and a ground through the laminated core. I'd expect a "dummy" inductive coil to only have one wire and a ground connection.
2. I was shocked when I bridged the black wire to ground, but not the red wire (which connects to the red wire of the ignition coil). Black to ground shows significant voltage when the engine is turned, red to black shows almost nothing, red to ground shows almost nothing.
3. Process of elimination - the ignition coil was replaced but the problem is not fixed. The rest of the machine was searched for CDI components and none were found.
4. The "Source Coil" is $25 more than the ignition coil - perhaps the additional cost of the CDI components.
5. The ignition coil shows no signs of having a capacitor in there and it has the number of connections I would expect for a simple transformer - a common ground, and one lead for each coil (red wire for the primary, plug wire for the secondary)

#2 above suggests that the CDI portion of the "Source Coil" may be bad.

I realize that this is far from scientific, but given the lack of available diagnostic information, this seems like a reasonable conclusion. Would you agree, Cheese?

Thanks,

- Joe

 
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07-29-09, 12:56 AM   #9  
#3 being the most influencing factor. If one component of two doesn't fix it, then I'd expect the other to. The air gap is correct, the plug is good, and it is grounded to the engine when checking for spark, correct?


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07-29-09, 05:37 AM   #10  
Yup - air gap was about 7 thou (from the factory), I swapped plugs from an engine with a known good plug and the plug was grounded to the motor.

Thanks,

- Joe

 
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02-03-10, 10:08 AM   #11  
I know this thread is old, but I just wanted to follow up in case it helps someone else.

I didn't want to shell out $75 for a new source coil for an older machine so I waited until one appeared on eBay. Got one for $33 shipped, installed it and the blower fired right up! Problem solved!

Thanks, cheese!

- Joe

 
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02-03-10, 06:14 PM   #12  
Glad you got it fixed! Thanks for updating the thread!


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