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Honda HT3813 Won't Start


sst4270's Avatar
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06-13-09, 02:24 PM   #1  
Honda HT3813 Won't Start

Hi,

I just purchased a Honda HT3813 today from an individual.
I started it at the point of sale and it ran, but then it cut off.
It would not start again. I still purchased it thinking it was likely something minor.

It turns over fine, but does not seem to be firing.
I disconnected the kill wire from the coil and using an ignition coil tester I get no spark in the window of the tester.

My question is this: Does this absolutely mean the ignition coil is bad or could something else cause the ignition coil to fail this test?

Any advice would be appreciated.

Thanks,

Steve

 
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06-13-09, 03:37 PM   #2  
Given a good tester, and everything is done properly, the other possibilities are: the module isn't grounded or the plug wire is bad. On an engine with an ignitor the ignitor is a possibility.

The ignitor is an electronic substitute for the points. It would provide a switching function from ground to no ground to allow the coil to fire. With an ignitor in the ignition the wiring to that component would have to be considered.

A high percentage of the time the problem is the module/coil.

On the older units with the points and condensers, or the battery/coil/points/condenser, there were more possibilities.


Last edited by marbobj; 06-13-09 at 03:59 PM.
 
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06-13-09, 03:50 PM   #3  
I would say your test safely diagnoses a bad coil since I don't believe you have an ignitor.

 
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06-13-09, 03:57 PM   #4  
I'm with BFH, I looked up the parts list for a 3811 and it only shows a coil for the ignition.

 
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06-13-09, 08:40 PM   #5  
The 3813 has the liquid cooled 2 cylinder engine. I think it has 2 coils if I remember right, but I can't swear to it. Does yours have 2? Are both not firing?

After thinking about it, maybe it only has the one coil and it just fires both plug wires at the same time. I have an engine from one at the shop I could look at.


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God bless!

 
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06-14-09, 05:17 AM   #6  
Won't Start

Thanks for the replies...

No ignitor. Just a single coil with three wires. 2 go to the plugs and one is the kill wire.

The coil is mounted on the rear of the engine behind a big plastic cover. It was a real pain to get to.

I checked both plug wires with the tester and neither had a spark.

With the kill wire disconnected that effectively isolates the ignition from the rest of the electrical system as I understand it. So any failure determined after that point confirms the ignition's status. I just wanted to be sure before spending the money. It's about $100.

I'll let you all know how it turns out.

Steve

 
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06-14-09, 08:44 PM   #7  
While you're behind that engine cover, take a good look at the timing belt. It's probably in need of changing by now unless it's been done already. Most all the ones I've worked on lately needed a timing belt. They are getting old and the belts are cracking/teeth coming off. I think it runs around $90 and the water pump pulley teeth also get worn down pretty bad, so it might be a good time to look at that while you have it that far apart.


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06-15-09, 04:15 AM   #8  
timing belt and water pump

I looked at the timing belt and water pump pulley when I had the cover off and both appear to be in good shape. So they must have been changed at some point in the mower's history.

Thanks for that suggestion.


Steve

 
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06-24-09, 07:44 PM   #9  
are you sure that's a kill wire?

i;ve got a 3813 that i just pulled the flywheel off to replace the timing belt so i'm familiar with the transistorized magneto coil
on it

i'd suggest re-connecting the wire you disconnected, with the plugs out, insert one plug into one of the ignition leads, and lay the plug so the threads are in good contact with the head or valve cover for a good ground, and turn a the engine over and see if you've got a spark at the plug

if not, and you want to confirm the coil is bad, email me and i can scan the honda svc manual page with the continuity check for the coil - there are two, one for primary and one for secondary - believe the coil is about $90 if you do need one

in case, just as an fyi, there's a safety switch in the seat, that if it's bad, it kills the engine - pop the seat forward and you'll see the connector under the seat - you can jump the chassis side of that connector for testing purposes

if you do pull the ign coil off, when you re-install, the gap between the coil (both legs or sides) is 16 thou (+/- 8 thou) per the svc manual (i had to re-install mine after the timing belt change and just did it last week, so it's still fresh)

 
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06-25-09, 06:59 AM   #10  
sorry - gap adjustment for coil should have said, gap between coil and the flywheel should be 16 thou (+/- 8 thou) and be sure to not adjust that gap with the epoxied magnet under the coil, but rather between the coil and flywheel itself

 
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