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B&S 3.5hp won't spark.. anyone an expert? by JohnnyK
Started on: 02-26-2002 07:38 PM
Replies: 17
Last post by: mbramble on 03-05-2002 05:26 PM
JohnnyK
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Report this Post02-26-2002 07:38 PM Click Here to See the Profile for JohnnyKClick Here to Email JohnnyKSend a Private Message to JohnnyKDirect Link to This Post
I have a 3.5 horiztonal shaft that used to work (decently at best) but at least it would fire, then I left it outside for 1 or two winters and it won't spark.. Any ideas what to look for? I assume it works on a "points" type system.. will rust cause it not to spark?
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DaRkLoRD
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Report this Post02-26-2002 08:02 PM Click Here to See the Profile for DaRkLoRDClick Here to Email DaRkLoRDSend a Private Message to DaRkLoRDDirect Link to This Post
still doing engine work? But I thought you got rid of your Fiero?? (j/k!)

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Black86SE
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Report this Post02-26-2002 11:44 PM Click Here to See the Profile for Black86SEClick Here to Email Black86SESend a Private Message to Black86SEDirect Link to This Post
I don't know if the rust is the reason it doesn't run, but the water and weather couldn't help it much. A tune-up kit with new points and condenser for that motor doesn't cost a lot. I think we used to sell them at work for like $5. It is a cheap thing to try. Did you replace the plug? There really isn't much on those engines that will cause them not to spark. I have rebuilt one a few years ago for a class. Not that difficult, but I bet you will have to pull the flywheel to get to the points and condenser.

Hope this helps.

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Black86SE
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Report this Post02-26-2002 11:45 PM Click Here to See the Profile for Black86SEClick Here to Email Black86SESend a Private Message to Black86SEDirect Link to This Post

Black86SE

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grrrr.

[This message has been edited by Black86SE (edited 02-26-2002).]

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Leadfoot
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Report this Post02-27-2002 12:10 AM Click Here to See the Profile for LeadfootClick Here to Email LeadfootSend a Private Message to LeadfootDirect Link to This Post
Sounds like the points are gone. You can replace them or buy an electronic ignition module that gets rid of the points. My dad bought one for our 8 hp B&S and it worked fine for years. I don't recall where he got it from though.
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JohnnyK
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Report this Post02-27-2002 02:28 AM Click Here to See the Profile for JohnnyKClick Here to Email JohnnyKSend a Private Message to JohnnyKDirect Link to This Post
The thing is it worked fine before I threw it in the backyard.. Must just be corrosion or something.. How much friction does it cause when the magnet rubs by the whateveritis.. I can't tell if it's not enough.. No, it's not the sparkplug, cause I tried the ol' screwdriver trick... (And it's a new sparkplug from last year)..
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JohnnyK
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Report this Post02-28-2002 01:29 PM Click Here to See the Profile for JohnnyKClick Here to Email JohnnyKSend a Private Message to JohnnyKDirect Link to This Post
Anyone know how close the 2 prongs from the coil are supposed to be to the magnet spinning on the flywheel?
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GTFiero1
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Report this Post02-28-2002 02:38 PM Click Here to See the Profile for GTFiero1Click Here to Email GTFiero1Send a Private Message to GTFiero1Direct Link to This Post
 
quote
Originally posted by JohnnyK:
Anyone know how close the 2 prongs from the coil are supposed to be to the magnet spinning on the flywheel?

they ar all different, you'll hve to look it up some where. I got a briggsand stratton 5 horse (wt mods) on my go-kart. i believ my gap is somewhere around 6 thousands of an inch. I wanst getting good spark for a while so i removedthecovr and the damn flywhee was covered in mud and rust, took a steel brush to it and some steel wool and cleaned it up and now i get good spark. Points? this thing dont hve a distrubuter. Anyway my engine is rnnin pretty good now...heh actually (at least for mine) i used a scew driver to push open he throttle a lot more than it is set to go, this thing was screaming (it was on the NOS street performance stuff too)and i let off it quikly ad POP, damn spark plug exploded

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JohnnyK
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Report this Post02-28-2002 11:36 PM Click Here to See the Profile for JohnnyKClick Here to Email JohnnyKSend a Private Message to JohnnyKDirect Link to This Post
Would the coil/magnet on the flywheel be considered electronic ignition? It tells the "points gap" for all non electronic ignition (which they said is most fo them from pre83) but I don't think this motor is pre 83..?
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JohnnyK
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Report this Post03-04-2002 06:29 PM Click Here to See the Profile for JohnnyKClick Here to Email JohnnyKSend a Private Message to JohnnyKDirect Link to This Post
Well, cleaned the flywheel and the magneto coil thing, still no go.. any other suggestions?
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GTFiero1
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Report this Post03-04-2002 10:00 PM Click Here to See the Profile for GTFiero1Click Here to Email GTFiero1Send a Private Message to GTFiero1Direct Link to This Post
junk it. We had a 3.5 Briggs and Stratton on our lawn mower (probably the same thing you have) I just remembered about this as i was re-reading this thread. We tried cleaning everything and replacing somethings but in the end we just got a new lawn mower. Sounds like it may be time for you to put this engine to rest
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Report this Post03-04-2002 10:38 PM Click Here to See the Profile for Master_SushiClick Here to Email Master_SushiSend a Private Message to Master_SushiDirect Link to This Post
I had this happen to a cheap 10hp lawn tractor. Ended up taking it to a small engine repair shop. I have no idea what they did. But after 100$ and a few hours they had it working great. They said they redid the electrical system. But I thought that was BS, its a tractor! What electrical system?
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JohnnyK
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Report this Post03-05-2002 01:20 AM Click Here to See the Profile for JohnnyKClick Here to Email JohnnyKSend a Private Message to JohnnyKDirect Link to This Post
Junk it?! Nooooo! it's horiztonal shaft and those things are expensive and rare! I wonder if I could just find a way to replace the horseshow shaped thing with the coil in the middle, (spark plug wire comes out of the coil) it would work again? The magnet on the flywheel is still, well, magnetized.. hows that work anyways, just the magnetic field causes a spark?
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Fierowrecker
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Report this Post03-05-2002 01:24 AM Click Here to See the Profile for FierowreckerClick Here to visit Fierowrecker's HomePageClick Here to Email FierowreckerSend a Private Message to FierowreckerDirect Link to This Post
 
quote
Originally posted by Master_Sushi:
I had this happen to a cheap 10hp lawn tractor. Ended up taking it to a small engine repair shop. I have no idea what they did. But after 100$ and a few hours they had it working great. They said they redid the electrical system. But I thought that was BS, its a tractor! What electrical system?

Hey Johnny!
Do you have a small wire going to the throttle plate?
Does it get grounded to stop the engine?
See where I am going? If the wire shorts to ground because of corrosion, you get no spark...
Or if your points are glazed over, no spark...
crash...

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JohnnyK
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Report this Post03-05-2002 02:35 AM Click Here to See the Profile for JohnnyKClick Here to Email JohnnyKSend a Private Message to JohnnyKDirect Link to This Post
Hang on.. the actual throttle cable? it's not hooked up.. There is the governor wire, and it's just going somewhere now, I have it out of the way... I don't get what your saying though.. To stop this engine, there is a little lever thing you flip over that touches the spark plug..
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mbramble
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Report this Post03-05-2002 08:02 AM Click Here to See the Profile for mbrambleClick Here to Email mbrambleSend a Private Message to mbrambleDirect Link to This Post
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JohnnyK
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Report this Post03-05-2002 02:09 PM Click Here to See the Profile for JohnnyKClick Here to Email JohnnyKSend a Private Message to JohnnyKDirect Link to This Post
See one thing I don't get is the lever to stop the engine. Looks like all it's doing is grounding the spark plug to the block, but uhh, would the spark plug already be grounded to the block (being screwed in and all?)
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mbramble
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Report this Post03-05-2002 05:26 PM Click Here to See the Profile for mbrambleClick Here to Email mbrambleSend a Private Message to mbrambleDirect Link to This Post
The center electrode is not grounded. The threaded part of the plug is grounded. So the spark is shooting across the air gap from the center electrode to ground.

The stop lever does ground the center electrode so the current is carried straight to ground because that provides less resistance than having to jump across the spark plug's air gap to get to ground.

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