The Briggs Puzzle

[McGrew 460]

I purchased a used McClane edger a few years ago.  It had a 3hp B&S on it.  Got it cheap since the seller could not get it to start.   I bought a carb kit, soaked it good and put it back together.  It has run like a champ ever since and starts with 2-3 pulls even  after sitting all winter.  I used it a week ago and edged my driveway.  Great edger, but I always thought it could use more power.  I acquired a 5.5 hp Honda, and with a few modifications, this thing is now a beast.  

 

OK the little Briggs is just sitting there on my bench, so I decided to fire t up before figuring out what to do with it.  I mounted it to a small frame that keeps it from dancing around and hooked up a throttle cable.   Removing the throttle cable from the edger is the only change to this engine, and now it won’t fire.  Nothing, nada...  It has fresh non-ethanol fuel (all I use in my equipment), and has spark.  I have the air filter off, so I assume it is getting air, but have pulled the rope until my arm hurts.  It has never even sputtered since I took it off the edger.  It has fuel, air and spark, but won’t hit a lick.  What am I missing? It has compression.  I should mention that after only 1-2 pulls, I smell fuel like it is flooded.   I cleaned and gapped the spark plug and tried to start it without choking it.  Still nothing and still smells of gas.    I hate being defeated by a piece of equipment. It would not be as frustrating if it was not running a week ago,  Thoughts?  Thanks!  Danny

Edited July 8, 2021 by McGrew
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[ebinmaine 67,498]

Did removing the throttle cable put the grounding/off wire to "always on"?

That would keep it from firing. 

[Gregor 4,846]

I have had several cases where I had spark TO the plug, but not THROUGH the plug. Did you check for spark through the plug?

[McGrew 460]

Eric, I think if the grounding wire was shorted, I would not get spark?  This thing has “bit” me numerous times while fiddling with it.  
@Gregor, good suggestion. I will replace the plug but don’t think that is it either.  I have pulled the plug and grounded it to the head while pulling the rope.  The plug fires, but maybe it’s weak?  Another thought I had:  could the coil wire be grounding out where it comes through the engine tins?  I’m guessing this is the original ignition on this 1988 engine.  Thanks for the ideas!  Danny

[ebinmaine 67,498]

I've personally had more than one spark plug that would fire all day happy as a clam OUTSIDE of the engine but not make it run. 

 

For a few bucks it's worth a try. 

[McGrew 460]

Eric,  That is my next change.  It is just frustrating that it ran a week ago.  I think I hurt it's feelings when I took it out of service... Danny

[ebinmaine 67,498]

40 minutes ago, McGrew said:

Eric,  That is my next change.  It is just frustrating that it ran a week ago.  I think I hurt it's feelings when I took it out of service... Danny

Perhaps this is a possibility.

Have you considered putting a pulley onto it so it thinks it's about to power something?

Or perhaps park it right next to another piece of equipment like a generator so it feels like it's part of the crowd.....

[Handy Don 12,230]

7 hours ago, ebinmaine said:

Did removing the throttle cable put the grounding/off wire to "always on"?

That would keep it from firing. 

I like this line of thinking.

My old Craftsman lawn mower Briggs had the kill wiring integrated with the throttle in a bracket on the carb. A bent connector touching the governor link was killing the engine intermittently. I suspect that when I pushed the mower under a stiff bush that a branch had bent the connector.

[McGrew 460]

Don, I will take a close look at that this evening as the kill switch is integrated into the throttle.  But, would that not prevent it from giving me spark?  I assure you it gives me a healthy jolt if I hold the spark plug wire and pull the starter rope...  Danny

[Handy Don 12,230]

1 hour ago, McGrew said:

Don, I will take a close look at that this evening as the kill switch is integrated into the throttle.  But, would that not prevent it from giving me spark?  I assure you it gives me a healthy jolt if I hold the spark plug wire and pull the starter rope...  Danny

Yes, I see your point and not enough juice would not have been my first guess at the problem either.

But a healthy jolt to you may be "meh" to a spark plug!

Another suggestion is to try it with a shot of starter fluid and see if it pops. Also, be sure the choke is working correctly! 

[McGrew 460]

OK guys, I have an update, but no good news.  I was able to confirm that the grounding wire on the throttle is good and functioning.  With the throttle closed, the spark plug will not fire, but anything above the stop position, the plug fires.  I bought a new spark plug and there is no change.  What I question is that after 2-3 pulls, I smell fuel, like its flooded.  So I tried letting it sit overnight and tried again this morning.  I choked it and pulled it one time and then backed off the throttle until the choke was fully open (confirmed visually).  Pulled it 6-8 more times.  Nothing, not even a sputter.  I think I may use it for target practice...  Danny

[Handy Don 12,230]

1 hour ago, McGrew said:

OK guys, I have an update, but no good news.  I was able to confirm that the grounding wire on the throttle is good and functioning.  With the throttle closed, the spark plug will not fire, but anything above the stop position, the plug fires.  I bought a new spark plug and there is no change.  What I question is that after 2-3 pulls, I smell fuel, like its flooded.  So I tried letting it sit overnight and tried again this morning.  I choked it and pulled it one time and then backed off the throttle until the choke was fully open (confirmed visually).  Pulled it 6-8 more times.  Nothing, not even a sputter.  I think I may use it for target practice...  Danny

Before loading up the weaponry, I'd at least give it a squirt of starter fluid and then a pull with choke and throttle both open.

As @squonk has often pointed out, it's harder to get a spark in the pressurized fuel mix than in the open air. I'd also start checking wiring--coil to plug, etc.

Lastly, if the points are not correct, you could be having a spark but not when it'll do any good!

Yeah, grasping at straws a bit....

[Tuneup 1,433]

Sheared the flywheel key???

[ebinmaine 67,498]

3 hours ago, Tuneup said:

Sheared the flywheel key???

I'd just had that thought too. 

 

@McGrew did you try with a new plug?

 

[McGrew 460]

Don,  But blowing stuff up is so much fun and relieves stress!  Seriously, I would not do that.  I WILL get it running.  Oh, and no points.  It has a magneto ignition.  @Tuneup, I guess it is possible the flywheel key sheared, but it was running when I took it off the edger. It should be simple: fuel, air and spark (properly timed) is all/it takes.   I think that is what is so frustrating.  Thanks for all the responses.  I think starter fluid is the next step.  Danny

[Gregor 4,846]

Do you have a model, type number for this motor? It's possible to have magneto ignition, and points.

[Handy Don 12,230]

22 minutes ago, McGrew said:

blowing stuff up is so much fun and relieves stress

That is surely is and does.

Until, after the fun, it's "you're gonna clean up all that mess you made, right?" "Ummm. Wasn't planning on it..."

[McGrew 460]

Eric, Yes installed a new properly gapped Champion RJ19LM.  It made no difference.  I am beginning to think there may actually be something to the “hurt feelings” scenario...  Danny

[McGrew 460]

@Gregor Yes the model is 80202, and Type is 1765-02.  Code (?) is 88120293.  I believe that makes it a. 1988 manufactured engine?Thanks!  Danny

[gwest_ca-(File Mod) 11,045]

Service manual

 

[Gregor 4,846]

Everything you ever wanted to know about your motor, and then some !

[McGrew 460]

Wow, it looks like I have some reading to do...  Thank you @gwest_ca!  Danny