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Goldrush


The liberty of expressions sometimes are ridiculed!

Location: St-Hubert Qc. Canada
Joined: Jan 10, 2005
Points: 117

Could a cracked spark plug boot make a backfire?
Original Message   Feb 10, 2005 4:14 pm


Replies: 1 - 10 of 10View as Outline
MountainMan


Overpowered is Usually Adequate


Location: Connecticut
Joined: Feb 19, 2003
Points: 1564

Re: Could a cracked spark plug boot make a backfire?
Reply #1   Feb 10, 2005 5:37 pm
I would say it would contribute greatly to running rough. The spark could be much weaker without good insulation. But backfire?? Id think that is more a issue with Timing.

Ariens 1128PRO- Honda Generator_ Husky 480-257 Jonsered 2050Turbo- Shindiawa T2500 SCAG Mower -little wonder blower-Sears track blower-Coleman Generator- Bombadier ATV-Stihl HS-45 Etc-Etc-Etc
MountainMan


Overpowered is Usually Adequate


Location: Connecticut
Joined: Feb 19, 2003
Points: 1564

Re: Could a cracked spark plug boot make a backfire?
Reply #2   Feb 10, 2005 5:38 pm
That is a Bobcat, Corect?

Nice Condition

Ariens 1128PRO- Honda Generator_ Husky 480-257 Jonsered 2050Turbo- Shindiawa T2500 SCAG Mower -little wonder blower-Sears track blower-Coleman Generator- Bombadier ATV-Stihl HS-45 Etc-Etc-Etc
Goldrush


The liberty of expressions sometimes are ridiculed!

Location: St-Hubert Qc. Canada
Joined: Jan 10, 2005
Points: 117

Re: Could a cracked spark plug boot make a backfire?
Reply #3   Feb 10, 2005 6:23 pm
IT's a Viking single stage from MTD sold by Eaton in Canada in 1974 it runs a Tecumseh 7hp snowking engine very powerfull

buttlint


Joined: Oct 14, 2002
Points: 791

Re: Could a cracked spark plug boot make a backfire?
Reply #4   Feb 10, 2005 7:18 pm
Rush,
The cracked boot wouldnt make a difference....but maybe what cracked the boot would also have cracked the plug?
If it was a resistor plug....it would most certainly cause backfiring.
I cant see what plug you have...but if it is something like a Champion RJ19lm....that would be the first thing too suspect.
Those resistor plugs have a (?) resistor that looks like a tube inside the ceramic insulator. It  also has a little spring underneath the resistor.
The outside of the plug and the electrode can look perfectly fine....but if the spring is broke or burnt up....they backfire all over the place.
I get rid of the resistor plugs when I can...but I dont live in Canada....where they frown on such practices.
But changing the plug is a good and inexpensive way too start.
snowshoveler


tides in dirts out surfs up

Location: bridgewater nova scotia...aka the swamp
Joined: Jan 3, 2003
Points: 1261

Re: Could a cracked spark plug boot make a backfire?
Reply #5   Feb 10, 2005 7:23 pm
we could use a little more info on the problem...

backfire when ,

high speed

low speed

when attempting to start

when stopping

all the time ...

not trying to be a wise crack .but many possibilities here .and we can help.

later chris

craftsman 10/28 snowblower with tracks   husky 372xpg chainsaw   sachs dolmar bc212 bushsaw   mondo trimmer   monster tractor with trailer    cheep wheelbarro and couple shovels and a partridge in a pear tree 
Majorxlr8n


Location: Freehold NJ
Joined: Aug 6, 2003
Points: 1092

Re: Could a cracked spark plug boot make a backfire?
Reply #6   Feb 11, 2005 12:55 am
Points or condensor problems could cause backfire, as well as a grossly mis-adjusted carb. I agree, a bad boot won't cause backfiring...

Marty

viking


Joined: Feb 11, 2005
Points: 4

Re: Could a cracked spark plug boot make a backfire?
Reply #7   Feb 11, 2005 2:08 pm
No but it could affect simply idle speed

terrapin24h


The more I learn the less i know

Location: Rochester NY, USA
Joined: Dec 18, 2003
Points: 628

Re: Could a cracked spark plug boot make a backfire?
Reply #8   Feb 11, 2005 2:40 pm
I would think a weak spark  regardless of the cause could contribute to backfiring, but probably not be the sole cause of it.  If your spark is weak, there is a chance you are not getting a full burn of air/gas in the cylinder, allowing some of the unburned to get to the muffler and POP!  Kohler engines are known to back fire/pop if you don't "idle them down" prior to shutting them off.
This message was modified Feb 11, 2005 by terrapin24h


--chris
2001 Homelite VacAttack Blower
2001 6hp Toro PPace 22" mower
2001 Ariens 824LE
2002 6hp 2400 PSI Excell Powerwasher
2004 18hp Craftsman 27375 42" mower
2004 42cc Craftsman 18" chainsaw
Gelid


Location: Maine
Joined: Nov 19, 2007
Points: 84

Re: Could a cracked spark plug boot make a backfire?
Reply #9   Dec 14, 2007 11:36 pm
Speaking of spark plug and backfiring until this evening I did not know that a dying plug could be the main cause of surges and backfires. I was clearing the heavy snow we got last night when after about 2 hours of strenuous but uneventful blowing my trustful Honda started running real rough with surges, backfires and exhaust flashes. It kept doing this regardless of throttle settings, even on full choke (I know, should've seen the huge red flag). Time to clean the main jet I thought, so I let the machine cool off and had coffee then took the bowl out, spayed the jet and nozzle with carb cleaner and finished the job with the tiny wire, which came out clean. Hmmmm. Screwed the bowl back on and turned the key.

Ran great for about 10 seconds then back to backfires, surges and flashes. Dang, must be some gummy stuff inside the carb. Took the whole carb off which isn't that easy on the HS928 especially when working with gas soaked frozen fingers (new garage not heated yet and it was like 2 degrees out there), brought it indoors for close scrutiny: sparkling clean. Not what I had expected. Fuel strainer was pristine as well. I was vaguely considering dismantling other stuff by then but didn't really know what to look for. My wife asked if I had checked the spark plug. Please don't concern yourself hon, this is serious guy stuff I thought but just mumbled something about spark plugs not causing these symptoms and such (what did I know). However after making sure wifey wasn't watching I did go out and took out the plug, both the electrode and insulator were jet black. Nevertheless I didn't think much of it but cleaned it for good measure and put it back, along with the carb,  and  started the engine. It ran perfect.

WTF?

I have no idea why but it appears that the "coked" spark was the cause of all these symptoms. So now I'm asking myself -and you guys- how can one tell for sure that running rough is not caused by a carb issue? Check the plug first? Gotta get new plug tomorrow. Storm coming.           

Honda HS928 TCD - If you lived where I live you'd have one too
nibbler


Joined: Mar 5, 2004
Points: 751

Re: Could a cracked spark plug boot make a backfire?
Reply #10   Dec 15, 2007 8:17 am
I'd go with checking the plug first, it kind of easier to remove and put back than the carburetor.

The basic troubleshooting process for an engine is Air, Gas, Spark. You have to have all three so check them, the order is up to you and your suspicions but I go easiest/fastest first.
  1. Gas tank full with good gas;
  2. Throttle on;
  3. Ignition key in;
  4. Check spark plug;
  5. Check plug is getting electricity;
  6. Primer working OK;
  7. Fuel lines;
  8. Carburetor;
  9. Compression;
  10. Stare at it and use mental persuasion;
  11. Take to shop and pay big bucks to find out what I missed.
Good luck, hope its something in the low numbers and not the highest.
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