Spark and fuel, but no fire

Reply

  #1  
Old 03-04-06, 04:47 PM
Member
Thread Starter
Join Date: Mar 2006
Posts: 4
Question Spark and fuel, but no fire

I have a Shindaiwa 500 chainsaw ~12 yrs old that is used infrequently. It has really never been easy to start, but over the last few years will only start once or twice a season and only after sitting for weeks/months. Once started, it runs fine; but if it ever is turned-off, it won't restart.

Today, I changed the plug, changed the fuel, and adjusted the carb based on the instructions I found on this site (tried both High and Low screws at 1-1.5-2 turns open) and several combinations thereof. No dice. When testing for spark, I did notice fuel spraying from the cylinder during cranking (which I assume is too much) and fuel also leaks from the muffler (again, I assume that is BAD). It won't even start after leaving it for hours with the plug out to let the fuel evaporate. I also partially disassembled the carb (short of pulling the needle). Everything looks great, no evidence of any build-up. It looks brand new.

About three years ago, I had the saw worked-on to address the problem. I can't remember if he replaced the carb or not. It worked for the next 3-4 times I used it and then fell back into the same old problem.

Any ideas???
 
Sponsored Links
  #2  
Old 03-04-06, 06:25 PM
v8driver's Avatar
Member
Join Date: Sep 2005
Posts: 767
What about compression? Was that checked?
 
  #3  
Old 03-05-06, 12:01 AM
cheese's Avatar
Forum Topic Moderator
Join Date: Jul 2001
Location: USA
Posts: 16,814
Sounds to me like the carb is in need of reconditioning. I imagine either the needle is not sealing, and/or other parts inside are failing.
 
  #4  
Old 03-05-06, 02:24 AM
Bigwind's Avatar
Member
Join Date: Nov 2004
Location: The Panhandle of Florida
Posts: 167
I agree IF you have good compression then it is the Carb. I bet you'll find the screen partially clogged, grit under the needle and a hardened main metering diaphram. The price of a carb kit ranges from $7.50 to $16.00 (Usually). You can't go wrong rebuilding the carb. If you've never rebuilt one it can be a bit intimidating but easy to learn and chances are good you'll get a real thrill when it cranks up on the first or second pull. I learned from asking questions right here on the forum! Good luck, Ron
 
  #5  
Old 03-05-06, 10:59 AM
Member
Thread Starter
Join Date: Mar 2006
Posts: 4
Compression?

I did not check compression - How do I?

I'm thinking you might be onto something because this saw actually siezed-up once. I just let it cool-off for a few days, broke the piston loose, and it ran fine. This problem did pop-up after that incident, though.
 
  #6  
Old 03-05-06, 04:01 PM
v8driver's Avatar
Member
Join Date: Sep 2005
Posts: 767
Just have someone take a compression testor, and have it tested, over 100 is good.
 
  #7  
Old 03-19-06, 06:17 PM
Member
Thread Starter
Join Date: Mar 2006
Posts: 4
Still working on it...

Autozone will loan you a compression tester. Mine checked-out at 60. So, I tore it apart and found that the siezing had done some pretty serious damage to the piston and rings - jug looks good.

Now I'm in the middle of a parts search. Seems Shindaiwa has obsoleted a lot of parts for this saw.

Thanks for your help, guys. I'll tell you if I ever get it running again.
 
  #8  
Old 03-20-06, 12:30 AM
cheese's Avatar
Forum Topic Moderator
Join Date: Jul 2001
Location: USA
Posts: 16,814
Keep an eye on ebay...I see a lot of obsolete parts sold there.
 
  #9  
Old 05-06-06, 06:33 PM
Member
Thread Starter
Join Date: Mar 2006
Posts: 4
Finalllllly...

I found the piston and rings by contacting a dealer in Oregon. The distributor out there still had parts - probably because Shindaiwa is HQ'd in Oregon. I used the original jug ($200 for a new one) and had it honed-out.

Anyway, I rebuilt the motor, re-adjusted the carb and it started and ran nicely. After I shut it down, it wouldn't restart again. I'm hoping that I'm not back where I started, but for now am happy that the saw ever ran again after I had it completely disassembled.

I'll probably buy a carb rebuild kit (if I can find one) and try that next.
 
  #10  
Old 05-31-06, 01:54 PM
boman's Avatar
Member
Join Date: May 2001
Location: North Alabama, USA
Posts: 487
next time it "locks up", try removing the plug and pulling the rope a few times to expel gas in cylinder. Be sure to tape plug wire or make sure it can not fire! Strange feeling when fuel sprays out of cylinder when the plug makes a spark . Be there, done that. Hvae had mowers to fill with fuel and feel like they were locked. And in a way, they were. Piston has nowhere to go when it is full of fuel.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes