I have a craftsman leaf blower model 358.797180 that is 6 years old. It slowly died the other day and I could not restart it. I cleaned the carb yesterday (no rebuild kit, though), and it looked okay (didn't see any varnish, and the diaphram seemed very pliable). It fired up fine then, and I went through 3 tanks of gas over 3 hours or so. Today I tried to start it, and nothing. I tried to check the plug by unscrewing it, leaving the plug wire connected to it, and connecting another wire from the thread of the plug to the threads on the engine. I pulled the cord, and I don't see any spark (I didn't mention - it's a new plug I put in before cleaning the carb). This is my first attempt to check for a spark, so it's possible I didn't do something correctly.

Does it seem likely that I suddenly wouldn't have a spark after running for hours yesterday? If the igniter module is going bad, is it something that would sometimes work and sometimes not? I'm curious if my "fix" yesterday of cleaning the carb didn't really do anything, and the problem is that the igniter is sometimes not working. Any help would be appreciated as I'm clueless what to pursue now (or if it's even worth it at the cost of these blowers). Thanks, Wes

 

I am curious why you went to the trouble of removing the spark plug without unplugging the wire? It is possible that turning the spark plug with the wire attached unscrewed the terminal from the top of the plug or worked the connection inside the boot loose.

 

Hi,

Thanks for your response. I see that I worded that poorly. I should have said that I first removed the plug as normal (took the wire off first). Then, to test it, I connected the wire and boot back onto the plug and connected another wire from the threads of the plug to the threads on the engine. Hopefully that explains it better.

 

If your jumper wire was making a good connection to a metal part of the engine, then I'd say you checked for spark sufficiently. Double check again in a dark area to be sure... sometimes the spark is not so bright or visible. If no spark, the kill switch or coil could be at fault.

 

Thanks cheese. I'll give it another shot this weekend in a darker place. I've also learned about the grounding wire to the coil, so I'll try to disconnect that to see if it will fire then. Any advice on how to identify that grounding wire?

When a coil fails, is it common to be running fine for hours and then the next day just nothing? Just curious if the symptom points to the coil or maybe more the kill switch / grounding.

Thanks again,
Wes

 

The coil probably will have two wires. One spark plug wire and a thinner one that goes to the kill switch. Disconnect the thin wire and make sure the end is not touching anything.

The coil problems I've seen usually happens when the the engine is hot. It will start fine but when it gets up to temperature it starts missing or just totally cuts out. When the motor ran the three tanks of gas was it running perfectly or was it missing, varying in speed or any other symptoms? Hopefully it's something cheap and simple like a bad spark plug.

 

Thanks Pilot Dane. Sounds straightforward on the wires except for one thing... Sorry for what may be an obvious answer, but is it a definite that my blower has a kill switch? To turn it off, I simply press the throttle lever completely down; there's no separate switch. It just came to mind that I saw no wires going to that throttle lever when I cleaned the carb, so I'm not sure if there's an actual electrical kill switch. Here's a link to the igniter module on the sears site:

http://www.searspartsdirect.com/part...0/0247/1503120

Is it certain that there's a kill switch, or is it possible I turn it off simply by starving it of air?

When it ran Saturday afternoon, it ran great. Hummed up to normal speed with no sputtering, skips, or anything through the afternoon. Each time I restarted after refilling the tank it fired right up also. That's the frustrating thing - it really felt like I'd fixed it.

 

You might be right about not having a kill switch. I looked at the parts diagrams on the Sears site and the only wire I see is for the spark plug. I don't see a kill switch or fuel shutoff valve.

 

I recalled one other thing that I did while working on blower Saturday. The cylinder attaches to something (sorry I don't know the term - the block maybe?) with two hex/allen head screws. One of those (I forget which one) was loose, so I tightened that down. The other one felt very solid - I couldn't tighten or loosen it. I wasn't able to wiggle anything after tightening those down.

When it didn't start yesterday, I did not take any of the housing off to get to the engine, so I don't know if it came loose again. I would think it would be highly unlikely to loosen again so quickly but wanted to mention it.

 

I'll reply to this thread since it's the one that helped me.

My blower is a Craftsman 358.794900 175mph blower. For the last several years it's been getting slowly harder to start, and wouldn't run on the no choke setting, it only ran on 1/2 choke.

In retrospect these were both symptoms of one of the cylinder bolts slowly getting loose. I took it apart, took off the cylinder, and the gasket (which is an o-ring style in a groove) was fine. One of the cylinder bolts was indeed totally loose. The piston ring was a bit stuck in the groove so I removed it and sanded the carbon off the combustion chamber side of the ring. On reassembly be carefull as the ring has beveled ends, that fit around a tiny pin in the piston ring groove.

After re-assembly it runs like it was new. Hope this helps someone.

 

May need new head gasket, a lot of times when the vibration causes those bolts to back out the hot exhaust will burn the head gasket. Happened to me on a similar model craftsman. Replaced head gasket, ran like a champ. You can put some locktite on head bolts to help keep them from backing off again.