Troy Bilt spark cable problem... maybe?

I have a fairly new Troy-Bilt gas trimmer (TB21 EC) that starts and runs just fine for 3 to 10 minutes depending on how hot the engine is, and then quits. I've noticed that right before the engine quits, it surges a bit, sputters, then dies. It will start up again just fine but then quits shortly thereafter.

I spoke to a guy at technical support who said that the problem was the spark cable. I suppose I should just take his word for it, but the replacement part runs about $60 for a machine that costs $99., and you can't get just the cable, you have to buy the whole "Module Assembly", part #753-05420.

So does this sound like the spark cable to you, and is there any fix other than replacing the whole module?

 

Sounds to me like more of a fuel issue. At least I would eliminate that first. Try loosening the fuel cap when it dies and see if it starts back up and runs longer.
The surging before it dies sounds like a lean condition, or basically, running out of gas.
Check the filter and fuel lines also.

 

I agree with the fuel issue. I am not sure if that model has a float, but that also might be sticking as well which would cause that sudden spike due to air/ful ratio changing.

 

I agree, sounds nothing like a spark issue, but more like a fuel issue. Try loosening the cap as mentioned, then if that doesn't do it, check the fuel lines and primer for cracks and replace if necessary. If still no joy, take the carb apart and clean it or replace the carb.

 

Thanks everyone. It sounds more like a fuel issue to my untrained ears as well. The tech support guy sounded either very confident about the spark cable or he just didn't want to be bothered with my question and "spark cable" was the answer he gave to everything. I'll run it some more today and see if I can see any problem with the fuel line or other fuel issues.

 

Well, I gave everything a cursory inspection and the only thing I could see wrong was that the air filter seemed a bit dirty, so I dusted it off as best I could, and it ran like a champ. I didn't really push it very hard, so I might be a bit premature in my analysis, but right now it looks like a dirty air filter.

So, OK, if that turns out to be the case, explain to me the odd behavior: it runs fine for a while; there is a short surge; it starts to sputter; it quits. In particular, why the surge?

 

The problem isn't the dirty air filter, but the lean fuel condition = surging. Fuel delivery can have variances because of temperature, flexing of the fuel pump diaphragm, and/or the passing of fuel past obstructions in the fuel filter, lines, etc. More than likely you'll come backing to a surging engine until you have cleaned the carb or otherwise fixed the problem with the fuel with a kit, filter, etc..

 

A plugged fuel cap vent can create these symptoms. It can also change by the amount of fuel in the tank. More fuel leaves less air which can cause a vacuum lock much sooner than an almost empty tank.
It is also a problem that can self clear. It may have sucked itself clean, been wiped off while refueling or cleaned by splashing gas in the tank...