Garage furnace...can't light pilot

I have an overhead gas blower furnace in the garage. I had it serviced last winter when the transformer fried.
Trying to fire it up for the first time this year, and the pilot won't light.
I'm sure that the gas supply valve is open.
I thought maybe I just need to wait for the air to purge after opening the valve, but I held the pilot button down for about 5 minutes, and it still won't light.
Should I hear a hiss or smell gas, or the amount involved in a pilot too small?
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"Mitch@this_is_not_a_real_address.com" wrote:

Careful, here...leaving a pilot on for any lengthy period _can_ result in nasty things happening. Coupla' fellas' out here just blew up/burned down their house day before yesterday trying to purge a line. Darned lucky to be alive.
If you can't smell the gas, there isn't any for one reason or another. Either the valve didn't open or for some other reason you have a problem. One thing that happens here over the summer w/ all small openings is critters such as wasps or other mud daubers or leaf cutters build nests in them. Make sure the orifice is clean and open.
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Thanks.
Here's my furnace: http://www.sterlinghvac.com/html/..%5Clitlibrary%5CIIPLM-BL.pdf
If you're inclined to check it out, the style of my pilot assembly is on page 13.
Should I try removing the hood? These furnaces are ridiculously hard to get around in. I removed the sheet metal bottom in order to access the pilot.
Should I mess with it or call a pro?
I don't have an air compressor, but I have a can of compressed dust remover for computers and electronics.
It's non-flammable. Should I give the orifice a blast?
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If it's accessible easily enough to go sniffing it, it should be easy to see if it can blow bubbles with soapy water. One std way to check for small leaks, very small leaks.
You may just have to manually hold pilot valve open for a while until gas gets to the unit.

J
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Mitch@this_is_not_a_real_address.com wrote:

page 12.

trials (I've found that I sometimes don't get the match flame in quite the right spot to light them when I'm working in contorted positions <g>), I'd opt for the pro.

I doubt it would help.
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Mitch@this_is_not_a_real_address.com wrote:

Are you following the instructions for how to light it?
E.g., with some (most? all?) you need to press the pilot "button" _while_ you try to light it (with e.g. a match), and continue to hold it down once lit until the bimetal valve heats up and it can sustain itself.

After 5 minutes, I would have thought you would smell it. But I haven't always smelled it immediately. People's noses differ.
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Definitely. You have to hold down the spring-loaded red button.
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This is Turtle.
With what you have said here. I will say you have a restriction in the gas flow from the meter outside to the pilot head burner. this can be may number of things like Gas valve somewhere shut and you not know it, Pilot adjustment screw set too low or has trash in the pilot lite needle in the gas valve to set the flow of the gas to the pilot valve, or even to you did not pay your gas bill last month. SO.
When you push the red button you over ride all valves and everything that would hold the natural gas back which tells me you have a restriction of some kind of the gas not getting to the pilot lite to burn.
TURTLE
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Mitch@this_is_not_a_real_address.com wrote:

You may want to backtrack and see if there is another valve that is shut off. Maybe you shut a valve off when you thought you were opening it.
BTW for most of this worlds population the sniff test should be enough. For me, after years of sinus infection and hay fever, I can't count on it. :-)
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It can take a LONG time to purge the air. If nothing else is wrong, that's an IF. IF nothing else is wrong then just be patient. There are dangerous ways to purge the air from the gas line but I wont mention them here. Be careful.

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