I am trying to fix a Carrier Model 58GS125-2 with spark ignition.

Thermostat Switches on Heat
Spark Starts
Pilot Lights
After about 10 seconds Burner Starts
After about 10 more second Burner goes out
Pilot stays lit and burner keeps cyling on and off with no blower.

Extra info. 3 Wire Pilot assembly, and blower works in "on" position.

Somebody suggested cleaning/sanding flame sensor... is this the same as the part as the sparker (electrode)?

Any Help?

Thanks!

3 wire pilot needs to be cleaned by removing it and clearing the pilot burner, and the pin hole orifice a weak pilot flame will pull away from the bimetal element when the main burner comes on and this will cause short cycling .

Make sure to gas leak test we don't want any accidents

Thanks for the advice. I will give that a try. I cleaned the flame sensor, but this did not change anything. The pilot flame looks good to me (blue flame), but what you're saying makes sense.

There is also a very good chance the auto pilot simply needs replaced if cleaning it doen't work.

Thanks for the replies. It turns out that cleaning the pilot did work. I started on the wrong track. I thought the sparker was also the flame sensor, so I cleaned that.

Once the pilot was cleaned, the furnace worked like a charm.

Hi, I have a similar furnace
Model number is 58GS125-JA 160 series
I can't seem to locate the flame sensor
I've read that it is usually located on the far left side of the burners and apparently should extend directly into the flame of the left side burner, but I can't seem to find one for this furnace.

At any rate I removed and cleaned the pilot light on my furnace and it seems to also have fixed my problem. However, I would also like to replace the flame sensor
If I can find it.

Thanks for any help you can give me

In the model I had, it turned out there wasn't a flame sensor. The igniter had a bi-metal sensor built into it that shuts off the pilot, and keeps the burner going.

When I cleaned the pilot/igniter that resolved the issue, and there was no flame sensor to clean or replace.