FD620 carb

[guyfox]

Just wondering if there is any way to check to see if the fuel shut off solenoid (backfire solenoid) in the carb is working properly before I go spend $140 Canadian for a new one. Fuel is good to the carb and there is spark on the plugs but not running. Put fuel down the carb or in the plugs and she will just burn off the fuel.

Do not want to cut the tip just to learn the hard way that was not the problem.

[thorn]

When I bought my Conquest it had been sitting a long time and my solenoid needle was stuck forward. I unplugged it and removed it from the carb. I then sprayed copious amounts of carb cleaner around the needle while working the needle in/out with some needle nose pliers until it was free/loose. You may want to try soaking it over night in some seafoam and then work it around.

You could also troubleshoot it by removing it and plugging the hole it was in with the proper sized nut and then see if your machine runs w/o it in the carb.

[guyfox]

Thanks for the advice. I did not think about plugging the hole with another nut to see if that works...... Now time to go take the carb/solenoid apart again.

[plott hound]

just eliminate that stupid solenoid altogether.will save yourself a lot of grief.

[Canadian_Zuk]

You can also just pull the small O-ring off the end of the fuel shutoff solenoid to see if thats the problem. With the O-ring removed the fuel will not shut off.

[guyfox]

Plott hound, Are you saying that you do not need the solenoid at all?

[plott hound]

I disabled it on my old conquest.its only there 2 prevent dieseling or run on.

[beagle man]

I could be wrong but I think it also prevents fuel from loading up the engine when its not running. Parked facing down hill with a full tank or trailing, kind of prevents the siphon effect.

[Buzz]

You could always take it out and test it. If you do, put 12V to the solenoid to make sure that the plunger retracts like it should. It's there to prevent after-fire when the engine is turned off. Anti-fire solenoids block fuel to the main jet when the ignition is off so that as the engine winds down, the gas that would otherwise be pulled into the cylinder..isn't allowed to do so. The gas would otherwise be sucked in and pushed out the exhaust where it can ignite in the muffler. Most engine manufacturers will recommend and idle-down period prior to shutoff to help in preventing this. Some additionally recommend shutting off at 3/4 throttle or higher because the anti-fire solenoid may only block the high idle side. If you do remove the solenoid and experience backfires, I've been able to prevent it by pulling the choke to make the engine stumble, then turn off the key. It does prevent backfire, but the hot engine may be difficult to restart immediately.
I would make sure your carburetor bowl is actually full of gas? I repeat this alot, but I will frequently use a boat primer bulb in-line to make sure the fuel line is primed and that when the bowl is full, the inlet needle and seat are closing properly. It's a low-pressure system, so you can feel it easily by squeezing the primer bulb.
Before going much further I would make sure that your fuel line is primed and your carburetor bowl is full of gas. If you still have problems, then look a little further.
Sometimes it's easy to think there's adequate gas to the carb when there really isn't. Hope that helps.

[Canadian_Zuk]

I could be wrong but I think it also prevents fuel from loading up the engine when its not running. Parked facing down hill with a full tank or trailing, kind of prevents the siphon effect.

Yes, a side effect of its function, in the event your needle and seat do not fully close the fuel cut off solenoid will prevent your crank case from filling with gasoline through the main jet.