Cajun power
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testing the anti back fire fuel solenoid: remove the solenoid. It's has a narrow two flat "bolt"...I use a slim wrench from router tool. You can also use a slim open wrench...some folks grind them down to make them slim enough to fit. If you have a swissor style wire stripper, you can use that too...most of the small gauge wire strippers have teeth at end for gripping...the solenoid is not hard to remove...it's just a very narrow area to get to those two flats to remove it.Thanks everyone for the replies. I am going to try and find a mobile person to come and do it for me. Could expand a bit more on the solenoid please. That is not the starter solenoid, right?
Anyway....twist it off. gas is probably going to leak everywhere out of the bowl. Make sure you turn the fuel cutoff valve to prevent fuel spilling everywhere. Or just crimp the line to prevent fuel flow.
put key in ignition...and then slowly turn it and watch the small pin on the fuel solenoid (you just removed it). Does the pin retract back into the body of the solenoid? if it doesn't clean it up with some carb cleaner or brake cleaner....make sure the electrical connector is securely connected AND the ground wire is still attached to the engine...mostly likely the ground wire is attached to a carb bolt. After you clean it up, try the test again and observe. If you cannot get the pin to retract into the body when you turn the ignition key...you have a bad solenoid.
it is a common point of failure..especially with old gas that finds its' way to the needle in that solenoid and then into the solenoid itself...causing corrosion...rust...gum..you name it.
there are two ways to solve a bad solenoid: buy a new one, or just remove it and put in a fine threaded bolt into the bowl to secure the bowl. But if you opt for the latter, make sure the solenoid wires are joined together (completely the circuit) and is terminated at engine ground. Anywhere on the engine is fine...you can use the same carb bolt ground. This eliminates this solenoid as a common failure component from your system. The engine will still operate without it. The engine will still shut down correctly. If you are concerned with excessive fuel draining into the carb after shutdown...then install a fuel shutoff valve close to the carb and use that each time you shut down the engine.
this is what I have done with all my mowers. All of them. These solenoids are just poorly designed. The idea is good, but the engineering was never good enough to prevent fouling from long term storage and old gas contamination..and oxidation/corrosion. A better approach would have been to make the anti back fire device with better material protection against the effects of gasoline and corrosion. But this would have added expense to the design...and as you will probably notice if you shop around even with the current design, they are not exactly a cheap part to source.
here is a youtube video that explains the operation of the fuel solenoid.
You can use this method, but I would NOT recommend the 9 volt battery method.
If you understand HOW to troubleshoot from a logic frame of reference, then yes the 9 volt can tell you the device is good or bad. And if it does test normal (retracts when given 9 volt power), then you can proceed to find where in that circuit the problem exists (why the circuit is not providing power). However, as stated above, because this device is a common point of failure and does not contribute to the operation of your mower...It's entirely up to you if you think it is worth testing and replacing. I prefer to just delete it from the carb...but make sure as stated above that the circuit still is connected directly to a ground. Otherwise you will never be able to start the mower. The fuel solenoid circuit is REQUIRED for starting the mower...electrically this is true. So make sure if you delete it from the carb, you still have that circuit completed to ground. One simple way to do this? just move the ground wire from the one side of the connector and splice it to the power lead on the other end of the connector. This gives a direct path from power to ground. This completes the circuit (acting the same way that an electrically powered solenoid would complete a circuit to ground!). You don't really need a solenoid dangling around near the engine zip tied somewhere...rememeber...it's a common point of failure...just get rid of it entirely! these are only my own opinions. I do this for all my mowers and small engines that have these anti back fire fuel solenoids. They are unreliable. I don't want to spend time chasing gremlins and waste money on devices that really do not make improve the operation of the machine. just make sure to install an inline fuel cutoff valve close to the carb. and turn that off to prevent flow of excessive fuel into the carb! simple..easy peazy.
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