Diesel_Dude08
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- Joined
- Jan 22, 2021
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- 11
Hello this is kind of the sequel to another post I made about a week ago regarding a predator 9500 generator backfiring on shutdown. I have been working on the unit for a family friend. He asked for a full service and a few repairs. One of his complaints was that the generator backfired on shutdown when flipping the shutoff switch. On these generators there are 2 ways to shut them down.. 1:Turn the fuel valve on the front of the generator (proper way according to the manual. 2: Flip the electric shutoff switch (manual states emergency use only.) The customer claimed he had always shut it down using the electrical shutoff switch instead of doing it the proper way. He claimed it started backfiring occasionally on shutdown a couple months ago and now it backfires every time he shuts it down. Generator has 1,690 hours on it and figured a valve adjustment would get back to normal. After the full service (including valve adjustment) the generator would still backfire when it had slowed completely down and was hot.
Because it backfires when the engine has practically come to a stop, and only when it has time to get warm, I assumed it was fuel related. I tore into the carburetor to clean it during the service and the float was not stuck and neither was the solenoid at the bottom of the bowl. I assumed the solenoid had failed internally and was not shutting off the fuel on shutdown like it should. In one of the videos, you can see me testing it with a 12v battery hooked up to my powerprobe. Thanks to some help from ILENGINE on my other forum, I found out that the anti-backfire solenoid runs off power from the generator on shutdown rather than battery voltage like is commonly seen on other small engine applications. In the other video, you can see that it gets plenty of A/C voltage on shutdown but doesn't necessarily continue to provide adequate voltage all the way until the engine stops. Do you guys think it's providing enough voltage until the engine stops? If not, what would be causing this?
What could potentially be the problem here?
Any further diagnostics I could use?
Any thoughts or help is appreciated
Thanks for your time!
Because it backfires when the engine has practically come to a stop, and only when it has time to get warm, I assumed it was fuel related. I tore into the carburetor to clean it during the service and the float was not stuck and neither was the solenoid at the bottom of the bowl. I assumed the solenoid had failed internally and was not shutting off the fuel on shutdown like it should. In one of the videos, you can see me testing it with a 12v battery hooked up to my powerprobe. Thanks to some help from ILENGINE on my other forum, I found out that the anti-backfire solenoid runs off power from the generator on shutdown rather than battery voltage like is commonly seen on other small engine applications. In the other video, you can see that it gets plenty of A/C voltage on shutdown but doesn't necessarily continue to provide adequate voltage all the way until the engine stops. Do you guys think it's providing enough voltage until the engine stops? If not, what would be causing this?
What could potentially be the problem here?
Any further diagnostics I could use?
Any thoughts or help is appreciated
Thanks for your time!
Whoops! 
that’s what I meant