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Generac Air Cooled Generators Troubleshooting Questions, Answers, and Information About Air Cooled Guardian Generators

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Old October 18th, 2010   #1
ricor
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Default How to bypass an oil sensor to test

I have a 7000kw unit, no sense in telling you the model number as no one can find it, not even generac (it is gasoline/propane). Typical house unit, not portable.

It runs for a minute then shuts off. How do I test the cutoff sensors, like oil sensor? Do I jump the two wires going into it?

What other sensors do I look for?

Thanks!
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Old October 18th, 2010   #2
Dennis
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I think you just need to remove one of the wires off the sensor. When the wires are connected, the enging will shut down. The only other sensor you might have is an over temp and that would be tested the same way. Good luck

ps: I found a manual for a 9067-0. The quality is poor but it is better than nothing. I have the -8 model that has a larger engine than the one listed for the -0. I also found a manual for a 10k that looks a lot like the 8k. If you want I will look for the info and post it here.

Last edited by Dennis; October 18th, 2010 at 09:17 PM..
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Old October 18th, 2010   #3
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"Fail-safe" sensors which are essentially switches would normally be "made" when the applied variable is "normal".

In other words, a low oil pressure sensor is probably a switch which is "made" when the pressure is normal for running an engine.

Opening the wires by pulling a connector off the sensor (which is a switch) would probably emulate an alarm condition. If this is true, then shorting the wires (or shorting a single wire connection to ground) would emulate a "normal" condition.

Before I would defeat a low oil pressure sensor, for example, I would MEASURE the variable and determine if the condition is in fact safe for the engine. For this example, I would remove the pressure sensor from the engine and install a reliable pressure gauge. Then, attempt to start the engine. Since pressure will not build up in the sensor, the engine won't continue to run. However, you should see the oil pressure build up to normal on the gauge if the only problem is a bad sensor.

I can go on and on if you need more.
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Old October 18th, 2010   #4
Dennis
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The one that is close is an 8k not 10k. It is an 0865-0. This has a 570cc engine that my -8 model has. I will look for the download link for the -0 model that has a 480cc engine.

Here is the download link for the 9067-0
http://www.hammerwall.com/Download_Manual/4262/

After it opens you can save it to your hard drive. Again the quality is poor and the engine size may be different but the info should help.

Last edited by Dennis; October 18th, 2010 at 09:22 PM..
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Old October 18th, 2010   #5
Gman1
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In the older units, you could just unplug/remove the wire from the op switch. If it runs, you either have a bad switch...or no oil pressure. On the newer units the switch has to be closed for the engine to crank and then open before the board "looks" for oil pressure. In the latter case, ground the sensor wire, crank the unit, and then immediately un-ground the wire. Hope this helps.
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Old October 18th, 2010   #6
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Quote:
Originally Posted by Gman1 View Post
In the older units, you could just unplug/remove the wire from the op switch. If it runs, you either have a bad switch...or no oil pressure. On the newer units the switch has to be closed for the engine to crank and then open before the board "looks" for oil pressure. In the latter case, ground the sensor wire, crank the unit, and then immediately un-ground the wire. Hope this helps.
I verified this in the diagnostic manual for my 5416. What I said above about "fail-safe" sensors is true, but it's apparent that the sensors - at least the oil pressure sensors - in Generac generators are NOT fail-safe.

A fail-safe system is designed to trip if a wire is inadvertently cut or a connector falls off in the sensing circuit.

In my generator, at least, the oil pressure sensor opens a contact as acceptable oil pressure is reached.

To test the safety circuit, I would put a gauge in place of the sensor and short the lead that went to the sensor to ground. Then, test start the generator while watching the pressure gauge. If pressure starts to rise in a way that seems normal, remove the sensor lead from the grounding connection and the engine should continue to run. Shorting the sensor lead back to ground should cause the engine to fault and shut down.
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Old October 19th, 2010   #7
techntrek
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Actually the newer system sounds better. It tests that the switch changes state (on/off) from before starting to after starting.
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