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Rick
Rick, Factory Authorized Trainer
Category: Small Engine
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Experience:  Outdoor Power Equipment technical trainer since 1990, covering eight states.
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Engine OHVI Guardian Model GH-410 13/15 HP on a Generac 7550

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Engine OHVI "Guardian" Model GH-410 13/15 HP on a Generac 7550 W portable generator. The engine is 4 years old and has run no more than 15 hrs. Unit was kept in garage for about 3 years, then moved to a covered lanai about a year and a half ago. The unit was not started for about 4 months. It would start, then shut down in under 10 seconds. Drained the gas tank and added 5 gal of fresh gas. Flushed the gas lines to the carb. Cleaned the carb. bowl. Checked and serviced both the foam and the paper filter. Checked oil. When I removed the oil filler plug, there was a free flow of oil indicating that it was at the proper level. The carb has been flushed with a commercial cleaner. The engine starts easily, both by electric starter and the rope pull. Engine runs smoothly for about 10 seconds then shuts down. The low oil pressure light has never indicated that
oil pressure was a problem. What should I try next? This is too heavy a unit for me to transport to a repair shop. I want to try everything I can do before having a service person come to my location.

Hello, and thank you for choosing JustAnswer. I'll be assisting you today and am committed to providing clear and concise answers to your question.

 

For diagnostic purposes, please disconnect the wire to the low oil pressure switch and see if it runs longer than 10 seconds. Then shut it back off if it does. Please let me know and we'll continue...

Customer: replied 5 years ago.
It stopped in the same way

Quite odd. Does it restart right away?

 

And just to verify, this is the switch you removed the wire from, correct?

 

graphic

Customer: replied 5 years ago.

Usually the engine kicks over on one push on the starter. this time it took 2 attempts.

 

There are two (2) blade attachments on the switch. There is another wire to the low oil indicator light. I had removed only the WHITE wire from the switch. Was that enough to have disconnected the Low Oil shut off system?

 

 

The low oil switch should not have any wire attached to it for this test. The time frame you indicated matched exactly with the time delay built into the low oil shutdown portion of the control board, so that's why I was expecting it to run with the switch removed from the circuit. The switch is normally closed and when oil pressure builds, the switch will open.
Customer: replied 5 years ago.
I removed the other wire (Green Color). I cannot get the engine to start either manually or with the electric starter.
Are you sure you are not removing a wire other than just the one to the low oil switch? What's the model number of your 7550 and I'll try to post a schematic.
Customer: replied 5 years ago.
Model GH-410 13/15 HP Guardian OHVI Engine oil filter
I already have that information from your first post. What I need is the model number of your 7550 generator from the model identification tag.
Customer: replied 5 years ago.

Model # XXXXX

Thank you. There should be a yellow wire.

 

graphic

Customer: replied 5 years ago.
yes there is one yellow wire from the low oil pressure switch to the three 3 pin connector and another from the oil pressure switch a control location
So what were the results of the test?
Customer: replied 5 years ago.

Your 1:29 PM message read, "Thank you. There should have been a yellow wire." You also sent a wiring diagram. You did not ask me to test anything.

My first message was:

 

"Info Request 3/1/2011 at 12:24 PM (6 minutes and 57 seconds later)Hello, and thank you for choosing JustAnswer. I'll be assisting you today and am committed to providing clear and concise answers to your question.

For diagnostic purposes, please disconnect the wire to the low oil pressure switch and see if it runs longer than 10 seconds. Then shut it back off if it does. Please let me know and we'll continue...

 

You mentioned removing a green wire and a white wire. So then...

 

Info Request 3/2/2011 at 9:38 AM (11 minutes and 40 seconds later)Are you sure you are not removing a wire other than just the one to the low oil switch? What's the model number of your 7550 and I'll try to post a schematic.

I'm still trying to get the answer to the original question. The information provided was to guide you to the correct wire

 

Customer: replied 5 years ago.
The only wires I removed were the green and white wires from the engine run switch. With those removed, I could not start the engine. I did not remove the YELLOW WIRE from the LOW OIL PRESSURE SWITCH. Do you want me to reattach the White and Green wires to the Engine Run Switch then disconnect the Yellow wire from the Low Oil Pressure switch to see if it will run beyond the twenty seconds??
Yes. The only wire I asked you to disconnect was the one to the low oil pressure switch. No other wire should be disconnected for this test.
Customer: replied 5 years ago.
A small AHA!!!! Disconnected the Yellow wires from the Low Oil Pressure Switch. Started the unit. It ran more than 20 seconds, and turned it off with the engine run switch. I suppose that it is with the low oil pressure system.
Customer: replied 5 years ago.
If you believe that the low pressure oil switch is the problem, what is the part number, and where can I get a replacement? Sorry about my understanding of switch.

Absolutely not a problem. We're here to help.

 

You have two possibilities, and the switch being faulty is usually the problem. However, it can also be that oil pressure is actually too low to operate the switch. The proper diagnostic is to either check the oil pressure, or to pressure test the switch to 10 psi and see if it works. However, again the odds are that the switch is simply faulty.

 

The switch is part number 099236 and can be ordered from any Briggs & Stratton Dealer or also from M&D online. Here's a link to that site and the part number.

 

http://www.m-and-d.com/GEN-099236.html

 

 

Hope this helps!

Customer: replied 5 years ago.
I may not be able to get back to the generator today to check the pressure. Is it possible that the LED circuit could be faulty? I will check the continuity as soon as I can. You certainly have earned your money, but I would like to wait until I check the pressure guage and the LED circuit before "ACCEPT ANSWER". I'll try to get to it later today.

The LED is simply a "light emitting diode" and serves only as a visual indicator by flashing during shutdown in a low situation. It has no functionality beyond that.

 

Keep me posted on your pressure testing please.

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