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Donald
Donald, Small Engine Technician
Category: Small Engine
Satisfied Customers: 2025
Experience:  I have 25+ years of experience repairing 2 & 4 cycle engines
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I check the starter solenoid and it is sending 12.7 volts to

Customer Question

I check the starter solenoid and it is sending 12.7 volts to my murray 17.5 hp riding lawnmower starter when the starter is disconnected, when I connect the starter it only is sending about 6 volts. I just replaced the starter, the same thing was happening on the previous starter I had on the mower
Submitted: 10 months ago.
Category: Small Engine
Expert:  Donald replied 10 months ago.

Hello. Thank you for choosing Just Answer. My name is***** will be happy to assist you.

Expert:  Donald replied 10 months ago.

Can you get the model numbers from under your mower seat for me? I would like to pull up a wiring schematic.

Customer: replied 10 months ago.
Murray 42571X8A
Expert:  Donald replied 10 months ago.

Thanks. Can you give me a minute or two, to pull up a diagram of your mower?

Expert:  Donald replied 10 months ago.

Thank you for waiting. How old is your battery.

Customer: replied 10 months ago.
Brand new, FYI - the starter motor turns, but not fast enough to start the engine.
Expert:  Donald replied 10 months ago.

Thanks for this information. Are you familiar with using a screwdriver to jump across your solenoid post?

Customer: replied 10 months ago.
should I try this?
Expert:  Donald replied 10 months ago.

Yes, try this and let me know if you get the same results.

Customer: replied 10 months ago.
I got the same result
Expert:  Donald replied 10 months ago.

Thank you for checking. We need to determine if you have a bad ground. Do you have some jumper cables?

Customer: replied 10 months ago.
Expert:  Donald replied 10 months ago.

Use your black cable to go from the negative post on your battery, to a good location on your engine, then try starting your engine again.

Customer: replied 10 months ago.
Same results
Expert:  Donald replied 10 months ago.

This leads me to believe that your new battery is at fault. Battery voltage should never drop below 8.5 volts during start up. Dropping to 6 volts is much too low of a drop. Do you have another mower with a battery?

Customer: replied 10 months ago.
I bought the new battery because the old one was doing the same thing as the new one. This mower has never started very well with just the battery, I normally have to put jumper cables from the car to the mower battery to get it started, so when I connected to the car it would start pretty easily. This method has worked well for a while, until the last time I tried and now the starter motor will not turn fast enough to start the engine. For this reason I do not think it is the battery, both the old and new read 12.5 volts or above, but both produce the same results. Any other ideas on possible problems with the mower or do you think both the old and new batteries could both be bad?
Expert:  Donald replied 10 months ago.

Is your engine a Briggs and Stratton OHV engine?

Expert:  Donald replied 10 months ago.

If so, I would like for you to try something for me.

Customer: replied 10 months ago.
FYI- I put jumper cable from car to mower battery, while trying to start the mower, the volt on battery was about 10 volts and 6-7v at the starter
Expert:  Donald replied 10 months ago.

Remove your spark plug from your engine, then turn your key to start position. Let's see if your engine spins faster.

Expert:  Donald replied 10 months ago.

Have you check a your connections for tightness and cleanliness?

Customer: replied 10 months ago.
I will do what you say above, but first wanted to let you know I see some burnt melted plastic wire cover on the negative wire (black) near where it connects to the battery and the black wire seems to be getting pretty hot when I try to start?Should I remove both spark plugs or just one?
Expert:  Donald replied 10 months ago.

Both plugs. The wire getting hot, could be caused by a bad ground cable, or wire.

Expert:  Donald replied 10 months ago.

Is your engine a Flat Head or OHV?

Customer: replied 10 months ago.
With both plugs out, it does spin a lot fasterI there a way to bypass everything and take 12volts right to the starter, I just want to get it started so I can mow my 1ft grass
Customer: replied 10 months ago.
I believe it is a OHV there are two spark plugs one on right side and one on left. How can you tell for sure if it is OHV?
Expert:  Donald replied 10 months ago.

I believe that your best solution will be to remove your large black cable from your frame, and use a wire brush or sandpaper to clean your surface really good, to ensure a good ground. Clean your cable with a flat file.

Expert:  Donald replied 10 months ago.

If your mower is an older mower, you likely have a flat head engine. If your engine have overhead valves, your valve covers would have OHV stamped into them.

Customer: replied 10 months ago.
I do not see any OHV, so must be a flat engine. I will clean the wires with wire brush/file and get back to you will results.
Can you take 12volt directly to starter to start the engine?
Customer: replied 10 months ago.
What do you learn by the engine rotating faster with the plugs out?
Expert:  Donald replied 10 months ago.

If you have some jumper cables, you can go directly from a vehicle battery, to your starter. Do not start the engine on your vehicle, when doing this.

Expert:  Donald replied 10 months ago.

If your engine spin faster without your spark plugs inserted, this could mean that either your starter, your battery, or a bad connection could be at fault.

Expert:  Donald replied 10 months ago.

This also tells me that a belt or other attachment is not restricting your engine rotation.

Customer: replied 10 months ago.
Thanks so much, you have been a great help. Will check the connections tomorrow, hopefully. Well worth the $27.
Expert:  Donald replied 10 months ago.

You are very welcome! I will work with you until our problem is resolved. Wait until we are finished, before you rate my answer. There will not be any additional charges if we continue tomorrow, or if you need to ask follow-up questions to this question.

Expert:  Donald replied 10 months ago.

Take your time, and get all of your connections really clean, especially your ground connections.