John Deere 180 Riding Lawn Mower has power loss after 25 minutes of use.

curtis63

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  • / John Deere 180 Riding Lawn Mower has power loss after 25 minutes of use.
I have a John Deere 180 riding lawn mower. I think its about 30 years old. Anyway, it started losing power after warming up. The symptom would be that it would get weaker and when the blades were spinning, it would start to die. I turn off the blades, it seems to have power again. It progressively got worse and worse to the point I could only mow for about 5-10 minutes and it would get weaker and weaker and putter out and even backfire until I turned off the blades. (There's an electric switch to engage the mower blades).

Anyway, I looked up the symptoms and many sites said it was the ignition coil. So, I replaced the Ignition Coil and even the carburetor. I had previously replaced the fuel pump, all fuel lines, and the fuel filter. It seemed to start working again. I was able to mow my lawn, which had grown about 8 inches tall. It mowed it without wimping out.

However, after about 25 minutes, it started wimping out.. I had to use the choke just to keep it going. Also, I had to turn off the blades every once in a while to get the motor back up to speed because it was just choking and unable to keep running.

Any ideas what ELSE the problem could be? Seems to be fine when I start it up, but starts losing power and dying after about 25 minutes of use.
 

bertsmobile1

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  • / John Deere 180 Riding Lawn Mower has power loss after 25 minutes of use.
If it responds to choke then you are not getting enough fuel or too much air.
With old mowers the most likely suspect is a blockage in the outlet from the tank.
No 2 on the hit list is a blocked fuel cap vent.
 

Rusty516

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  • / John Deere 180 Riding Lawn Mower has power loss after 25 minutes of use.
Does it do this with the blades off? Have you tried not engaging the blades? When you turn the blades off, does it seem to run like it should, or is it just making it easier for it to run with the blades off? Does the mower have an electrical PTO, or does it engage the blades with a mechanical lever?
 

curtis63

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  • / John Deere 180 Riding Lawn Mower has power loss after 25 minutes of use.
Does it do this with the blades off? Have you tried not engaging the blades? When you turn the blades off, does it seem to run like it should, or is it just making it easier for it to run with the blades off? Does the mower have an electrical PTO, or does it engage the blades with a mechanical lever?

It has an electrical PTO. The mower seems to bog down less with the blades not turning. This all acts up after the mower has been running for about 20-30 minutes. Initially, it was easily mowing through 12 inch tall grass without a burp, but after about 20 minutes, it started coughing and backfiring. When push in the clutch and turn off the blades, the engine regains power and then when I re-engage the blades and start moving again, it gradually gets weaker and putters again. Once it starts puttering, it's pretty much going to not work very well without a few hours to cool down again...
 

Rusty516

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  • / John Deere 180 Riding Lawn Mower has power loss after 25 minutes of use.
It almost sounds like something is getting tight in your mowing deck, and it gets to the point where its killing your engine's power. Does everything sound pretty smooth, and quite when the blades are engaged? I would see how easy it is to move the blades by hand before you start mowing. Then mow until this starts happening, kill the engine, and try moving the blades with your hand again, see if it feels the same
 

curtis63

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  • / John Deere 180 Riding Lawn Mower has power loss after 25 minutes of use.
If it responds to choke then you are not getting enough fuel or too much air.
With old mowers the most likely suspect is a blockage in the outlet from the tank.
No 2 on the hit list is a blocked fuel cap vent.

Well. The problem is finally solved. THANK YOU BERTSMOBILE1 !!! It was a blockage in the outlet from the tank as you suggested. Before I had checked that though, I had replaced the following on my mower:

Ignition Coil
Fuel Filter
Fuel Pump
All fuel hoses
Carburetor
Ignition Coil
Spark Plug

And with all of the above fixes, the problem still remained. However, I did end up fixing it.

The problem was the fuel valve that comes out of the gas tank. It has a 7 inch tube that is inside the fuel tank and reaches the bottom of the tank. Anyway, that tube was clogged completely up. I removed it all fairly easily. It just had a rubber bushing holding it in. Here's the process to fix the problem I had:

Remove the fuel hose connected to the gas tank shutoff valve
Pulled the valve and tube out of the gas tank.
Just wiggle it as you pull. No tools needed.
Take the valve apart. Just one nut holding the knob.
Attempt to blow air through all the tubes in the valve
No air could blow through, so use a thick wire like a coat hanger and clean the inside of the tube
I noticed a lot of build up and fibrous clogged material (probably 30 years worth of old decomposed grass clippings).
Remove all of that gunk out of the inside of all the metal tubing
Blow air through the tube to verify clog has been removed
Put it all back together
WHAM-O !!! The lawn mower roars to life

I think that the problem is finally solved. It all came to about 20 minutes with a hanger and some scraping out the goo from the inside of a 30 year old metal tube to make a hole for the gas to flow out of the gas tank into the fuel line.

All is right with the world!! Thanks for your help and suggestions everybody !!
 

bertsmobile1

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  • / John Deere 180 Riding Lawn Mower has power loss after 25 minutes of use.
Love to hear a happy ending.

Grass clippings are a big problem in a fuel tank.
because there is little to no oxygen in the fuel the clippings can not fully decompose so form those almost transparent semi floating fibres just waiting to form a plug.
Then when there is no flow to suck them into the hole they float off again pretending to be innocent.
 
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