Trouble with 18 HP Briggs and Stratton

My 18 hp B&S on my Garden Tractor won't continue to run. It is about 10 years old. I mowed the grass a few weeks ago and it ran fine until I was almost done with the 1 acre mow job. It started to lose power as I was climbing a small hill in the yard, then it died. I was able to restart it, but I had to close the choke fully in order for it to stay running, and the it only ran for a short distance before it shut off again. This week, I could not get it to stay running for more than a few hundred feet before it shuts off like it no longer got gas or the key was shut off.
What I did: Pulled the fuel filter off and blew through it from both ends. No obstructions, and I could see the screen was clean inside. I blew through the gas line that goes to the gas tank and was able to blow bubbles in the tank. I replaced the fuel filter with a piece of tubing, just in case it was the filter. I removed the gas line from the carburetor and the gas ran out freely. I pulled the cover off the carburetor and checked the diaphragms. No holes, tears or problems. I ran it with the air cleaner off and the in-line fuel filter removed. No difference. The gas is not old and the tractor is used year round for lawn mowing and snow blowing.
As far as I can figure, it runs out of gas or perhaps heats up to where it seizes up. Is there an oil pump that may have gone bad?
--
Bill

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My older 18 hp B&S twin has a fuel pump on the back side (nearest the steering wheel). It caused a similar problem a couple years ago. Also kinda difficult to get at. All I had to do was take it apart and clean it.

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On 6/20/2005 12:57 PM US(ET), Srgnt Billko took fingers to keys, and typed the following:

Thanks, but no fuel pump. It is gravity fed. The gas line runs from the tank directly to the carburetor.

--
Bill

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willshak wrote:

I'll bet the diapragm has lost its flexibility and the accelerator pump isn't working any longer. (You ran it dry last Fall, right?). Just by a rebuilding kit and replace the diaphragm. Don't bother with changing the jets and other small pieces because you'll screw it up.
While you're at it, check that the carburetor floats don't have a hole in them. And, check the needle valve by blowing into the fuel inlet and gently moving the floats up and down. Sometimes dirt gets into the needle valve and it can't shut off, flooding the engine.
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On 6/20/2005 1:03 PM US(ET), Stubby took fingers to keys, and typed the following:

I will assume it is the carburetor. I changed the basic red plastic in-line filter to a clear type and tried to start it. No fuel entered the filter. I will get a carburetor rebuild kit tomorrow. This tractor is never run dry. It serves year round as a mower and a snow removal vehicle with a front mounted snow blower.

This carburetor does not have a float tank.
--
Bill

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Stay away from those JD tractors!

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Stay away from those "Stanley" tractors. You do know they make them don't you ?
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On 6/26/2005 9:31 PM US(ET), Stanley took fingers to keys, and typed the following:

My 10 year old Murray built, Agway branded tractor hasn't been anywhere near a JD tractor, so that's not it..

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Bill

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I assume that it is a twin 18. A real common issue on these are the armatures (ignition coils) Customers a lot of the time state that the choke helps keep them going. It isn't always a matter that they loose there spark. Infact, the coil has a built in capacitor that times the spark and they come out of time. Usually they start out as a hot running condition and get worse. The partis about $50 and all B&S opposed twins use the same one.
BTW the diaphrams in the front of the carb are part of the carbs fuel pump. (Even if the tractor has a under hood fuel tank). It is also very easy to drop one of the 2 little springs upon disassembly.
Best of luck!

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On 7/7/2005 12:31 PM US(ET), encat took fingers to keys, and typed the following:

I had given up on trying to get it to run, so I called a local mower repair service that was about a mile away. I told him that I would drop it off. I then discovered that it wouldn't fit in my Nissan pickup with the mower attached, and taking off the mower and putting it on once a year was enough for me and is something I don't look forward to, so I called him back. He came and picked it up just before noon and then returned it that afternoon. He said there was nothing wrong with the fuel pump and all they did was to clean and adjust the carburetor ( I had sprayed carb cleaner into it myself, but it didn't help). He charged me $70.36 including tax. It would have been only $25 plus tax, had I been able to deliver and pick up the tractor myself. It has been running fine since then. Thanks anyway.

--
Bill

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