Briggs engine won't stay running . . . At my wit's end! Help please.

Old 08-06-14, 03:26 PM
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Briggs engine won't stay running . . . At my wit's end! Help please.

I have a Murray Widebody LT with a 15 horse Briggs & Stratton (model 28N707). A friend borrowed the machine, and this is what I was told . . .

"I cranked it up and it was running fine. Then it suddenly backfired and shut off. I could not get it started after."

Spent a lot of time trying to get it to run to no avail. I now have been able to get it running for short periods, less than a couple of minutes at a time. However, it continues to "spit and sputter", backfiring through carb and exhaust.

First, I checked the flywheel key. it is fine.

Then I drained the carb bowl and fuel lines he said he had just put fuel in it. It initially began running fine after doing this. So after about 25-30 seconds of running I shut it off thinking it was just water in fuel and felt it was fixed.

Went back about 30 minutes later and back to the same issue. Spitting and sputtering out carb and exhaust. Although occasionally, it will run fine and then go back to spitting and sputtering.

What I did not do is drain all the fuel from the tank. So here is my question. Will bad fuel / water in fuel cause this issue or do I need to look deeper?

Someone help please. Thanks.
Old 08-06-14, 03:58 PM
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Drain all the fuel from the tank (and carb again) and replace it with new. It sounds like it's got water in it.
Old 08-06-14, 06:22 PM
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Water is heavier than gas, and when a small amount gets in a tank, it rolls around at the bottom and goes down the tank outlet a little at a time. Then, it pools up in the belly of a hanging fuel line, the bottom half of the fuel filter, and every low spot it can find. You drain the carb, run it a while, and after bouncing and turning a bit, more works its way to the carb.
Old 08-07-14, 04:55 AM
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I just bought a Poulan rider with the same engine having the same problems. ($100 gamble) After draining all the fuel and putting in new, cleaning the rusty flywheel and pick up, regapping it, the engine still spit back. I pulled the OHV cover and noted both valve rockers were excessively loose and rattled. Regapped them and it ran like a sewing machine.
Old 08-07-14, 02:15 PM
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It certainly would not hurt to check your valves as chandler has indicted. The valve lash clearance should be 0.003" to 0.005" on the intake and 0.005" to 0.007" on the exhaust. With the problem you are experiencing my concern would be no valve clearance at all or something has broken or come loose in there. Only 4 bolts and it may shed some useful light. Or it may very well just be water in the gas.

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