Starts, Runs, Stalls & Dies


Old 03-23-02, 03:31 PM
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B&S Engine Starts, runs, then stops

I have an MTD 22" mower with a 5HP Briggs & Stratton engine. I have used for several years. Recently when I push the starter plunger 5-6 times it starts ,runs, and then quits!

I have cleaned the air cleaner and even tried to run it without the air cleaner on but the same thing happens.

It has no adjustment screws.

I have started it this way countless times but it always stops when it runs out of the gas that was injected.

If I get to the plunger quickly enough after I get it started it will run if I keep pressing the plunger. At first If I kept pressing it for a minute or two the engine would then run on its own. Now it won't.
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Old 03-23-02, 04:34 PM
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boompa,,, Could you list the Modle Type and code numbers for your briggs,, Their found on the shroud,, We (i) could be better help if we knew which Carb we was dealing with. Sounds like a main jet plugged up to me but to be precice i would need the numbers

Old 03-23-02, 07:12 PM
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I have two simlar models this is a newer model. My older model has an adjusting screw on the carberator.

Model Type Code
128802-0627-01 96012958

Thanks for your help <><
Old 03-23-02, 08:11 PM
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Hello and Welcome Boompa to our Do-It-Yourself Web Site and our Small Engine forum.

Based upon the engine symptoms you posted, the most likely cause is a gummed up carb. Other possibilities could be a fuel restriction in the fuel delivery system, a plugged vent hole in the fuel cap or the vent hole in the carb body is plugged up.

Try this test first:
Remove the fuel tanks gas cap and try running the engine again. If the engine runs continuously, the vent hole in the fuel cap is plugged. If this is the case, carefully remove the cork inside the cap, clear the tiny hole but DO NOT enlarge it.

If that's not the problem and the engine still fails to run with the fuel cap off the tank, check the fuel delivery supply. Remove the fuel hose from the carb.

The fuel should flow out continuously with the cap off the tank. If fuel does not run out of the fuel hose with the cap off the tank, there is a fuel restriction in the supply. Clear the fuel restriction.

The fuel restriction could be a restriction from inside the tank or in the fuel hose. A plugged fuel filter in the fuel hose or inside the tank. Some engines may have a fuel shut off valve, if equipped with one.

The carb body also has a tiny vent hole some where on it. Locate the hole near the top or on the top of the carb and clear it but DO NOT enlarge it. Use a tiny pin if needed or a very thin piece of wire, etc. Wire from a pipe cleaner works as well as a piece of wire from a common wire brush.

If all the above fail to disclose the problem, carefully remove the carb. Note where and how the links and rods are attached to the carb b-4 you actually begin to remove it!

The other resident small engine service and repair professionals and moderators in this forum may offer alternate advice, suggestions, opinions and or test and repair methods.

Check back several times for additional replies.

Regards and Good Luck, Small Engine Forum Moderator
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Old 03-23-02, 10:18 PM
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I disagree guys, sounds to me like a shot diaphram. The carbs not getting fuel after the initial prime.
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Hello & Welcome: Dan

Excellent point. Thanks for mentioning it. You could be very correct with your diagnosis. The diaphram could very well be wornout, gummed up and or defective.

However, the type of carb has not yet been confirmed. Some engines use float bowl carbs that also have primers. Therefore, until the actual carb type is known, any carb or fuel related problem or condition could be the cause.

Last edited by Sharp Advice; 03-24-02 at 04:16 AM.
Old 03-24-02, 10:22 PM
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The engine Boompa has is a 5.5hp quantum engine with a float and bowl style carb, as determined by the engine model number. No diaphragm on this one, but good thinking Dan.
Old 03-25-02, 05:32 PM
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Thanks for the info guys. I didn't get around to attempting to fix it Sunday. I will let y'all know what I find.

About the gas cap...
The one that is on the mower is plastic. I don't recall any vent holes in it..

Any more suggestions would be more than welcome. I want to look at all the angles once I start to look at it.

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