Engine Sputters & Dies


Old 05-28-02, 02:34 PM
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Craftsman Sputters and Dies...

I own a Craftsman Model No. 917.388390 push lawnmower with a 6.0hp B&S engine. I had to put the mower in storage for almost a year and it wouldn’t function when I tried to use it for the first time this year.

When I attempted to prime the mower with the priming bulb, it immediately filled with fuel. The mower would start, but it would immediately flood and shut down, pouring fuel out of the primer bulb. I took off the air cleaner base and found that the air cleaner gasket was ripped. I replaced the gasket. I also figured that the float bulb was stuck, so I removed the float bowl and ensured that it was free.

After I put the carb back together, I attempted to prime once again. This time, no fuel would come thru, so I figured that there was a block in the main jet. I disassembled again, found and cleaned the obstruction. I also ensured that there was no other residue inside the float bowl.

I re-assembled the carb and tried again. This time, when I primed the mower it pumped fuel properly. The mower started on the first pull, but shut down as soon as it had burned up the fuel that was in the chamber. The mower will continue to run if I continue to use the primer bulb, but it will not pump fuel by itself.

I have replaced the spark plug and the air filter. I am stuck, and I don’t know what to try next. Any suggestions?
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Old 05-28-02, 07:55 PM
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Hello and Welcome R_Cord to our Do-It-Yourself Web Site and our Small Engine forum.

Based on the information provided, the carb fuel ports and passages are still plugged up.

Remove and disasseble the carb again and look for tiny holes in the center brass screw. Possibly 2 holes in the pot metal center extension that the screw threads into.

Also clear the center extension orifice and any other ports in this location. Use the plastic extension tube provided with a can of automotive carb cleaner. Place the plastic tube into or up against any other port {Hole} and allow the pressurized canned cleaner fluid to clear the ports.

Use EYE PROTECTION during this proceedure.

Also check and insure the needles seat is correctly installed in the fuel entry port and the needle is correctly installed on the float. The float must be level to the carb body when the carb body is inverted upside down.

Check the float and be sure it does not have fuel inside it. If it does, it has a hole in it and it must be replaced.

Most likely I have not covered all of the potential problems. The other resident small engine service and repair professionals may offer additional suggestions, advice & help. Check back several times for additional replies.

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Old 06-02-02, 07:25 AM
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I stripped the carb down again and sprayed carb cleaner through all of the fuel ports to ensure that they are clear.

I reassembled the carb and primed. Again, fuel pumped into the carb chamber. I pulled the starter cord and it fired up immediately...and then died again.

Like before, the mower will continue to run as long as I continue to hit the primer bulb.

Why would the primer bulb be able to pull fuel up but the mower is unable to do so after it is running?
Old 06-02-02, 08:15 AM
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Hi, you might want to try a gas treatment. The particular brand I have used in the past is called "Gumout Small Engine Off Season Gas Treatment."

My mower did the same thing. Leaving it in storage can cause condensation to form in the gas tank=water in the fuel. The gas treatment helps to correct that. In addition, make sure that you have a clean air filter and a good spark plug.

I hope this helps!

Old 06-02-02, 09:23 AM
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Hello: R_Cord

If the fuel bowl had fuel in it when you removed it, at least we can determine there was fuel in it. Which means the float lowered and allowed the needle to unseat from the seat and fuel to enter.

If there wasn't fuel in the fuel bowl or not enough, it could be the fuel level is too low. Check to insure the float does lower the needle. Also verify that the float raises and fully closes the needle into the seat and no fuel flows.

To check the above two possibilities the quick way is to attach a fuel line to the fuel inlet while the fuel bowl is removed. Apply a tiny amount of air pressure by mouth to one side of the attached fuel hose. Raise and lower the float slowly.

Air should flow while the float is lowered but not when it is hand raised. Apply only a slight pressure on the float while it is in the up position. The results of this test may disclose the problem.

Another possibility could be a plugged air vent in the carb. Air must enter to allow fuel to flow. There is an air vent hole either high up on the side of the carb body or on the top of the carb body. It must be clear to function.

The primer bulb does not rely on any fuel flow operating system. Whether the fuel flow system may be gravity flow, a diaphram pump or venturi vaccum. The bulbs own system draws & pumps fuel by your depressing actions.

Which may also mean the fuel tank or fuel flow system from the tank is restricted enough to restrict fuel flow by any other means. In this case, test the fuel flow system by removing the fuel line at the carb and allow fuel to flow out for several minutes.

The fuel should flow freely for several minutes without any slowdowns or stopping. If it does not, there could be a restriction somewhere in the fuel delivery system or a plugged fuel tank vent cap. If fuel does flow freely for several minutes, all is fine.

Once again, if you need further assistance, use the REPLY button to add any additional information, etc. Recheck for additional replies often. My forum has several other professionals to assist you.
Old 06-02-02, 09:49 PM
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For such a simple carburetor, these things can give a lot of grief. I think you still have a restriction in the carb. OR...take the carb off, remove the bowl, look into the metal tube that the bowl screw goes into. There should be a plastic tube in there. You can screw a wood screw into it just enough to get a grip on it, and pull it out. Replace the 2 small "o" rings on it. Make sure all the old pieces of the old o-ring are cleaned out of the carb before installing the tube.

You did clean the tiny holes in the bowl screw, right? There are 3 on the sides of the screw...2 that are about halfway up the length of the screw, and one very tiny one near the top of the screw, and then one down in the center cup of the screw. (4 altogether). If one of these is stopped, it will cause this problem you describe.
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