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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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On Sat, 02 Jul 2005 23:49:44 GMT, "James Sweet"
wrote: "spongehead" wrote in message oups.com... I got the needle at a local repair guy for 2 bucks. Came with needle, clip and some liitle white gasket looking thing. The white thing didnt quite fit anywhere so I left it out. Put everything together and it started right up but didnt last long. I have to keep pushing the bulb to keep it going. Is it because of the little white thing or am I losing air somewhere? Is this an engine with a float bowl carb? If so, remove the banjo bolt that holds the bowl on and clean out the tiny passages in it, those clog easily. The little white o-ring is the needle seal. It goes up in the needle well. If you look up in the needle well wth a flashlight you'll see the old seal.(It'll be stained a yellow-brown color from the gas.) Yo can pry it out with a small right angle dental pick or a slotted jeweler's screwdriver. alternately you can also get it out by shooting compressed air through the fuel supply inlet, should pop right out. Press the new seal in using a dowel or punch the same diameter as the seal. A bit of fine machine oil can be used to lubricate it to make it slide in easier.. Be sure it seats firmly in place. Test the needle to seat action before reassembling the carb to avoid flooding out the mower. You say it didn't last long. Did it just quit after running for awhile or did it try to start and then die out? The next thing that could be a problem is the primer bulb. Depending on the model it could either of three different type priner bulbs.(The carbuerator draws part of the suction required to pull gas from the bowl through the primer bulb ports. If the bulb is rotten or has a puncture it'll cause suction loss.) A visual inspection on the bulb will usually tell. It'll be cracked or split or be "gummy" when you squeeze it. It's easy to replace and doesn't cost but 3-4 bucks.(Sears or parts store.) It'll be either the round non vented bulb, black, red or orange in color or the accordian style that comes in either non-vented or vented.( will have a small 1-2mm hole in the center of the bulb.) All are held in by a circular spring clip. It has 5 or so square tabs that stick out to grab the primer bulb well walls. It can be prized out using a small slotted blade screwdriver, either a #0 ot a narrow slot #1 blade.(jeweler's driver will work as well.) Spray the whole spring and housing with a bit spray oil to slick it up a bit. Prize under one of the tabs until it moves out a bit then mover onto the next one going a bit at a time in a circular pattern until you get it out completely. The bulb can then be pulled or prized out. don't worry about damaging it, it's a toss off item and can't be fixed. Clean out the well with a bit of carb cleaner spray and a stiff bristle brush, wire bruch is fine. You can also scrape out the old rubber with a screwdriver or dental pick. To install the new bulb just place the bulb all the way in and press in the new retainer clip with a small slotted screwdriver. This is done by placing the tip of the screwdriver into the circular depression in the ring and pressing a gently at different points of the ring in a circular pattern untill the ring is all the way against the lip of the primer bulb. Then gently but firmly press with the screwdriver in the depression of the ring at the base of each of the retaining tabs. You can test for a firm seat and lock by simply pinching the tip of the primer bulb between forefinger and thumb and giving it a gentle tug. If it pulls out the tabs on the retaining ring have been overstressed and need to be bent out straight.(Sometimes they come from the factory out of spec and won't form a tight fit on your particular carb housing.) If the original ring came out in one piece and didn't snap you canuse that one. However to retension a spring, new or old, you use a pair of needle nose pliers and gently bend the tabs out a bit so that they'll fit snugly down the bullb well on your carb. Just be careful as it is easy to snap the ring itself overstressing the tabs. Also ensure that all of the fine ports on the carb are clean. This includes the small hole on the lower side of the primary jet well.(The well that the brass jet/bowl screw screws into.) Also the brass bowl retaining screw depending on the model also has one or two small ports on it that need to be clean for fuel to get to the main supply port. The short screw has one, the taller screws have two, 180 degrees opposed at the base of the screw.(just under the hex head.) You can use an aerosol carb spray to clean them out. I use either the High-Tech brand from Wal-Mart, The store brand from Autozone or a good name brand like Justice Brothers Carb spray. Anything that is acetone base is good. Avoid Gumout carb spray, worst stuff made. Most all come with a red plastic pipette for blasting out fine ports, use it. If the clog is stubborn spray some cleaner in a small cup and soak the parts to soften the clog up.(I use the plastic cap that comes on the spray can.) If the ports won't unclog using the cleaner take a small piece of stiff wire.( I use a piece of copper strand from a piece stranded automotive wiring 18 gauge or whatever.) Gently push it through the clogged port to break up the tarred gunk, follow with a healthy spray of cleaner. Use the pipette and carb spray to back blow the ports in the main intake of the carb also. This'll clean out the primary suction port that runs through the welsh plug and the seconday that runs through the primer bulb housing. Let parts dry or blow off with compressed air, then reassemble carb. |
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