Briggs & Stratton Help...backfiring and won't start
asand211
12 years ago
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mownie
12 years agoRelated Discussions
12.5 Briggs and Stratton won't start
Comments (2)It was tipped to untangle something it ran over. It is a Yard Machine 38" rider. For whatever reason the battery is dead. I didn't think the mower used the battery for anything but starting. I may have left it in the "on" position. So I jumped it and it was turning over. I changed the spark plug and sprayed carb cleaner in the intake. It started and ran for a while. I figured I'd leave good enough alone and I'll see if it starts again tomorrow. If so I'm going to buy another battery....See MoreBriggs & Stratton 18HP Twin I/C won't start
Comments (3)You did install the new coil correctly, spark plug leads come out towards back of engine then turn 180 degrees, come under the coil and out the Intake Manifold side of engine. Check for bad place in "Kill" wire insulation where it exits the cooling shroud. Walt Conner...See MoreBriggs & Stratton Getting Spark & Fuel - Won't Start
Comments (6)OK, I see in the IPL that item # 238 (Briggs # 691843) is the cap you referred to. Thank you for outlining the part about "holds 80 psi". Now that you have confirmed what I thought you meant, I need to ask, is 80 psi, the pressure you are applying to the cylinder (I presume you have an adapter air fitting threaded into the spark plug hole) with an air compressor, or is the compressor SET AT A HIGHER psi........and 80psi, is all the cylinder will maintain? I hope you understand what I am asking but let me put it another way. While you have the source of compressed air connected to the cylinder, does the air compressor cycle on and off to rebuild air that is leaking off "somewhere"? If the air compressor DOES cycle on and off, but you don't have any air leaks in your compressor air hose or plumbing, then the air must be leaking out of the cylinder somewhere. An "air leakdown test" is not simply to connect air to the cylinder and see how much pressure the connected air compressor is capable of maintaining (on the gauge). An air leakdown test must really be done with a gauge that "measures the PERCENTAGE of leakdown, even a "good cylinder" has "some leakage". It is neccessary to determine if the "actual leakage" exceeds the "allowable volume (%) of leakage" An air leakdown test is also conducted to determine WHERE the air is leaking from (valves? piston or rings? head gasket?). So, your answers to the questions of just how you are achieving the "80 psi for 30 minutes" will allow us to get past that issue as you may well be getting a false indication of "health" from what you have been doing there with the air pressure. During an air leakdown test, you should be listening to for air escaping into the exhaust system, or the intake manifold, or into the crankcase. Of course, the crankshaft must be stopped at the correct position AND HELD there so it cannot turn when the air pressure is applied to the cylinder. To "listen" for escaping air, I use a 2 foot length of plastic tubing (5/16" or 3/8" diameter, at auto parts store or plumbing supply). Place one end of the tubing into the muffler or exhaust port (if muffler is removed) and hold the other end close to your best ear. Any air leaking past the exhaust valve will be heard through the tubing. To check intake valve, place one end of tubing into the carb throat (with throttle wide open) or intake port (if carb is removed). Air escaping past the intake valve will be heard through the tubing. To check for air escaping into the crankcase (because of piston, rings, or head gasket defects), take the oil level dipstick out and listen for escaping air coming from the dipstick tube, or you can hold a small "flap" of tissue paper over the open dipstick hole, if significant air is coming out of the dipstick hole, it will lift the tissue off the hole. Wipe off the dipstick hole before laying the tissue in place so it won't just "stick" to any oil. OH YEAH, please post here and ask Mr. Walt Conner to post his "cryptic" e-mail address so you can contact him for HIS instructions on adjusting the valves. Walt is one of the primary Briggs contributors on this forum and most times Walt's instructions are better than Brigg's. It would not be "proper" for me to "set you up" with his e-mail as Walt has his own way of handling that. However, if you search in this forum and find a post where Walt "furnished" his e-mail address to another member, I'm sure he would be OK with that. It's just polite and PC to "ask first". Here is a link that might be useful: 313777 IPL...See More12HP Briggs & Stratton carb mounting bolts won't stay put
Comments (21)That might be true, on the vibration. This engine is 24 years old lol; it's still running strong when I can keep everything firmly connected. I HAVE had issues with the engine mount bolts coming loose and have to tighten them up regularly. Discovered when we inherited the tractor from hubby's grandma that the engine was being held to the frame with only three of four bolts, and those just regular bolts, not the OEM engine bolts, if it makes any difference. Got four OEM B&S engine bolts on eBay, and the lock washer that was supposed to go on one of them, but that one somehow came loose and fell out someplace. So back to a regular bolt in that hole. But I periodically tighten those bolts because they do seem to work loose; there is definitely some vibration going on but don't know if it's related to the PTO or not. No problems engaging or disengaging; no unusual vibration. So probably a good case for the carb bolts working loose; once they loosened (before I discovered the problem with them and the engine mount bolts) maybe they started wearing on the bolt hole threads??? Anyway, back to current problem. The bottom screw on the carb mount still can be tightened I think, but the muffler shield on top of the muffler directly below the carb is in the way making it REALLY difficult to access or pull the bolt; you can barely work a screwdriver in there to turn it and you have to bend the back edge of the shield down to do that. I think I need to use Locktite on both bolts though. I tried re-doing the Locktite on the top bolt and tightening the bottom one, and it held for all of about 5-10 minutes of running. After that I ended up bungee-cording the air cleaner to the engine to hold it against the engine block just to finish mowing, but by the time I was done both bolts were loose again. The carb mounts to the left side of the engine, btw. I can link you to a diagram if you like. (see below) I used the same tube of locktite I had from three years ago (still pretty liquid) but maybe it was no good? It was the removable type of Locktite and I am wondering if I should try something with a little more hold? Would JB Weld be better? I noticed it did grip the bolt in the hole better once it began to set but was afraid to tighten it down too much; just turned it till it felt like it was catching a bit and then let it set. Otherwise the bolt would just spin in the hole. I have gotten some more OEM bolts to try new ones but they are shorter than the bolt I used last; last time I just used an ordinary bolt that was a little longer than the original, and it did the trick, but this time I used the same longer bolt and it let go, after applying Locktite, tightening as best I could, and letting it cure 24 hrs before running. Should I replace the carb mount gasket again too? Seems to be ok but I haven't pulled it; I replaced it last go-around. The mower starts and runs just fine if I can just keep the darn carb on the engine! Here is the link showing the carb and air cleaner assembly for my B&S engine, no. 280707-0411-02. If you look at the carb bottom left, you can see the attachment point (intake??) you can also see the bracket I was referring to (no. 662 in the chart). Just a strip of metal that attaches to the little box with the choke linkage on it. Doesn't really support the carb-to-engine connection; the whole unit including aircleaner and bracket moves, I think. It's screwed down pretty tightly regardless. Carb and aircleaner assembly B & S 280707-0411-02 Thanks for any suggestions or advice!...See Morercbe
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