Poulan 2150 primer bulb working backwards!
Poulan 2150 chainsaw. All fuel lines are in their original position. Primer bulb is marked tank and carb side. Tank side is for larger line and runs into tank and fuel filter. Carb side is smaller diameter line and runs to carbs lower fitting. Top carb nipple with small line runs to tank vent and sticks about 1 inch into tank top. Pushing on primer bulb PUSHES air OUT of fuel filter and sucks from carb side of bulb. Pulled out primer bulb and verified action separately. Definitely pulls from carb side and pushes into tank side which makes no sense to me at all. Going backwards like that would require source of gas to be from vent line in tank which isn't low enough into tank and would not be filtered. Pressing on the bulb pressurizes the fuel tank. The fuel sprays out when you open the tank!! I can't believe primer bulb is suddenly working backwards. The saw just stopped working in the field and has not run since. Has anyone else had experience with this? Hope you can help. Thanks. If all fuel lines are in original position then they were wrong. The line with the filter should go to the carb, then from carb to suck side of primer and return to tank from the blow side of primer. Correct...they are not in the original position, it can't work that way. The port marked tank goes to the return line in the tank, not the supply line with the filter on it. Thanks for the responses! How do we explain that the Primer bulb is marked carb and tank. The Tank side line is larger than the carb side line! Cannot get them mixed up. The larger line when the bulb is pressed is blowing air into the tank and pressurizing the fuel tank. Is it possible that something in the primer bulb assembly has broken and some how reversed its function? If someone out there has one of these I sure would appreciate someone looking at it to confirm how it works. I know what you guys are saying is right about it not working the way I found it when I disassembled the saw. Yet you need to believe what I am telling you about what I have found. The saw just suddenly stopped working in the field and nothing has been disturbed of changed from the original configuration except it just started working backwards!! (No human intervention) Thanks for your help. Of course I will purchase a new primer assembly and I will let you know what I find out. All comments, observations, experiences and advice is greatly appreciated. Well why would you want to filter the return fuel line over the inlet? The return line is not meant to pressurize the fuel tank and the primer system is only meant to purge the air bubbles from the lines and carb. Of course I can't explain what you found but I don't believe it is correct. The line marked tank blows air out when you press the primer. That's the way it's made and how it is supposed to function. It connects to the line with no filter going to the tank. The suction side of the primer goes to the carb. This is all regardless of how big the primer fittings are. That doesn't indicate what lines go to it although it would seem that way. I have some to look at in the shop, but I don't need to look at one to verify how it is connected...I work on them for a living. That's the whole of it....there is no other way for it to work. I don't think it suddenly started working backwards, I just think you have the wrong impression of how it works and should work. The check valve in the primer is put into place in one direction, and it can't come out and turn around. It's not physically possible for multiple reasons. The only way the primer can function backwards is if someone reverses the lines on it. I'm looking at the primer pump from my poulan 2150 chainsaw right now and the larger fitting marked 'tank' is connected to the blue tube going to the carburetor. The smaller fitting marked 'carb' is connected to the clear tube going to the tank. There is a much smaller tube (vent?) which is not sealed going from the carb directly into the tank. I have pulled this tube out of the tank and the chainsaw continues to run fine so it may be a pressure relief for the tank. It appears to me that the pump is marked backwards. Go figure! If it helps,, These are NOT really primer bulbs... They just got a bad name along the way!!! They are really a fuel system purge bulb.... They will never give a squirt of fuel into the carb as most people are used to seeing on lawnmowers...All they are designed to do is to pull the air from the carb when you release the button,, push it into the tank when you push the button.. I've seen lots of people get mixed up because of the term Primer bulb... Hope this makes it clear helps some ??? Roger If you have a line running from the carb to the tank and it runs fine with it removed, something is wrong. The return line should go from the primer to the tank. The supply line should go directly to the carb. It sounds like your return line is connected to the carb? With it removed from the tank, you risk fire/explosion. No matter what the primer says, the fitting that blows out when you push it goes directly to the tank. The fitting that sucks in when you release the primer goes directly to the carb. The line with the filter on it goes to the carb inlet. Every time, no matter how it is marked. My Poulan 2150 chainsaw's primer/air purge bulb is marked 'Primer' on the side of the chainsaw. It is labeled an air purge assembly on the parts diagram. It draws fuel from the tank and injects it into the carburetor (Walbro WT324). I know, because I can easily flood it with the primer and I've watched the fuel spray into the carb throat whenever I press the bulb. The primer valve also blocks fuel from draining out of the fuel line back into the tank. There is a third line, approx. 1/16 ID which runs from a small black plastic fitting on the carb into a small hole in the fuel tank. The saw will run with this removed but fuel will splash/dribble out of the hole in the tank into the area under the carb, so it needs to be there to plug the hole. All I know is what I have observed on my particular saw. OK, my bad, after fooling around with my 2150 a little more I seem to have found my error. The person who owned this saw before me had swapped the primer source tube (unfiltered) with the normal run fuel tube (filtered). What I thought was a vent tube was actually the primer fuel source tube. What I thought was the primer fuel source was actually the normal run fuel line. I would prime the saw and it would run but not very well or for very long. I also have replaced the primer bulb as it was getting cracks and leaking air, which I thought was the reason for reduced runtime. Hope this helps someone else. Oh yeah, as noted by others on this thread, the primer draws air and/or fuel out of the fuel chamber (behind the diaphragm) which then draws fresh (filtered) fuel into the fuel chamber from the fuel tank. The unfiltered line just returns any air and/or fuel back to the tank. If you have the tank/carb lines hooked up backwards on the primer assy then you will pump unfiltered fuel into the carb. This may get you started but it can't be good practice. Besides drawing dirt into the carb it can cause flooding and much cussing. Thanks to everyone for their input. I learn something new almost every day! But usually only after lots of head scratching. Originally Posted by fretless52 OK, my bad, after fooling around with my 2150 a little more I seem to have found my error. The person who owned this saw before me had swapped the primer source tube (unfiltered) with the normal run fuel tube (filtered). What I thought was a vent tube was actually the primer fuel source tube. What I thought was the primer fuel source was actually the normal run fuel line. I would prime the saw and it would run but not very well or for very long. I also have replaced the primer bulb as it was getting cracks and leaking air, which I thought was the reason for reduced runtime. Hope this helps someone else. I am having the same problem. After replacing fuel lines the primer bulb was pushing air into the tank. I know I connected the lines the same as the were before the fuel line replacement because I did them one at a time. After reading your post, I reversed the lines on the primer and now the fuel is priming but the saw will only start and run for a second. Any help on how you solved your problem would be apprcieated. Thanks... Hello sg107, Are the lines connected as I described above? Originally Posted by cheese Hello sg107, Are the lines connected as I described above? Hi Cheese, yes. After replacing all the fuel lines and filter I found that when the primer blulb was pushed that air was comming through the filter and the lines were not purging. I then reversed the lines and now fuel is pulled from the filter and tank and sent to the carb with the overflow returning to the tank. Problem is now that when I start the saw, it will only run for a few second and will not draw fuel on its own. Thanks for the help, It looks as if you have the lines attached correctly as the bulb is actually a suction cup that will bring fuel from the tank and push it into the carb. Too much will flood it. Now as far as running a few seconds and stopping, it sounds as if one of the diaphragms in the carb may have a pin hole in them. The carb is a simple 3 section unit with the diaphragms sandwiched between. Once it fires, you are pulling the choke off, right? It is only needed for the first fire, then maybe half choke to keep it running until warmed. I'll check back in. Originally Posted by chandler It looks as if you have the lines attached correctly as the bulb is actually a suction cup that will bring fuel from the tank and push it into the carb. Too much will flood it. Now as far as running a few seconds and stopping, it sounds as if one of the diaphragms in the carb may have a pin hole in them. The carb is a simple 3 section unit with the diaphragms sandwiched between. Once it fires, you are pulling the choke off, right? It is only needed for the first fire, then maybe half choke to keep it running until warmed. I'll check back in. Thanks Chandler, will only start with half choke after a few pushes on the prime. Acting like it is not drawing fuel in after running. Just cleaned the vent on the cap but have not tried to start it. I know this is not an image of your chainsaw ( This actually from a weedwacker) but you fuel system is hooked up the same way as this one. I work on these on a daily bases and have to train other employees on hook them up and contrary to what a lot of people think you are not pushing fuel to carb you are actually pulling it through. Fuel filter should be on small dia fuel line going to carb from carb fuel line should go to short end of primer bulb,from primer bulb(the longer stem) should go back to tank. I find it strange but not unbelievable that you got one hooked up wrong from factory I have seen this once or twice before.If it is still under warranty I'd recommend tacking it back because you can cause damage to carb by priming it a lot when fuel lines are hooked up backwards. Hope this helps Thanks Ghost, The way I have it connected now is that when the bulb is pushed fuel flows through the carb and out an overflow to the tank. When released, the suction pulls fuel from the tank through the filter. When pushed, fuel will squirt into the carb so I can see how this could be a problem. Is this correct? Also, still having the problem of only running for a second after start. Thanks, Originally Posted by sg107 Thanks Ghost, The way I have it connected now is that when the bulb is pushed fuel flows through the carb and out an overflow to the tank. When released, the suction pulls fuel from the tank through the filter. When pushed, fuel will squirt into the carb so I can see how this could be a problem. Is this correct? Thanks, No As has been stated, when you push the primer, fuel/air should be pushed directly into the tank When the primer is released it should, fill the bulb by drawing/sucking, fuel/air directly from the carb. The line with the filter from the tank goes to the inlet of the carb. Originally Posted by BFHFixit No As has been stated, when you push the primer, fuel/air should be pushed directly into the tank When the primer is released it should, fill the bulb by drawing/sucking, fuel/air directly from the carb. The line with the filter from the tank goes to the inlet of the carb. I tried that and it would not draw fuel through the carb. If bulb is pressed with this config it just stays with as if there is something blocking it in the carb. This is with fuelline from tank to carb and from carb to primer bulb and then to tank. No fuel will prime. Thanks, BFHFixit is right.you may have problem in your carb if you have fuel lines on right. Originally Posted by gh0st BFHFixit is right.you may have problem in your carb if you have fuel lines on right. You have a restriction in the carb, lines or filter..... If it does not work with the lines connected as I/we have described, then there is another problem. Again... there is no other way to connect the lines and have it work properly. Got it running. Thanks for all of the help. Here is what I found: BFHfixit and Ghost were right. That is the only way it would run. What I found on my 2150 is that it is the top line from the carb if you are looking at the carb installed. Mine has a black plastic elbow. This is what I finally connected from the carb to the small side of the primer bulb. The large side of the primer bulb goes to the tank which is a small diameter hole. I used the small fuel line and heated the end around some needle nose pliers with a match and connected it to the large side of the primer bulb. Three pulls after a prime and she is running like a scared rabbit. There is no way that this thing was like this when I started but it is running now, so go figure. Thanks again for all of the help. BFHfixit and Ghost were right... Of course they were...Heck, they said it should be connected the same way I've been saying to connect it from the beginning. I don't understand how you figure I was wrong. Doesn't matter anyway, just wondering. Originally Posted by cheese BFHfixit and Ghost were right... Of course they were...Heck, they said it should be connected the same way I've been saying to connect it from the beginning. I don't understand how you figure I was wrong. Doesn't matter anyway, just wondering. Of course you were not wrong either cheese, neither was anyone else...I think Airman has hit on something with the red text hehehe New day, new attitude. I just re-read this and noted my negative attitude. Sorry if I came across badly. I just get frustrated when on this and other threads, folks ask connect their fuel lines, then decide to connect them differently, then post back asking why their equipment doesn't work with their fuel lines connected wrong. Then they finally connect them right and say so and so was right, they were connected wrong. It leaves me scratching my head. However, I do not do this for the recognition of being right or wrong, I do this to help people. I apologize for being thin skinned and letting a little thing bug me like that. I want to convey myself as approachable and friendly, not sour. Shame on me, but look out, I'm gonna do better on the next one! Cheese Hey cheese. I just had to register so I could weigh in on this topic. You did a great job on describing the way it works. I also had a fuel line problem with a chainsaw. Took it apart and found fuel lines deteriated so I didn't know the orginal route of the fuel lines. You guys helped me alot. I needed to know two things. 1) Identify the inlet/outlet of the Walbro (walbro.com) carb and 2) Learn that the primer sucks. You made item #2 very clear. THE PRIMER SUCKS AIR FROM THE CARB WHICH IN TURNS SUCKS GAS INTO THE CARB FROM THE FILTER LINE. online help is awesome....thanx to all on this forum. signing off, dbteeitup Glad you found what you needed here, and welcome to doityourself! Hi All, Wow, nice to see this thread is still going ! Like dbteeitup, I Also signed up to weigh in on how confusing it may be to put things together once they are apart..yet after reading this thread it made perfect sense (even if I read it 3x to make sure) lol Now to my problem, All lines are have been hooked up correctly. Lines and filter are new clear, but plunger gets stuck in (like its under a vaccum) after 2 presses ! Plunger seems fine works well outside of the unit..So Im guessing the carb is clogged ? I pulled the carb the gaskets/screen looked fine...nothing punctured or looking clogged. Pulled out a Mityvac pulled some vaccum on the carb outlet (suction) side everything seemed good.. How far can I tear down this carb before Im doing more harm than good, and what would/should I replace before buying a new one ? Thanks in advance. You may need to replace the diaphragm and gaskets. The screen should be removed and cleaned and then verify that the passage behind the screen is clear to the needle/seat area on the other side of the carb. This is where the fuel flows through the carb body when priming it. As has been stated, when you push the primer, fuel/air should be pushed directly into the tank When the primer is released it should, fill the bulb by drawing/sucking, fuel/air directly from the carb. The line with the filter from the tank goes to the inlet of the carb. newbie here... having a similar issue, but with complications... my Poulon chainsaw is nearly 10 years old, and i dont use it much. i bought it brand new and never had it serviced, so its never been opened up, till now. all my lawn machines are about the same age, and they all run terrible. what the universal problem seems to be is old, rotted fuel lines. i replaced them in my weed whacker and push mower, and they run great now. so naturally, i looked at them in my chainsaw. sure enough, the ones inside the tank, with the fuel filter on it, rotted completely, to the point where the line wasnt in the fuel anymore, and the filter was rolling around loose inside the tank. all the other lines are original. theyve turned hard and arnt as flexible as they used to be im sure, but they seem solid and good, so i dont think i need to replace them. the problem im having is, i dont know which line the fuel filter goes on. i read this thread, and the quote above in red, and it seems to explain the fuel flow fairly well, except i dont know which line on my carb is the carb inlet. and the original piping seems to differ from the above discription as well. i have a very short (original) line going from the bottom of the carb to the top carb' side of the primer bulb. an original long line going from the bottom 'tank bulb to the tank. inside the tank, that line has a fitting on it that (looks to me) like it should be where the fuel filter should go, by attaching a short hose jumper on it. i have another very skinny line (but still long, original) going from the top of the carb, directly into the tank. no fitting inside the tank on that line. when i push the primer bulb, all i get is a gurgling sound. it doesnt fill the bulb, and doesnt seem to draw any fuel from the tank, thru the carb. the way i have it now, i have the filter on the primer bulb tank line, with the smaller line (going directly to the top of the carb), unfiltered. is this correct? it doesnt seem so, reading the flow from above, but then, what is that fitting for, if not the filter? which line on the carb is the inlet? top or bottom? how can i tell? hope this makes sense, and is clear... hope you can help! thanx! The thin line going into the tank should be long enough to reach the bottom and lay there with the filter attached to it. The other end to the top of the carb. thats it! thats all i needed! moved the fuel filter to the small line and it runs like new again! thanx! geee... i feel like a pro now! -think ill go fix my friends chainsaw now! Great! Glad to help. ________________ If you push the primer bulb, and it creates a vacuum/collapses, you need to try swapping the lines on the carb. I say this bacause so many people say they put the fuel lines back the way they were. And they honestly believe they did, but it is easy to mess up. So if you have enough fuel line to swap them, then give it a try. some carbs are confusing on which is IN and OUT. Some carbs are mounted upside down compared to others. Following the instructions mentioned above you should get it working. Remember if two sizes if fuel line, small is fuel filter and fuel to the carb. Big is vent to the tank, or out. This applies to primer bulb on the carb, or stand alone primer bulb. If you have been running a unit that either has the fuel filter broken off the fuel line, or you have the lines backward and are sucking fuel through an un-filtered fuel line, then you have the potential to clog the screen filter in the carburetor. It sits opposite the needle. can be found on the side opposite the wagon wheel diaphragm. Sometimes, once cleaned and reinstalled, and you have pushed the primer bulb a lot, or actually have the unit running. You may have to remove the carb again to get trash that wasn't where you could see it the first time. Clean the filter again. Don't take anything for granted, or swear that you did it right when messing with fuel lines or carbs. Usually the problem is looking you in the face, but your mind (what you think you know) won't let you see it. Good luck. Since the introduction of Ethanol in gas, we have seen a drastic increase in repairs on 2 cycle motors. Fuel lines and diaphragms can't handle Ethanol. it will dry them out quick. I even saw one Poulan saw that was bought a year earlier and never taken out of the box. When the owner finally tried to use the saw the fuel lines were brittle, you could not touch them without them crumbling. Remember, they run them at the factory. Heat doesn't help either. If you aren't gonna use it empty the fuel out, prime it, empty it, and try to start it several times. That may help you preserve your lines and carb. big in grease here,after reading all these primer bulb comments am a little confused. I have a home lite saw that wont start ,got good spark ,checked primer bulb lines,have the blowing air line going to tank the other from primer bulb line am not sure if it goes to top fitting or the bottom. Thanks in advance for any suggestions. It is a Ranger 33cc with a walbro WT433 carb. Look at how the carb is put together. One side has a cover with one screw holding it on, the other side has 4 screws holding the cover on. The fitting near the side with one screw holding the cover on is the fitting that goes directly to the tank line with the filter on it. The other fitting goes to the suction side of the primer.
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