Have I reversed the fuel lines on my purge bulb?

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Softdraw

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I replaced the purge bulb on a poulan pro pr5020. The saw sat unused for a while and the bulb cracked. Prior to that, the saw ran great. After I replaced the bulb, I can start the saw easily but it stalls almost immediately as the gas I choked into the carb burns. choking the saw to start is like giving the engine a shot of gasoline. After it starts, the saw quits. Could this be because I reversed the fuel lines? I can draw gas into the carb to start but I can’t get any fuel from the tank to the cylinder after that. Is this a bulb /fuel line issue or something else?
 

sawfan123

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If the bulb fills, and you don’t have the tank completely filled, they most likely are hooked up right.
If the saws been sitting that long that the bulb rotted, the saw needs carb work.
 

sand sock

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Bypass the bulb with a chunk of line and see if the saw runs. It could be the diaphram.

I just played the game of replacing parts on a leaf blower. Primer bulge pump, fuel lines, air filter. I brought it in to get the carb adjusted. My guys like how much do you want to spend. Its a min service charge of 100 a hour. Min1 hour plus the carb of $42
. nobody changes the diapram just change the carb. A new leaf blower is 180. I ended up buying a new carb and dropping it in. With the limiters on everything. You can do it.
 

Softdraw

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Thanks to all. I am leaning toward a carb/diaphragm problem. It’s funny, it fires right up but quits as soon as that first pull of fuel burns.
 

J D

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Thanks to all. I am leaning toward a carb/diaphragm problem. It’s funny, it fires right up but quits as soon as that first pull of fuel burns.
Pretty typical of stiff diaphragms... You pump fuel into the carb which gets the saw to fire up but then a diaphragms lack of flexibility means either the fuel pump doesn't work, a valve doesn't seal, or the metering doesn't move far enough
 

dboyd351

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Look at the lines and bulb. The fuel should move from the carb to the bulb, then flow back to the tank.
^^^ This^^^
It is the opposite of what most people think it should be. The primer bulb should be pulling gas thru the carb not pushing gas into it. If it is pushing gas into the carb I guarantee it won't run worth a crap.
 

Patrick1903

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The bulb may also say “In” under one of the fittings. That is where the fuel line from your carb goes “in” to the purge bulb. The other fitting on the purge bulb connects to the line that goes back to your fuel tank.
 

Rooshooter

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I replaced the purge bulb on a poulan pro pr5020. The saw sat unused for a while and the bulb cracked. Prior to that, the saw ran great. After I replaced the bulb, I can start the saw easily but it stalls almost immediately as the gas I choked into the carb burns. choking the saw to start is like giving the engine a shot of gasoline. After it starts, the saw quits. Could this be because I reversed the fuel lines? I can draw gas into the carb to start but I can’t get any fuel from the tank to the cylinder after that. Is this a bulb /fuel line issue or something else?
1640664033933.png
side nipple is fuel supply line
 
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View attachment 951671
side nipple is fuel supply line
Yes, on some models, I have seen folks have the fuel supply line hooked into the "primer bulb" and it would only run a second or two. I guess the primer was forcing a bit of fuel through the carb for it to run a second or two.
Many folks are looking for it to prime just like their pushmower.
 

AxFan20

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I replaced the purge bulb on a poulan pro pr5020. The saw sat unused for a while and the bulb cracked. Prior to that, the saw ran great. After I replaced the bulb, I can start the saw easily but it stalls almost immediately as the gas I choked into the carb burns. choking the saw to start is like giving the engine a shot of gasoline. After it starts, the saw quits. Could this be because I reversed the fuel lines? I can draw gas into the carb to start but I can’t get any fuel from the tank to the cylinder after that. Is this a bulb /fuel line issue or something else?
Try to remember that the (S)hort nipple on the purge bulb (S)ucks. It is connected to the carburetor. The long nipple on the purge bulb returns fuel to the tank.
The diagram is correct , with one thing. The fuel line from the carburetor to the purge bulb is probably the shortest line in the system
 

Backstage

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Thanks to all. I am leaning toward a carb/diaphragm problem. It’s funny, it fires right up but quits as soon as that first pull of fuel burns.
Pull that thing!

Something to check first though? Put a pressure tester on the fuel intake. You can usually do it without removing the carb. You should have good 7psi minimum seal for pressure and vacuum. If not your metering needle is probably fubar.

Let us know how it comes out!
 

redunshee

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Thanks to all. I am leaning toward a carb/diaphragm problem. It’s funny, it fires right up but quits as soon as that first pull of fuel burns.
Expanding on Harley T's post. The tank fuel line attaches to the carb and the suck side of the pump attaches to the other side of the carb. IN other words you're sucking fuel from the tank, into the carb and finally into the bulb. The excess fuel goes back into the fuel tank from the push side of the bulb. When the saw is running you can see fuel swirling inside the bulb.
 

Patrick1903

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Could it also be starving for fuel from an old fuel filter? Maybe pull filter off and make sure that’s not a problem (if you don’t have a new filter handy to test with). Also your fuel is clean and new?
 

Softdraw

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Thank you. I intend to tackle the problem this weekend. I watched the video someone provided but it didn’t answer my question. It was a good vid, though: assuming I got the lines correct, is there a way short of changing the carb to soften the diaphragm? Would carb cleaner work, or should I just change the carb entirely?
 

Backstage

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Nothing I’m aware of to soften a diaphragm that’s hardened. If it’s gunked up, varnished, or the like, then yes, carb cleaner. Otherwise replacing the diaphragm usually just means a few little phillips screws.
 

Patrick1903

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I’ve heard of people using break fluid (or power steering fluid?) to soak them and soften a metering diaphragm, in a pinch. Not sure if that would work the same with a fuel pump diaphragm.
Otherwise find your carb manufacturer and model (often printed/inscribed on carb) and either buy a gasket/diaphragm kit, a complete repair kit, or just replace the carb. I prefer one of the repair kits first. I hate to throw a potentially good carb body away.
 
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