Thread: Poulan 3400 not getting fuel...after new lines.

I have been trying to get my Poulan 3400 saw to run. I have replaced both fuel lines...though I am not exactly sure where the vent line is supposed to go. Does it just run back behind the tank and sit there? Or is it supposed to hook into something? After replacing both lines the saw will still not pump any gas into the carburator. It runs great for a few seconds when I pour fuel directly into the carburator, but then, obviously, quits because it does not continue to get fuel. Any suggestions?

Thanks

If I remember correctly the vent line should carry a duck-bill valve just inside the tank (to let air in to prevent vacuum lock in the tank). I place a fine-thread set screw in the outside end of the vent line to let air seep by but keep trash from getting to the duck-bill valve. If your fuel line and fuel filter/sinker are good but the carb is not pumping fuel then the problem is likely in the carb -- a carb kit and a good cleaning should fix things.

Make sure the bolts are tight that hold the carb to the cylinder.
make sure the fuel filter isn't clogged.
carb might need to be cleaned and/or rebuilt - the diaphram could be shot, the inlet screen might be clogged, or the metering lever might need adjustment

I'm sure others will chime in with other suggestions, but these should be a good start

Originally Posted by galde

If I remember correctly the vent line should carry a duck-bill valve just inside the tank (to let air in to prevent vacuum lock in the tank). I place a fine-thread set screw in the outside end of the vent line to let air seep by but keep trash from getting to the duck-bill valve. If your fuel line and fuel filter/sinker are good but the carb is not pumping fuel then the problem is likely in the carb -- a carb kit and a good cleaning should fix things.

The vent hose just dead ends above the tank. I also used a screw to keep debris out of the hose.

Originally Posted by radar_17

I have been trying to get my Poulan 3400 saw to run. I have replaced both fuel lines...though I am not exactly sure where the vent line is supposed to go. Does it just run back behind the tank and sit there? Or is it supposed to hook into something? After replacing both lines the saw will still not pump any gas into the carburator. It runs great for a few seconds when I pour fuel directly into the carburator, but then, obviously, quits because it does not continue to get fuel. Any suggestions?

Thanks

Hi Radar,

Can you give more info on what you have tried?

Of course the common things are fuel filter in the gas tank, hoses and carb repair parts plus adjustments.

The vent hose should not affect the running of the saw in the short term regardless of where it is run.

One of the most overlooked 2 cycle fuel problems is the lower part of the engine jug (cylinder). The lower end of the cylinder is essentialy the fuel pump. If the lower end is damaged, you will not create a vacuum in the crankcase to draw the fuel/air mix in.

The engine can have great compression (on the top end) and still fail to run.

I always (within reason) remove the muffler on a 2 cycle and inspect the piston/cylinder before beginning a repair.

If I remember correctly, the 3400 has a chromed piston, but the jug is not chromed. They tend to score low on the exhaust side. By removing the muffler and spark plug, you can get good light to it and look through the spark plug hole to the exhaust side of the cylinder. If there is any damage, then save your money and time.

Good luck,
echoman

this is what your piston should look like i know the listing says out of stock but i still have one on the shelf i will let go for $ 20.00 plus shipping

it just dont have the clips for the retainer see how the chrome color very shiny but on the above if you need a piston i have one you just have to send me a msg and i can fill you in on how to pay etc.

like echoman says check that cause it could very well be a issue with compression cause its not having a suction its like a pump engine if it looses its prime it dont pump same scenerio on the crankcase if it looses its compression it wont receive the suction to prime the fuel
calvin




http://www.cmsmallengines.net/poulan...30-010314.html

Originally Posted by radar_17

I have been trying to get my Poulan 3400 saw to run. I have replaced both fuel lines...though I am not exactly sure where the vent line is supposed to go. Does it just run back behind the tank and sit there? Or is it supposed to hook into something? After replacing both lines the saw will still not pump any gas into the carburetor. It runs great for a few seconds when I pour fuel directly into the carburetor, but then, obviously, quits because it does not continue to get fuel. Any suggestions?

Thanks

Echoman covered very well the possibilities. If the Piston is in good shape I'd bet a dollar to a dime its the carb. Get a rebuild kit and replace diaphragms etc. Also be sure to set the metering lever correct. On the Walbro HDB is set flush with the carburetor body.

Originally Posted by galde

If I remember correctly the vent line should carry a duck-bill valve just inside the tank (to let air in to prevent vacuum lock in the tank). I place a fine-thread set screw in the outside end of the vent line to let air seep by but keep trash from getting to the duck-bill valve. If your fuel line and fuel filter/sinker are good but the carb is not pumping fuel then the problem is likely in the carb -- a carb kit and a good cleaning should fix things.

On all of my old Poulans(6) the duckbill is missing though I know what you're referring to. I'm intrigued by your use of a screw in the vent line though, as I've simply used a short piece of large diameter plastic fuel line. Question- wouldn't the screw keep hot air in the tank? If not its a great idea.

It runs! I actually don't know what happened. I went out to work on it yesterday and found that there was fuel in the line. I had done nothing. So, I fired it up and it kept pumping! I just neet to get the idle adjusted and the high and low adjusted now.

Thanks for all of the responses. I figured I'd be lucky to see one or two responses by now, so I was very impressed to find 7 or 8 within 24 hours.

I was unable to find any 'duck-bill' valve. I don't think there are any cylinder problems as the engine has actually had very few hours of use though it's around 15 years old, and it's been well taken care of by the original owner. I have noticed that it is a bit difficult to get the carb adjusted right, but once it is the saw runs nicely.

I will put a screw in the end of the breather tube to help prevent particles...good suggestion...thanks.

I appreciate the help...now know right where to go for help in the future.

Thanks,

Originally Posted by radar_17

It runs! I actually don't know what happened. I went out to work on it yesterday and found that there was fuel in the line. I had done nothing. So, I fired it up and it kept pumping! I just neet to get the idle adjusted and the high and low adjusted now.

Thanks for all of the responses. I figured I'd be lucky to see one or two responses by now, so I was very impressed to find 7 or 8 within 24 hours.

I was unable to find any 'duck-bill' valve. I don't think there are any cylinder problems as the engine has actually had very few hours of use though it's around 15 years old, and it's been well taken care of by the original owner. I have noticed that it is a bit difficult to get the carb adjusted right, but once it is the saw runs nicely.

I will put a screw in the end of the breather tube to help prevent particles...good suggestion...thanks.

I appreciate the help...now know right where to go for help in the future.

Thanks,

Good to hear of your success. I've been collecting old Poulans(3400,3700 and 4000) for a while. I like their simplicity and to be honest my 3400 cuts as well as my new MS260( sure is sweet though). I've never used a screw in the vent line though. Good idea if I can get past the question of: How does air vent past the screw? It must or this method wouldn't be used but maybe someone can educate me.