Poulan 31cc PB300 gas trimmer, only runs with choke on.

revalation22_5 · #1 09-07-2007, 01:57 AM

First off I am amazed at all the imformation on this site, You guys do a great job.

now for my problem. What I thought was gonna be a general carb cleaning for my father in law has me really scratching my head. He asked me to look at his Poulan Pro PB300 trimmer. Said it would not idle and dies when you try to give it gas. I figured it would be simple and I would just have to clean the carb and maybe replace the diaphgram. so first i cleaned the carb but that did not help so I went to order a carb kit and was told I would have to buy the whole carb no big deal. so i bought the carb and installed it. but it still does not want to run with the coke off. I have replaced
The Fuel Filter
The Fuel Cap (in case it was not venting)
The Carb
The Primer bulb.
I
It will start with the choke on and run and rev up, but when the choke is off it will idle for a few seconds and when you try to give it fuel it will die.

It does not look like the high and low circuts are adjustable because they have a odd cone shaped thing where the screws normally are.

I have also forgot how to route the lines.

Any help would greatly be apprecaited.

thanks

geogrubb · #2 09-07-2007, 12:48 PM

Even though you now have a new carb it can have the same problem as the old one, the carbs are manufactured and the set on the shelf for extended periods of time and the diaphgram and gaskets dry out. Anyway, I think your trimmer has a Walbro WT628 carb and kits are available, as of right now www.oscar-wilson.com has Diaphgram kit D20-WAT for $4.17 with 33 in stock and Repair kit K20-WAT for $8.23 with 48 in stock. If that is not the carb or proper number post back with what is on the trimmer or the new one you purchased and we will try to chase it down. I have seen posts on this forum to make an adjustment tool is drill a 9/64(I think that is the size)hole in the end of a piece of 1/4" dowel stock then tap it over the screws to create a tool for adjustments or removal. For the fuel lines I suggest going to your local Wal-Mart and check the lines on a trimmer, they sell Poulan, that is the surest way to get the lines correct. Have a good one Geo

geogrubb · #3 09-07-2007, 06:42 PM

After further checking the 31cc engine may have a Zama Carb and according to the parts list there is no repair kit available for the C1U-W32 carb. However, the C1U-W32 uses repair kit RB-142 and diaphgram/gasket kit GND-78. You can order either at the following.

www.hhlce.com/shop/zama/zama-Index.htm

The RB-142 is $8.95 and the GND-78 is $5.95
Have a good one. Geo

revalation22_5 · #4 09-07-2007, 06:47 PM

you are correct it is a WT628 carb. I may order a kit for it just to be sure, I really want to get this thing going. Is there anything else it could be?

geogrubb · #5 09-07-2007, 07:17 PM

You shouldn't need the whole kit just the diaphgram/gasket kit. Unless you have an air leak somewhere which will create the same symptoms. While you have it running you might spray some carb cleaner along any mateing surfaces(engine housing,carb to crankcase, etc.) to see if the engine tempo changes which would indicate a leak. Have a good one. Geo

hec1943 · #6 11-09-2007, 05:25 PM

I have a Poulan leaf blower and I have found that the exhaust port will begin to build up a carbon deposit after many hours of use. This causes the engine to run slow and somewhat rough. Take the exhaust muffler off and check the port for carbon build-up.

HEC

30yearTech · #7 11-09-2007, 06:32 PM

....

geogrubb · #8 11-10-2007, 12:29 AM

Did anyone realize this post is 2 months old without a response from the original poster. Have a good one. Geo

30yearTech · #9 11-10-2007, 09:45 AM

Quote:

Originally Posted by geogrubb

Did anyone realize this post is 2 months old without a response from the original poster. Have a good one. Geo

Ha ha...Apparently not, I know I never paid any attention to the date.

Have a great one

niteman9 · #10 06-14-2009, 12:08 AM

I know this thread is over a year old but I am having the same problem. I need to know how to connect the fuel lines. So could someone in the know take his diagram and show how to connect the fuel lines. I am about to run over this thing with my truck.

niteman9 · #11 06-14-2009, 12:31 AM

Here is the way I have it now and cant seem to get it to start.

Lawnmowertech · #12 06-14-2009, 02:06 PM

niteman have you checked the filter ? to make sure it is ok even the purge pump bulb to see if it has a crack in it or air leak ?

the lines look ok cause you have the fuel coming into the diagphram end of the carb going to the bulb and going back into the tank you can try switching it to see if it works but if it dont work then i would take and look at the other possible causes

ignition system

primer system

etc.

check the muffler also to see if it is plugged up

hope this helps

calvin

niteman9 · #13 06-14-2009, 02:24 PM

Thank for the reply. The fuel filter, tank, carb, and fuel lines are all new. The primer bulb does not have any cracks. If I cover the shorter fitting and press the bulb does not release until you remove your finger. It seams like this fitting on the bulb is pushing gas when depressed and pulling when released. Is this correct? How do I check the bulb an make sure it is working correctly?

Also with the fuel lines in this position gas runs out the air cleaner side when primer is pushed.

Lawnmowertech · #14 06-14-2009, 07:47 PM

Quote:

Originally Posted by niteman9

Thank for the reply. The fuel filter, tank, carb, and fuel lines are all new. The primer bulb does not have any cracks. If I cover the shorter fitting and press the bulb does not release until you remove your finger. It seams like this fitting on the bulb is pushing gas when depressed and pulling when released. Is this correct? How do I check the bulb an make sure it is working correctly?

Also with the fuel lines in this position gas runs out the air cleaner side when primer is pushed.

sounds like its working properly

switch the lines around on the carb see what happens

niteman9 · #15 06-14-2009, 10:09 PM

I switched the lines on the carb and was able to get it started. Put the string trimmer attachment on it and used it for a while. When I was done I noticed it was on 1/2 choke. When I opened the choke it would die. I pulled it apart again and swapped the lines back on the carb. Couldn't get it started. Swapped them back and got it started again. This time it would run with the choke open. So well see how it works. Thanks for the help.