Walbro WT 688-1 Rebuild

MarkyZ

Forum Newbie
Joined
Jan 25, 2011
Threads
2
Messages
4
Hey Everyone!

This is my first post on this forum and i'm hoping you guys can help me out. I'm rebuilding a WT Walbro 688-1 carb and was thinking about replacing the screen on the check valve (that lets gas into the "high" jet). I didn't know how to do it so was going to leave it alone... but then a friend of mine tried to pry it out with a pick! Now the screen is damaged so it isn't much of a valve and it still isn't out! Was hoping someone on here can tell me how to remove it so i can replace it!

Oh and check out the picture, I have circled the check valve in question.

Thanks!

Mark
 

Attachments

  • carb2.jpg
    carb2.jpg
    191.1 KB · Views: 25

ILENGINE

Lawn Pro
Joined
May 6, 2010
Threads
39
Messages
9,855
The check valve can be removed with some effort but you may be better off just replacing the carb. Cost of complete carb may not be much more than repair the carb you have now. Leaking check valves are a common problem with newer carb and sometimes are cheaper to replace than carb kit plus your time involved.


What is this carb off of?

The walbro tool to remove it is a small slide hammer, but I have removed them by screwing a screw into them and then gently wiggling and pulling to remove it them drive in a new one and hope it doesn't leak when your done.
 

MarkyZ

Forum Newbie
Joined
Jan 25, 2011
Threads
2
Messages
4
The check valve can be removed with some effort but you may be better off just replacing the carb. Cost of complete carb may not be much more than repair the carb you have now. Leaking check valves are a common problem with newer carb and sometimes are cheaper to replace than carb kit plus your time involved.


What is this carb off of?

The walbro tool to remove it is a small slide hammer, but I have removed them by screwing a screw into them and then gently wiggling and pulling to remove it them drive in a new one and hope it doesn't leak when your done.

Thanks ILENGINE!

It's off an Ice Auger powered by a Solo powerhead.

Any idea where I can get a new check valve? All the small engine shops around here haven't been very helpful with regards to getting parts for the Walbro, which is odd considering how common these carbs seem to be.

I've uploaded the Parts List and Diagram I got from Walbro. If someone can help me identify the Check Valve part# it would be very much appreciated!
 

Attachments

  • WT-688A_diagram.jpg
    WT-688A_diagram.jpg
    185.3 KB · Views: 15
  • WT-688A.jpg
    WT-688A.jpg
    132.2 KB · Views: 13
Last edited:

imcomininhot

Forum Newbie
Joined
Aug 31, 2013
Threads
0
Messages
4
I bought a 2002 bv1800 weedeater brand blower vac off a neighbor thinking that I'd be lucky enough to get it running. changed the broken/cracked fuel lines. cleaned the spark plug, nothing yet...
so, troubleshooting, I looked it over, removed the muffler and tried to run it - nothing. looked at the bulb, pushed it a few times, and it got stuck in the downward position. tried to just fire it up to see if anything would happen, nothing... then, poured a bit of fuel in the carb and presto - she fired up for a second or two.
obviously it's the fuel delivery. ordered a carb kit, just rebuilt it this morning. cleaned out the dismantled carb with some carb cleaner and my air compressor. cleaned the little internal rubber piece that sits under the primer bulb by removing it, spraying it out, again with the carb cleaner and air. put it back together, now the bulb pumps up real good like it's supposed to, without manually dumping fuel into the carb.
My problem is that it's still not getting fuel. obviously something must be blocking the fuel from getting into the equation.
Any guesses as to what I might've missed or should thing bout cleaning too?
What if I adjusted the L side needle a bit more...? maybe that would allow more fuel to get in there.
I'll shut up now. thanks in advance.
 

ILENGINE

Lawn Pro
Joined
May 6, 2010
Threads
39
Messages
9,855
When you release the primer bulb does it sound like it is sucking air through the middle of the carb. If so then there is a check valve stuck open, and your options are to replace the check valve, or replace the carb. Happens about 50 percent of the time on carb rebuilds. I have about got to the point of not even repairing the carbs on equipment with primer bulbs.

Sometimes if you keep attempting to prime you can get them to seal about 10 percent of the time.
 

imcomininhot

Forum Newbie
Joined
Aug 31, 2013
Threads
0
Messages
4
When you release the primer bulb does it sound like it is sucking air through the middle of the carb. If so then there is a check valve stuck open, and your options are to replace the check valve, or replace the carb. Happens about 50 percent of the time on carb rebuilds. I have about got to the point of not even repairing the carbs on equipment with primer bulbs.

Sometimes if you keep attempting to prime you can get them to seal about 10 percent of the time.

would you be referring to the the black rubber piece that sits underneath the primer bulb that has a hole in the top, and slit in the bottom? I guess that would be a check valve in and of itself - one way valve. Or would you be referring to another check valve deeper, less accessible within the carburetor ?
I'm just thinking about it now. I guess that's the only check valve in that carb, if it was clogged or stuck open, it would definitely give me problems... I guess what my problem is now, is now that I am getting fuel, Now I need to configure the settings,
... Unless - if there is somewhere I might've not cleaned well enough that is giving me a bad flow problem, hence my problem with bogging down and dying.
Perhaps I need to clean the air filter - it may be dirtier than I think. Lacking air would make it bog down.
 
Last edited:

imcomininhot

Forum Newbie
Joined
Aug 31, 2013
Threads
0
Messages
4
I guess some of us that don't understand these carbs speculate easily too much and that might be half the problem - Does the KISS theory apply with small engines? (Keep it Simple Stupid)
are there any other jets or check valves that can get clogged inside these small carb's that are frequently missed?
 

Fish

Lawn Pro
Joined
Aug 2, 2013
Threads
11
Messages
5,123
I guess some of us that don't understand these carbs speculate easily too much and that might be half the problem - Does the KISS theory apply with small engines? (Keep it Simple Stupid)
are there any other jets or check valves that can get clogged inside these small carb's that are frequently missed?

Yes, for you you should just replace the carb. Poulan sells the carb cheap enough!!!!
 

ILENGINE

Lawn Pro
Joined
May 6, 2010
Threads
39
Messages
9,855
would you be referring to the the black rubber piece that sits underneath the primer bulb that has a hole in the top, and slit in the bottom? I guess that would be a check valve in and of itself - one way valve. Or would you be referring to another check valve deeper, less accessible within the carburetor ?
I'm just thinking about it now. I guess that's the only check valve in that carb, if it was clogged or stuck open, it would definitely give me problems... I guess what my problem is now, is now that I am getting fuel, Now I need to configure the settings,
... Unless - if there is somewhere I might've not cleaned well enough that is giving me a bad flow problem, hence my problem with bogging down and dying.
Perhaps I need to clean the air filter - it may be dirtier than I think. Lacking air would make it bog down.

Look at the picture by the earlier poster in this thread for a picture of the check valve I was refering to. If it sticks open the primer will suck air, and not prime. if it sticks shut the engine won't start or run on its own.
 
Top