# Fixed jet on diaphragm carburetors



## humminbird2 (Jan 4, 2009)

How do you remove the cap on fixed jet for WT 628 diaphragm carburetor. I have cleaned carburetor with choke Sea Foam and compressed air, but the high speed jet is still plugged, I think. All new gakets and diaphragms. Engine will not run at high speed. What do I do next? Waiting for a reply. Thanks.
Humminbird2?


----------



## 30yearTech (Sep 14, 2006)

If your talking about limiter caps on the adjustment screws, the usually just pull off with a pair of pliers.


----------



## paulr44 (Oct 14, 2008)

If it is a fixed jet, there's only so much you can do. Sometimes there are welch plugs under the metering diaphragm you can remove, with fuel passageways being under the plugs that can be cleaned with a small probe, such as a tag-wire. New welch plugs come in rebuild kits. Some main jets are replaceable, but have to be ordered separately. I tried to look up your carb. but Walbro's IPL site is down right now:
http://wem.walbro.com/walbro/family2.asp
That carb. only lists for about $40 - hardly seems worth rebuilding though, unless you need it bad as neither East coast distributor has it in stock presently.


----------



## humminbird2 (Jan 4, 2009)

*Thanks, fellows, for your reply.*

The WT 628 has two fixed jets with each having a longitudinal stem (cap). I did not want to pull the stem off without some advice as I did not want to damage the carburetor. After thoroughly cleaning carburetor, installing all new gaskets, diaphragms, needle needle valve and adjusting lever, the Poulan PPB 200 weed eater will start and run only with choke. When choke is off, engine dies. I believe hi speed jet is plugged, but no way to clean unless I remove jet and clean passage. Do you have any other suggestions other than HI speed jet as cause of problem? Would a faulty manifold gasket cause this problem...poor vacuum??? I appreciate any help you can provide. Thanks in advance.
Humminbird2


----------



## 30yearTech (Sep 14, 2006)

Yes, any kind of leak into the crankcase can cause a similar issue. The IPL for your carburetor does show adjustment screws with caps, The caps are usually plastic and can be removed, however you will destroy the caps in order to remove them.


----------



## humminbird2 (Jan 4, 2009)

Thanks, 30YearTech. OK, I want to remove them to clean out the jets or make adjustments to the screws. Do the caps need to be replaced or will the jet leak without the replacement cap. Are the caps replaceable? By the way, this carburetor is WT-628 and Walbro says the carburetor has no repalceable parts. Do you just throw it away and buy a new one. The carb. kit I bought was WT-628-1 (K20 WAT and D20 WAT). Are these WT 628-1 parts not compatible with WT 628. Thanks again for your help.


----------



## humminbird2 (Jan 4, 2009)

I removed the muffler and shroud and found only an O Ring on the back of the shroud. No gasket. Walbro service manual show only an O ring, I suppose it to keep exhausted oils from leaking around the shroud. In other words, this O Ring, to me, just doesn't give what I would call a tightly sealed area. I don't see this area need to be tightly sealed anyway as it goes to the exit of the muffler. Where am I getting lost here? I'm a novice.
Humminbird


----------



## 30yearTech (Sep 14, 2006)

The adjustment needles and caps are not a serviceable part. Due to State and Federal EPA regulations, they don't want anyone changing the adjustments on these carburetors. They are set at the factory and capped. If you remove the caps and change the adjustments, you are actually violating federal law. You may also need a special tool to remove the adjustment screws as they likely do not have any screw driver slots.

As long as the O-Ring is not torn or pinched and gives a seal, it should be alright to use.


----------



## humminbird2 (Jan 4, 2009)

Thanks again, 30YearTech. I appreciate your help. I will just let the setting stay as is. I will have to buy a new carb.
Humminbird2


----------

