"Automatic" Choke -Briggs

[Mek-a-nik]

121s02 0011-F1 140409 56 on a Briggs Pressure Washer M- 020599
Upon testing it, it ran fine w/ no load. Pulling the trigger made the choke flap pulsate, and it got worse until it barely ran (choke was closing).
I can hold the choke flap open, it runs good then.
Either the choke return spring, or the thermostat is holding the choke too tightly.
I saw on another thread where the 593208 stat is a problem. This one calls for a 798938. Do they have the same issue?
Link to engine IPL: http://bsintek.basco.com/BriggsDocument ... Vj5K1w.pdf

[bgsengine]

121s02 0011-F1 140409 56 on a Briggs Pressure Washer M- 020599
Upon testing it, it ran fine w/ no load. Pulling the trigger made the choke flap pulsate, and it got worse until it barely ran (choke was closing).
I can hold the choke flap open, it runs good then.
Either the choke return spring, or the thermostat is holding the choke too tightly.
I saw on another thread where the 593208 stat is a problem. This one calls for a 798938. Do they have the same issue?
Link to engine IPL: http://bsintek.basco.com/BriggsDocument ... Vj5K1w.pdf

Sounds to me like your choke linkage or t-stat needs a bit of adjustment or you need to check for any obstructions to air flow. may even have an exhaust issue if the thermostat is moving to allow choke to close.

Adjust ReadyStart® Choke Link
Perform this adjustment while the engine is cold.
1. Using pliers, bend adjusting loop (M, Figure 1-11) on choke link (N) until choke
lever gap measures 0.000 - 0.060 in. (0.000 - 1.52 mm). When properly
adjusted, the choke plate will be fully closed. Reshape wire to keep it parallel (P) after adjusting loop.

that would probably be the place to start, i would think - and obviously while doing the adjustment, you'll be inspecting the rest of the system. - a peek at Service Bulletin 760 may be helpful as well -

5. While the engine is cold, visually check whether the choke valve in the carburetor is fully closed.
If the choke valve is not fully closed, go to Step 6. If the choke valve is fully closed, repeat Steps 1 – 4.
• Model Series128T00 and 128L00 (700 Series) ONLY – If the choke valve is fully closed, skip to Step 7.
6. While the engine is cold, check the thermostat arm and air vane for freedom of movement:

• The thermostat arm must not contact the edges of the air vane hook. If necessary, use light
finger pressure to adjust the arm to the proper gap using the bosses molded into the air vane hook for
reference, resulting in a clearance of approximately 1/16” to 1/8” required for the
choke to close completely.

The thermostat arm should rotate easily fore and aft (no binding or sticking) and must spring back to
the cold stop position when released. If the thermostat sticks, replace it.

• The air vane should move freely from full-closed choke to full-open choke and should spring back to
full-closed choke when released. If the air vane sticks, check the spring for stretching or other damage,
and check for dirt, debris, or grass clippings which may impede air vane motion. Replace the spring and/
or remove debris or grass clippings and clean the air vane pivot joint as necessary.

[Mek-a-nik]

This engine has no air vane. Will any of this info still pertain?

[bgsengine]

in that case, no - you mentioned 593208 kit, so I just assumed it was the ready start system.

since this one you have is not, then no it would not be the same sort of issue, but I am pretty sure that you'd need to go over the adjustments - generally with this type of thermostat if it moves freely and far enough for choke to open and close fully, there's nothing wrong with it - they either work or they don't - Have not seen an engine yet with that particular type of choke, so can't tell you from experience on that one.. but the IPL does indicate the same sort of adjustable choke link, so I think you will need to determine the type of starting system and look it up in the briggs service manual.. I plan to read up on it too myself, but probably won't come up with the info in a timely manner to be of any help to you at the moment.

[Mek-a-nik]

I only mentioned the 593208 as a reference to the other thread. The 798938 I Mentioned is what I need. I know you're a busy man and don't have time to read entire posts.
I ordered all related parts and will report back as to how I made out.
Thanks.

[Mek-a-nik]

I installed the new thermostat today.
I looked in the Briggs OHV manual, https://drive.google.com/file/d/0B-g4Tp ... I4S0E/view , and didn't see any reference to the auto-choke. My computer doesn't show the figures, just shows the block the figure is in, so I don't know if it would help anyway.
I ran it and it had the issue a bit when it was cold, then it ran very well as it warmed up.

Thanks for the help!

[KE4AVB]

You need to be looking the following manual
https://drive.google.com/file/d/0B-g4TpKUJnh7bzF5cWJxT1hnVTA/view?usp=sharing

[Mek-a-nik]

You need to be looking the following manual
https://drive.google.com/file/d/0B-g4TpKUJnh7bzF5cWJxT1hnVTA/view?usp=sharing

Yep, that's it! I can even see the figures. Thanks, KE4AVB!
People must complain a lot about primers and chokes for Briggs to try to make this work. Automatic chokes were always a PITA on cars, too.