Did Briggs put out a service bulletin about dirt/primer bulb?

12 years ago

I posed this question earlier this year and got no responses.

A local dealer told my cousin that the small hole in the primer bulb was sucking in dust and fouling the carburetor. I had not heard of this problem before.

Today, for the first time, I have seen it.

The motor was very dusty and showing signs that it's used in dry, dusty conditions. The air filter was also coated with fine dust.

I removed the carb and cleaned it internally and the motor ran almost 100%, but by putting me finger over the hole in the primer bulb, the engine picked up RPM and ran perfectly. I replaced the bulb with another with no hole and ran the motor for about 15 minutes perfectly.

It's another thing to check when rebuilding a carb doesn't quite make the motor run 100%

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Comments (8)

tomplum
12 years ago
A Quantum series I assume? If it is actively sucking in dirt, then that would indicate to me that the element is plugged. We've seen that fine dirt makes it's way into the bowl in these situations. The carb itself is vented into the airbox on the filtered side. That primer passage also leads to the bowl. What is your theory that plugging that hole made it run better?
baymee
Original Author
12 years ago
I didn't look up the name, but it's an OHV.

Putting my fingertip over the primer hole made it audibly run smoother and slightly higher RPM.

Drawback: It doesn't prime correctly with the unholy bulb. So, back to the future again.

There is a local dealer who covers all the holes with a dab of silicone. Didn't work for me.
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tomplum
12 years ago
Sometimes shops get a bug up... been there done that. Intek engines many times spec a different airbox gasket than the "normal" flat head. Do you suppose it is possible that the wrong gasket was installed? Seriously, try to think this through.
baymee
Original Author
12 years ago
When I removed the air filter housing, I noticed that the gasket is different. I put a new spec bulb on and it runs fine now. ....one of those freaky things, I guess.
GeoT
12 years ago
Just wondering . . .

My Briggs Quattro (10A902 2189 B3) and Briggs Sprint II (98902 0313 01) --- both have a solid primer (no hole).

My Briggs Quantum (12H802 0632 01) has a primer with the hole in it.

Does the diaphram type carburetor on the Quattro and the Sprint require the no hole (aka wet) primer, while the Quantum with a float bowl take the one with the hole (dry primer)?

From researching primers after the Quattro wouldnt prime -- it seems the wet bulb draws fuel directly from the tank, while the dry primer pushes air into the float bowl which then lowers the float and opens the needle valve and introduces fuel to the carburetor throat.

Am I understanding this correctly? Thanks for any info!
baymee
Original Author
12 years ago
Does the diaphram type carburetor on the Quattro and the Sprint require the no hole (aka wet) primer, while the Quantum with a float bowl take the one with the hole (dry primer)?

Yes
GeoT
12 years ago
Thanks!
hawkeyechuck
12 years ago
Unhook fuel line from carb. drain gas into can. unhook line from gas tank. take it to a small engine repair shop or hardware store and get the same size hose with a filter in the middle. hook it back to the two ends.

OR you can replace it...

Here is a link that might be useful: Primer Bulb