Briggs Quantum refuses to prime

[HawkeyeScott]

Older, classic Briggs mower engine with the panel air filter on the right side and primer bulb built in to the panel cover. Fixing up for my kid to mow yards this summer. Cannot get it to prime.

Have switched out carbs and primer bulb/air filter cover from my working mower to test. Actually have cleaned and tried two carbs and neither works. Mower starts after about 12 hard pulls and runs fine. It also restarts easily. I mowed with it yesterday.

I feel like all the usual variables have been addressed through troubleshooting with parts from my mower that primes easily. Transferred to this machine they don’t work the same. Now thinking about things like fuel line and gas cap, but again, it runs fine once you pull the starter rope enough.

Worked on quite a few mowers over the years but haven’t come up against this issue, at least to this degree. Open to any ideas. Thanks a lot! Happy Easter.

 

[Brian123]

Carburetor Spray Cleaner, I have a 29-year-old Briggs Engine on my Toro Super Recycler. I take the air filter panel off, spray a shot of carburetor cleaner and the mower starts on the 1st pull. I have been doing this for 15 years, I cannot get the primer bulb to work, I even installed a new1, no difference.

 

[The_Eric]

I've ran into that too and just attributed it to low quality replacement parts

 

[Fordiesel69]

youtube it. The air filter housing plate just blow air into a hole on the carb. The plastic warps. You canb fix with some tape or two gaskets doubled up.

 

[HawkeyeScott]

youtube it. The air filter housing plate just blow air into a hole on the carb. The plastic warps. You canb fix with some tape or two gaskets doubled up.

Thanks. I have watched most videos on the subject and all point to the things I’ve done. And, like I said, the same filter cover/primer bulb/gasket that works on a similar mower will not produce a prime when switched over to the mower I’m trying to solve.

Was hoping someone here might have another idea…

 

[Fordiesel69]

So, In theory you should be able to hold the carb in your hand, hook a hose up to it so it is full of fuel and any blowing in the primer hole will blurp fuel from the bowl up into the carb throat..

The issue **must** be with the fitment of the air filter housing to the carb. Or the bowl is not full enough.

On edit, some mount with 3 holes. Two holes will hold the air filter housing plate to the carb body, and another bolts into a piece of metal on the engine. Is there a change the metal is warping the housing plate on the one engine?

 

[mk378]

The carb and air cleaner gasket must be the type that is designed for air prime. There are many variants of these parts that look almost the same.

A workaround is to use starting fluid for that first start. It can be sprayed in the slots of the filter cover without disassembly.

 

[Lubener]

Air leakage due somewhere due to pimer bulb, fuel pickup in the tank, fuel lines ard any gaskets which are in the priming circuit.

 

[Nukeman7]

Check out the video below. I have had luck sealing the leaky air filter housing gasket to the carburetor intake port by applying a thin layer of RTV on both sides of the cardboard gasket before bolting it back together.

 

[nbpt100]

I have used as many as 3 gaskets or just purchased a new air fitter cover. I never tried to heat it up and bend it. I could see that making it worse if you are not very careful. He did a good job of explaining the problem and troubleshooting. In the mean time you can use some kind of starter fluid or tip the mower carb side up for about 5 or 10 seconds and that will allow gas to leak in to the throat of the carb and there is your red neck gravity primer trick. You may have to do it 2 or 3 times.

 

[HawkeyeScott]

Closing the loop; I had some time to work on the mower this past weekend. A Yeti sticker cut to match the shape of the channel on the back of the air filter cover, along with the gasket, did the trick. It starts after about 8 pushes on the primer bulb.

 

[Silverado12]

Assuming you have the correct parts, you can take a piece of electrical tape and put it over the air "channel" in the breather and place your old gasket back over that. The problem is the breather warps. You could get a new breather for the mower, though but this way is free.

 

[nbpt100]

Closing the loop; I had some time to work on the mower this past weekend. A Yeti sticker cut to match the shape of the channel on the back of the air filter cover, along with the gasket, did the trick. It starts after about 8 pushes on the primer bulb.

if you remove the air filter and bend back the plastic or metal piece that covers the throat of the carb you can look in and watch it prime as you press the bulb. You should see the gas come up the emulsion tube and into the throat. If it takes 8 primes it is still not sealed 100% but if you get it working and you are ok with that , you are good to go.

One other consideration is the float may be set too low and not allowing enough gas into the bowl.