I recently bought a used 3.5 HP Briggs and Stratton. When I first got it, it would only run with starting fluid and choked. The gas tank was coated in rust so I cleaned it to the best of my ability using CLR, and other cleaners and a pressure washer. It is a side shaft engine that uses the fixed Pulsa-Jet carb. I figured that rust had made the one pick up tube (it broke in half when I pulled off the fuel tank) just so bad it wouldnt work. So, I clean the tank, and still no luck. It will only start using carb cleaner and Seafoam, and it will want to die unless you can push the throttle to low (closed) and it will run for ten or so seconds. I removed the carb again and let it soak in carb cleaner (the big paint bucket kind) for two hours and took it out. I figured the fixed jet was clogged since I replaced the other tube. The air that I blow into the fixed jet, I do not know if it os clogged or not. I imagine it is. When I put my mouth up to it and blow into it, air will pass through, just not very fast. my engine is 91212-0022-01. I hit 100+ compression today. Any suggestions?

-Thanks.

 

The most common problem on those old carb's is a bad gasket. If it can't create suction, it will act like its not getting gas. Not sure which exact carb you have... the long one with the choke that you pull out on the end of the carb? It had a side gasket (behind a plate with 2 screws) that would go bad. I often would lubricate them with oil and rub the oil into the gasket with my fingers to get them to work again, but replacement of the gaskets is your best bet. The gasket has a flap that is suppose to open/seal a port. If it gets old/brittle it doesn't seal. Was very common.

If the tube is broken, that might be a problem. LOL You could pick up a used one off ebay or something.

 

I have the one with the choke and throttle controls on the side, where you pull the (handles?) and the choke will close and with the other the throttle will open, etc... I think you are talking about the diaghpram as a gasket? It has four screws, a spring, and a cap. I really cannot tell if its bad or not, it seemed okay to me, wasnt too stiff, i could bend it with my hands. I have the pulsa-jet carb. Its like the upadated one to the choke you pull out of the back. LOL! Dont worry, I got a new tube and brass pipe. No way I am that stupid LOL. It cost about ten bucks for them both. Where can I find a diaphram and are you sure that is what is wrong? You dont think its that fixed jet? Dont mean to sound offensive, I just dont want to dump a bunch of money into this engine.

-Thanks!

 

Yeah I remember the one you mean now. 4 slotted screws and it's got a little spring and spring cap inside the diaphragm, right?

I would take the diaphragm off, oil it up, rubbing both sides of the gasket with your fingers and make sure it's clean and pliable and then put it back on. If it works, great, you're not out anything. If not, they are pretty cheap. Anytime I had a mower that wouldn't run (because of no gas) that was always the problem.

If that is all that was wrong with it, you may have turned all the adjustments on the carb and changed the air/fuel ratio. Seems like the needle setting was all the way in (don't overtighten and scar the needle) then back it out 1 1/4 turns- that was the needle setting I recall from high school small engines class. Then tweak it from there once it's running.

Here is one place you could search for parts. Amazon has everything.

 

I may buy a new one. I dont know how to remove a needle on this carb. There is a screw that looks like it goes into the side where the main fixed jet is. But when I turned it (while the engine was at the lowest RPM for ten seconds) I really do not know if it had any effect at all. I did try it, but the engine died once I could get a screwdriver in my hand, and if I actually got it to run at low RPM for ten or so seconds, still not enough time. But, I will see if the two small engine places have them tommorow. i hope that main jet isnt clogged. Blew it out with an air compressor and still no better air flow. Here is my carb Disassembly, Cleaning and Repair of Briggs Tank-mounted Pulsa-jet Fixed-jet Small Well Carburetor. But I am not sure that I can remove the piece at the bottom of the fixed jet. I tried, but to no luck. I think I have that screw, but I am unsure about a spring.

I wish my high school had a shop or engine class. We had contrstrctuin for 18 weeks and he made us do all of the work at his jobsites that nobody else wanted to. However, I did just graduate from BMW STEP, so I do have that.

-Thanks!

 

LOL, Take it from a carpenter, it sounds like a great way to learn what your first few years on the job would be like. LOL

Oh, and looking at that link... pictures #5 and #13 are the diaphragm I was referring to earlier that would have problems. The flappers go bad inside that pump cover. Bad diaphragm... no pump.

 

So you think that the jet having little airflow is just normal? I have no idea, I am just wondering. The fixed jet by the way. The short one.

Oh, so your first few years were torture? Looks like youre in Nebraska, imagine going to balzing jobsites in the summer and fall (when it is still hot LOL) and him offering a learning experience of how to sweep floors hehe. I did enjoy it though.

 

Yes, there isn't much air that goes through the jets.

My first few years sucked, yeah. Fortunately I outgrew that phase pretty quickly... lol. I guess I was remembering one particular time when I was sent to check on a new co-worker who had no vehicle or phone and was supposed to be sweeping out a house we were working on. (he had been there for hours). So I show up expecting him to be about done. He was sitting on his butt dusting out each stud bay with a paint brush and hadn't even started to sweep the floor. I don't recall what I said to him but I don't think I had learned to be very tactful yet. (that took a few years too!) Ahhhhhh, the good old days.

My boss was a nice guy but also kind of a jack whacker. Very anal and a bit condescending. I suppose I've learned to be a bit like him at times. LOL

 

Okay, well I will let it sit overnight in cleaner and go to the parts store tommorow and see if they have the diaphragm. Hopefully I can get it in store and won't have to wait and I can see if that works!

I feel the same way at the dealership. Since I went to school for BMW, I manage other techs, which mean I have to rely on others competence. Let's just say that...sometimes, I find my lack of faith to be extremely disturbing, yet true and accurate.

 

At lunch I talked to the lady at the law mower shop, she did tell me that she has them in stock, however, we got swamped with cars today at the dealer, so I didn't get off work until 6:00, and by then they were closed. I will pick it up tommrow for sure though, as I do expect to have some extra time. Stay tuned.

 

well, new diaphragm gave me no positive results, sadly. Tank is clean and I have no idea why fuel is not being pumped into the head. It does have spark, as starting fluid will allow for a short run time.

 

Turn the needle in until it stops. (Don't overtighten) then back it out 1 1/4 turns and try again w/ the start fluid at half throttle.

 

Will do sir. I will see if that helps first thing tommorow. I did feel of my old diaphragm and compared it to my new one, and yes, I do notice a difference, the newer one is much...moister? The old one, without gas on it, did seem kind of stiff compared to this one.

 

Still, no such luck. Ironically though, when I put the carb to the engine the first time after cleaning, it started and died just like before, I sprayed nothing into the engine. I turned the screw and still have no luck. It will only start if I spray fluid, and even then it only runs for a few seconds.

 

I went and put seafoam in the choke and it ran pretty smoky until the seafoam ran out. It somehow, still isn't getting any gas. I am not sure how, as I cleaned it well and put a new diaphragm in it. The screw seems to have no real effect on how it runs, sadly. Is there any other ideas? Maybe the well in the tank doesn't have any fuel in it, not allowing for any fuel in the carb maybe? Any other suggestions or ideas?

 

I got it to run! But I needed the screw turned about four times outwards...LOL. Now, it seemed that with all the shaking, the screw moved a little, out of the position for running smooth. Is there anyway to keep it secured? And, is there a way to get it to start with choke off?

-Thanks, Charlie

 

Non-permanent locktite liquid... just a single drop on the threads.

 

Now, it is not wanting to start at all. I was able to get it to turn over today, but now it just doesnt even want to pop, even with fluid in the head and the carb. It does this sometimes and did it before, but a new plug made it work. I made sure the gap on the arms of the magneto were 0.09' to 0.012'.

 

okay, here is my problem. I was starting it and I was moving the screw to help it run better when it died. I tried to start it and it would not start, so somehow I moved the throttle to ground the kill switch. How? I do not know. It does start with fluid now, but still I have adjusted the screw many times and it shows no sign of turning over. I am not sure if there is supposed to be a spring where the screw is, as it will go in all the way to the throttle. I think when you said all the way in, you meant to where the screw is pushed to the spring. I have no spring, and I remember when I had it running, the screw was pretty far turned out. Any ideas?

 

I would buy a new carb, but they are very costly it seems. I do think it is just that pilot screw's position, but I am not sure. I had it screwed pretty far outwards, but it does not seem to want to turn over anymore unless I use fluid, then it dies in ten seconds. I will try to do more fiddling with it tommorow, but any advice would be more than appreciated. If I could just find that one spot I had...

 

The fact that the needle has to be turned out so far tells me that there is a problem with how much fuel is actually reaching the intake. Perhaps those passageways are corroded somewhat, which is blocking the amount of fuel reaching the cylinder. A fine copper wire can often be used as a pipe cleaner to loosen what you can from the oriface. (and yes, there should be a coil spring around the needle). However be warned that those tiny jets can just as easily be plugged up by poking things into them and manually loosening gunk... so I'd be cautious as to how you proceed. Carb cleaner and compressed air are a must. (as are safety glasses) Follow all the steps in your original link... perhaps one of the ports in step 18 is plugged if it was as rusty as you say. Or one of the ball plugs is stuck. Steps 14, 16.

Assuming that you have a crisp blue spark at the plug, I would continue to pursue fuel as your main problem. If the spark is not crisp and hot... if it's orange or yellow at all, you should change the points and condenser, not necessarily the plug. Plugs hardly ever go bad unless they are fouled beyond repair.

 

I want to say that if there was a spring around it, that it would be at about the correct spot to about 1 or 2 turns out. I almost want to say that I cannot find the right spring to go on there. The IPL just shows the screw. It's not a needle end, it gets skinny and then flat. It does have whole in the end though. I do doubt a passageway is blocked, unless it's the ball. I soaked it for a good two days. Then compressed it real well, then let it get an alcohol bath for final cleaning. Any advice on where to look for that spring?

-Thanks, sorry for being long winded. Just want to be as clear as I can.

 

When you say the ball plug is stuck, are they supposed to move? And, I tried to take that bottom piece off of the shorter main jet, but I couldn't pry it, so I just left it alone. I'll see if I can take photos of that screw set up for you tommorow.

 

Your needle should look like the one in the picture in the link. It definitely shouldn't be flat on the tip, or have a ring in the tip... that would show someone screwed it in too far. If it's damaged, replace it... it's cheap. The spring is also an inexpensive part, and while you should have it, it isn't going to help the mower start.

http://outdoorpowerinfo.com/repairs/...low_needle.JPG

What I meant was that the "passageways" behind the ball plugs may be corroded shut. I would also say that if you haven't removed the welch plugs as part of your cleanup, just soaking the carb may not be enough to clean it completely. Welch plugs are ruined once removed an must be replaced. A sharp awl is used to pierce the edge of the plug so that it can then be pryed out. The replacement is tapped in, then sealed with nail polish.

It sounds like it's not picking up fuel to me. By removing the carb from the tank you should be able to check #11 from your link and see whether or not it's picking up fuel. If there is no fuel available, that would explain a lot.

It's pretty hard to work on this problem from 2500 miles away.

 

Here is the side of the carb with the screw, and then there is the screw on the table. I am almost to the point of where, I will see if I can get a new screw and a spring. If that does not work, I will return them and buy a new carb. What do you think Sleeper? Any ideas? I didnt try to start it today as I was busy again. But, I have heard from several people that the screw should have a point and a spring. Also, I have discovered that at the very tip of the screw that it is a hole, and it is holllow I believe.

-Thanks.

 

Huh. never seen a needle like that. It looks like the point is broke off. But you say it's hollow? Strange.

I would look inside the carb to where the needle is supposed to seat. There should just be a small hole where the needle pokes through. Just like in their illustration...

 

Refer to carb diagram at B&S,

Illustrated Parts List

Check out display# 147 part# 691250 in carb diagram. It is called a Jet-Pilot.
This should be screwed all the way in till just snug.
It is not a needle screw.

RR

 

Okay, so I did some more testing and screwed the screw all the way in to almost snug like Rooster said, and here is what is happening. The engine will turn over and IS getting fuel for sure, no fluid or cleaner or anything, just fuel. Here is what happens. The throttle is at nearly dead (valve almost shut) and when i pull start, it will turn over a few times, and if I get it to last long enough, and I open the throttle a bit, it will want to rev up just a bit, and then die. Now, I did make a video of the happening and will have it up in just a bit. It shows the position of the the throttle and everything and I hope it will help in diagnosing my problem. Thanks Sleeper for all your help!

To Rooster, what is the purpose of the "pliot screw" with no needle?

I look forward to your replies!
-Thanks, Charlie.

*Edit* Here is the videohttps://www.youtube.com/watch?v=-fVR...bcApQC8puuuzEg) excuse the brown recluse bite on my hand

 

As old as I am I haven't seen a carb just like yours, but from the parts diagram it appears to be the first jet for fuel control.

You haven't mentioned, but are the valve clearances correct? Should be between 0.004" and 0.008".
Are you getting fuel blowback through carb when it tries to run?
If so you will need to correct the intake valve by grinding it and seat and setting valve clearance.

RR

 

I actually haven't checked the clearances, but since you suggested it, I will take the fuel tank off and check them. I took the head off once and they looked fine to me, moved in sync and all. You really think it's a valve problem by the video? Didn't think it would be that deep of a problem! Heh.

-thanks.

 

Valve clearance is checked at the tappets through the breather cover.

 

I know. Through the PCV box. You guys think it's valves? If it were, wouldn't I be getting lower compression reads? I took it off once and they seemed to move fine, and plus, wouldn't the engine not be able to pull in cleaner and what little gas? Don't mean to question your opinions, or rude, I was just curious.

 

Watched the video. I kinda doubt it has anything to do with valves. Seems to me like every time it almost wants to start, you adjust the throttle and it dies. What happens when you just let it idle without touching anything? Cuz it seems like its just starting to run just fine until you touch it... then it dies.

My first thought might be that the spring is messed up (stretched or improperly connected) that controls the spring governed idle. (part #211 in the link) At :37 in the video, there are some wires all jumbled up in the lower right corner of the picture... assume that's maybe kill switch wiring or something... hopefully not the spring! You could also try opening the choke just a tad instead of reaching to adjust the throttle every time. I often used to open the choke with my finger and put a small screwdriver in there to open the choke just a touch.

OH... and put the air cleaner screw in. Maybe it was my imagination, but when I was fighting with a difficult carb problem, I always thought it would start better with the air cleaner screw in place.

oh, and RR... nice find on the jet-pilot needle!

 

Watched your video again and turned up the volume so I could hear. Sounds like a totally flooded engine. You don't show a lot of the intake, but it appears the choke is staying closed. Can you tie it open with a wire or prop it with a screwdriver and then try it?
I think that carb has an automatic choke. (I will stand corrected on that)

X- Sleeper, I think you are right about the choke!

RR

 

Yeah, I haven't just let it run on it's own yet like that. I'll see what it does tommorow running like that.

Yes! It is the second kill wire. Not sure where it goes. The spring was there, but I removed it because it would bunch up and not kill the engine, only leave it at full throttle.

Nope. It's a manual choke. There's a small notch that comes out the side of the carb that a plastic piece slides on. It has notches. It keeps the choke in a set position instead of just smoothly sliding.

I am not sure if it will start without being choked, but I find out tomorrow. If it starts with choke only, how will i start it and move it while running? And, what is the air cleaner screw? I probably know what you're referring to, just want to be sure.

Thanks you guys for the help!!! You guys are great!!!!

 

When you put the air cleaner on, its the screw that goes down through the choke plate into the neck of the carb. Also not good to run the engine without the air cleaner on anyway. If you're not spraying carb cleaner in the carb, put the air cleaner back on.

I am guessing you just need to find the "sweet spot" where the choke lever needs to be set (for starting) in order to partially choke it... (maybe not fully choked) so that it will give you a little more time to let go of the pull cord, and get around to the controls where you can then adjust the choke (opening it up once the engine has run a few seconds) and then increase the throttle with the levers. Once you learn the best position where the levers need to be at startup, I think you will have an easier time with it. Those older motors were sometimes fussy.

Generally you have to open the choke pretty quickly in order to increase rpms with the throttle. Giving it more gas while it's fully choked (like you were doing manually in the video) will often just kill the engine.

So let's say you have it at 3/4 fully choked and half throttle... and it starts to putt-putt-putt. Leave it alone for a few seconds and then slowly open the choke. It should start to smooth out without touching the throttle at all. When the engine is fully warmed up, the choke should be wide open. You really only need to choke it when the engine is cold. (initial startup)

that's probably part of the problem then. The spring doesn't have anything to do with the kill switch. The position of the throttle cable (which is adjustable) is what adjusts the kill switch at full stop.

 

Okay, okay. I only have the air cleaner off because that is the only way to adjust the throttle, turning the throttle plate on top of the carb. If I can get it to run, I always try to run my engines with the air cleaner on at all times.

Yes, the spring was there, it connected to the throttle panel on the side of the panel, when you put more throttle, the spring would pull back on the plate, allowing for more fuel, thus more power. When you put the throttle on lower RPM's, it would turn downwards and bunch up, and would not push the throttle plate to a lower throttle setting. So, I just took it off, and really am contemplating replacing it for full functionality.

I will try the choke method you guys talked about as soon as I get a chance tomorrow. Is it an absolute must to have that stop underneath the choke? It only gives me five positions or so to have the choke in, so not much to choose from.

-Thanks!

 

Why? Is something wrong with the throttle lever cable?

It sounds like you need to put it completely back together the way it's supposed to be... spring and all... and start it up!

The spring I'm talking about connects the throttle to the governor. Changing the throttle should not cause the spring to do anything unusual. If it does, the spring is either damaged (bent or stretched) or it has been hooked up improperly.

 

The governor spring is stretched I think. It's got a spring with a hook on one end and a really long straight end with a hook. On top of the throttle plate, there's a metal piece that loops half way, just before or goes into the starter housing, the spring connects from the throttle panel piece (to control the throttle) into that loop and moves it according to the throttle selected on the planet. It'll get it to almost full throttle, but it won't push it back to closed. it pushes itself down and gets stuck.

Now, after that loop, the metal rod goes into the housing and hooks onto a piece of plastic that hangs itself above the flywheel. It's hard to explain but I'll do my best.

On the magneto, there is a the left hand side screw mounting hole. Also there is the mounting plate for piece. And, I goes from just to the top of the flywheel to the top of the housing just about. I almost want to say that if the flywheel is spinning fast enough, it pulls the throttle to a closed position (air from the wheel catches on the piece). But I really don't know what purpose it serves. If I move it with my hand, the metal rod pulls and opens the throttle.

 

You've pretty much described it correctly. The plastic part is an air vane. It basically helps tell the engine how fast it's running based on the air speed created by the fins on the flywheel. That, along with the governor help partially control the throttle, preventing it from running out of control. The air vane and the governor act together to slow the throttle down and prevent the engine from surging too fast.

If your springs or linkages to those parts are screwed up, I would highly suggest replacing them, but sometimes the way they hook up is like a puzzle, and there is only ONE RIGHT WAY for them to be connected. If they are hooked up wrong, it will usually result in problems.