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Briggs and Stratton 5 hp (Model 130902) Jet Pulse carburetor problems... Any ideas?

#1

balooba

balooba

Hello everybody!

I need some help or advice with my Briggs and Stratton 5 hp (Model 130902).
Tje problem seems to be with the Jet Pulse Carburetor.
Very simple, but I'm lost!

carburetor.png

I can get it run but only without the airfilter – or more specific, without the screw in the middle of the carburetor's air intake (where the choke is).
Any idea what I should do, adjust or check? How should I proceed?

All ideas are welcome.
Thank you in advance!


#2

sgkent

sgkent

If you put the screw back in without the air filter, it dies?
It looks pretty dirty inside. Have you tried spraying some Berryman's B12 carb cleaner in it WHILE it is running to clean out some of the carbon build up around the butterfly etc..


#3

R

Rivets

Not a real difficult fix. My advice would be to re move the carb and give it a good cleaning. Replace the pump diaphragm and the carb to tank gasket.


#4

balooba

balooba

sgkent said:
If you put the screw back in without the air filter, it dies?
It looks pretty dirty inside. Have you tried spraying some Berryman's B12 carb cleaner in it WHILE it is running to clean out some of the carbon build up around the butterfly etc..
Click to expand...
Yes, exactly. If I put the screw back, it stops the engine.
Okay, good advices, thanks to all. I'll remove the carburetor, clean it (and study)...
I'll try that Berryman's B12 carb cleaner, too.
Let's see how it goes!


#5

F

Forest#2

Just a heads up about your carb.
You might should re-search parts and even replacement carb first.

Some of them are NLA and you can be playing with a dinosaur egg.

I like to know such before I flog into old carbs. If I know before hand I proceed more cautious.
We do not have the code # from your engine, but some of them replacement carbs appear to fit but the bolt pattern is not one size fits all.
AND
make sure the brace bolt off the bottom of the gas tank to the block is secured good or one of the cast pot metal ears WIIL BREAK OFF the carb eventually.


#6

sgkent

sgkent

when I went into my local mower shop they had two part numbers that superseded most of those carbs. The original number was NLA but the part they had to replace it worked fine. I could not duplicate their briggs number replacement online so I have no idea how they came to the conclusion which fits which, or where they came up with the part number. The guy looked at it, someone else looked at it and they said something like, "yeah that is the XYZ and not the ABC because of this." Their part worked fine.

Does the bolt interfere to keep the butterfly from moving?


#7

R

Rivets

Depending on the type and code numbers, there are two different carbs used on that model engine
#299488. NLA
#396748. Approximately $72.00
i know the diaphragm and gasket are available.


#8

balooba

balooba

Thank for all the info. I have now removed the carburetor-tank-combo to my ”laboratory” for more detailed inspection. My plan is to first try some clean up and non-destructive studying...

The engine is labeled:
Briggs & Stratton 5hp
Model 130902
Type 1237 01
Code 90021407

I have seen pretty similar Jet Pulse carburetors for sale. If all fails, the B-plan is to replace the whole engine to this mower.

All hints and advice are welcome and much appreciated.


#9

S

SmallEngineHead160

I would start by cleaning up the carburetor
And replacing the diaphragm.
98% of the time an old diaphragm is cause of problems on these.


#10

S

SmallEngineHead160

So here's part number info that maybe helpful to you or others reading.
Carburetor:
299448 (used on engines made before date code 83110800)
396748 (used on engines made after date code 83110800)
Carburetor diaphragm:
270026
Carburetor base gasket (carb fuel tank mating gasket) 270073
Carburetor kit: 494625 (includes pump diaphragm base gasket fuel mixture jet screw carb to intake gasket and pretty much what else you need for a complete carb rebuild.
I personally would checkout mfgsupply.com as they have pretty much have the best prices on these parts.
These part numbers as well as others for individual parts for these carburetors can be found on Briggs and stratton.com site
Or other parts sites that have a parts lookup tool.


#11

S

SmallEngineHead160

I also should ad that these pulsa-jet carburetors are pretty simple to work on.
The two main bad problems I have found with them are the throttle shaft bushings wearing out and the carb base warping.
A slight warp may or may not be a problem.
Just depends on if it's warped bad enough for the gasket not to seal.


#12

balooba

balooba

Thank you for all the great advices.
mfgsupply.com is a gold mine, thanks!

SmallEngineHead160 said:
... two main bad problems I have found with them are the throttle shaft bushings wearing out and the carb base warping...
Click to expand...
Okay, I think my carburetor's throttle shaft bushings are more or less loose. Is there anything I can do?

About the ”carb base warping”, I'm not sure where to look.
This carburetor is quite simple...

I tried to inspect the carburetor very closely. Could not really see anything obviously wrong. No lack of fuel. Not especially dirty. Nothing seemed to be broken. I cleaned it (after the photos) but did not open it yet.

Before opening and more cleaning, should I some extra precautions?
For example, how about the adjustement screw, should I remember how much it's screwed?

Here some photos.

IMG_4640.JPG

IMG_4637.JPG

IMG_4638.JPG


#13

F

Forest#2

You asked this:
For example, how about the adjustement screw, should I remember how much it's screwed?

Usually around 1 1/2 turns out from a light CW setting. (and this setting is critical on some. (1/8 turn off can result in non-smooth engine performance on some)
It's quite common as the carb diaphragm ages the adjustment screw setting can change and the engine will not run smooth at high rpms and the setting may even change little bit after the engine has run for awhile or as the engine warms up. A new diaphragm will sometimes correct such.
I'm talking about the diaphragm with the flapper valves as it gets old and ages causing the jet adjustment to change. sometimes just 1/8 turn will get it smooth for awhile. I try to keep spare diaphragms in stock and can replace them with the pulsa-jet in place.
Be cautious of all the screws, also the tank screws and do not overtighten and strip the threads.
I've heard of using two carb to tank base gaskets if the top of the tank is warped, but I've never had to do such.


Here is a link that does not exactly match your pulsa-jet but will give you some good ideas about such working on them, just slect Briggs carbs and scroll down to Pulsa jet, tank mounted carbs.

https://outdoorpowerinfo.com/repairs/


#14

S

SmallEngineHead160

balooba said:
I think my carburetor's throttle shaft bushings are more or less loose. Is there anything I can do?

About the ”carb base warping”, I'm not sure where to look.
Click to expand...
If the throttle shaft is just a little loose it may be fine it just depends on how loose it is.
When they get badly worn the engine will start sucking air through the worn shaft/bushings and start messing up the air fuel mixture going into the engine.
There really is not a practical way to fix it unless you where to ream and install new bushings but I have never really seen anyone do that on these though I'm sure it's possible.
It's something I'm gonna experiment with one day.
But for now I really wouldn't worry about it for the moment until you get that pump diaphragm replaced as more than likely that is your problem.

As for the carb base I will take some pictures and post to show you were to look but judging by your pictures of your carb it seems to look pretty good.


#15

S

SmallEngineHead160

Gonna try posting pictures for the second time...
looking at carb base notice left and right corners are warped down slightly from center mainly the left side.
this can cause a uneven sealing surface on the fuel tank.
Again, judging by your pictures of your carburetor I don't think you'll have a problem.IMG_20230709_084132629.jpgIMG_20230709_084154491.jpg


#16

S

SmallEngineHead160

I made a quick video overviewing the basics of these carburetors not a very detailed video but hope it may help.


#17

balooba

balooba

SmallEngineHead160 said:
I made a quick video overviewing the basics of these carburetors not a very detailed video but hope it may help.
Click to expand...
Very good video, thank you very much. (y)


#18

S

SmallEngineHead160

Your welcome!


#19

D

DStahl

balooba said:
Hello everybody!

I need some help or advice with my Briggs and Stratton 5 hp (Model 130902).
Tje problem seems to be with the Jet Pulse Carburetor.
Very simple, but I'm lost!

View attachment 65692

I can get it run but only without the airfilter – or more specific, without the screw in the middle of the carburetor's air intake (where the choke is).
Any idea what I should do, adjust or check? How should I proceed?

All ideas are welcome.
Thank you in advance!
Click to expand...
Whenever I try to clean or rebuild the carb. on any small engine, and it does not run correctly, I jump on ebay and buy a new one for $15. It saves you time and money. Don't throw away your old one though; you can use it for parts one day!


#20

J

Johner

balooba said:
Hello everybody!

I need some help or advice with my Briggs and Stratton 5 hp (Model 130902).
Tje problem seems to be with the Jet Pulse Carburetor.
Very simple, but I'm lost!

View attachment 65692

I can get it run but only without the airfilter – or more specific, without the screw in the middle of the carburetor's air intake (where the choke is).
Any idea what I should do, adjust or check? How should I proceed?

All ideas are welcome.
Thank you in advance!
Click to expand...
Buy a new filter.


#21

M

moparjoe

balooba said:
Hello everybody!

I need some help or advice with my Briggs and Stratton 5 hp (Model 130902).
Tje problem seems to be with the Jet Pulse Carburetor.
Very simple, but I'm lost!

View attachment 65692

I can get it run but only without the airfilter – or more specific, without the screw in the middle of the carburetor's air intake (where the choke is).
Any idea what I should do, adjust or check? How should I proceed?

All ideas are welcome.
Thank you in advance!
Click to expand...
I agree with Rivets, a good cleaning and replace pump diaphragm


#22

Its Me

Its Me

balooba, worked on them for years they are the best carburetor and are trouble free most of the time, just clean it and, pull the main jet them took inside where the jet come from and remove the insert ,it is brass the, the rubber pulses and picks up gas through the long up the gas in puts it in the small well and the piston suction pulls the gas into the engine, for a smooth and great running a trick is to get a 12" file put it in the vise, take the rectangular plate that covers the diaphragm and push it along the file length wise, make on or two passes them look at the cover you will be surprised how warped it is, run it down the file until all the warp is gone, it will run perfect, I loved working on those old engines, be a mechanic fix it don't be a parts changer, there is not much satisfaction in being a parts changer, Joe​



#23

The Maintenance Guy

The Maintenance Guy

balooba said:
Hello everybody!

I need some help or advice with my Briggs and Stratton 5 hp (Model 130902).
Tje problem seems to be with the Jet Pulse Carburetor.
Very simple, but I'm lost!

View attachment 65692

I can get it run but only without the airfilter – or more specific, without the screw in the middle of the carburetor's air intake (where the choke is).
Any idea what I should do, adjust or check? How should I proceed?

All ideas are welcome.
Thank you in advance!
Click to expand...
If it's one of those all plastic things, just replace it. They're cheap enough.


#24

F

first pull

balooba said:
Hello everybody!

I need some help or advice with my Briggs and Stratton 5 hp (Model 130902).
Tje problem seems to be with the Jet Pulse Carburetor.
Very simple, but I'm lost!

View attachment 65692

I can get it run but only without the airfilter – or more specific, without the screw in the middle of the carburetor's air intake (where the choke is).
Any idea what I should do, adjust or check? How should I proceed?

All ideas are welcome.
Thank you in when you clean the carburetor don't forget the pickup tube in the tank,that will give your symptoms too
Click to expand...


#25

T

TobyU

Pretty much the given for any one of these that doesn't run properly is to remove the tank and take the carburetor off the gas tank, get the tank empty and all the crap out of it cuz they will be plenty, then put a new gasket and diaphragm between the carb and the gas tank.
That fixes the problems 95% of the time.
There is a jet underneath the screen like sock that you can slightly rotate and pull off and then pop out the plastic jet tube with a small screwdriver then you can run wires through these and blow them out and everything else but most the time that's really not necessary.

More than likely the reason this one wasn't running in the first place on its own is because the diaphragm and the spring action wasn't sucking a fuel up to pump it and that whole pulsa fashion.
With the screw out at least at the tank's pretty full, it gets enough fuel and sucks a little bit up there to stay running at least somewhat.

That diaphragm always gets brittle and and stiff over the years and just won't flex like it should..

These were great Little engines back in the day and this style with the primer bulb is much better than the older styles with the chokes or the autochoke etc and I kind of liked them back then because they were more forgiving than the the tecumseh with the float bowl carburetor which often had to be cleaned out every year to make it run right but honestly, today, I would rather have the next upgraded Briggs & Stratton with the float bowl carburetor.
They just seem to be much longer lived and they're built a little bit better and they have a little more horsepower too. Parts are so readily available and cheap.

BTW you don't have to buy the Briggs & Stratton brand for that diaphragm and gasket. Several aftermarket companies make them and they are even available at O'Reilly Auto Parts in advance Auto Parts hanging up in a little blister pack with their lawn mower stuff or sometimes it's in the back but they do carry it however I can't recommend buying it from them now!
It used to be under $4 and all was right with the world but now it's almost 9.00 so I will never buy another one from them.
I can get a five pack on eBay for that kind of money.

Places are going to realize, at least when dealing with me, that when you push that hard ...I'm gone.
I might give you a dollar more for it then I can get it online just because I want to have its day but the older I get the more patient I have become and I will wait for anything to say 50 cents.


#26

P

pbsmower

balooba said:
Hello everybody!

I need some help or advice with my Briggs and Stratton 5 hp (Model 130902).
Tje problem seems to be with the Jet Pulse Carburetor.
Very simple, but I'm lost!

View attachment 65692

I can get it run but only without the airfilter – or more specific, without the screw in the middle of the carburetor's air intake (where the choke is).
Any idea what I should do, adjust or check? How should I proceed?

All ideas are welcome.
Thank you in advance!
Click to expand...
You might check to make sure a good gasket is in place. If there’s no gasket, a poor seal will cause a problem. If there is a thin old gasket, try adding a thicker one to raise the air filter as well as improving the seal.


#27

T

TobyU

pbsmower said:
You might check to make sure a good gasket is in place. If there’s no gasket, a poor seal will cause a problem. If there is a thin old gasket, try adding a thicker one to raise the air filter as well as improving the seal.
Click to expand...
I've never seen one of those gaskets make a bit of difference in the way one of these things runs. It's only there to prevent some dirt from bypass the filter but even that's kind of a moot point on one of these with its foam filter etc.
People run these things for decades without even having an air filter on them and they run just fine.


#28

S

sharnett

balooba said:
Hello everybody!

I need some help or advice with my Briggs and Stratton 5 hp (Model 130902).
Tje problem seems to be with the Jet Pulse Carburetor.
Very simple, but I'm lost!

View attachment 65692

I can get it run but only without the airfilter – or more specific, without the screw in the middle of the carburetor's air intake (where the choke is).
Any idea what I should do, adjust or check? How should I proceed?

All ideas are welcome.
Thank you in advance!
Click to expand...
I have an old Briggs with a vacuum ("automatic") choke. Briggs had some great ideas but the vacuum choke wasn't one. On my engine, the air cleaner screw is the stop for the choke. Without it, the choke butterfly goes over-center and becomes a choke again. If yours is designed like that, it would indicate that your engine runs very lean and needs the choke to run. Long story short, as many others have said, clean and rebuild the carb.


#29

Helvehammer

Helvehammer

balooba said:
Hello everybody!

I need some help or advice with my Briggs and Stratton 5 hp (Model 130902).
Tje problem seems to be with the Jet Pulse Carburetor.
Very simple, but I'm lost!

View attachment 65692

I can get it run but only without the airfilter – or more specific, without the screw in the middle of the carburetor's air intake (where the choke is).
Any idea what I should do, adjust or check? How should I proceed?

All ideas are welcome.
Thank you in advance!
Click to expand...
Egads no exaggeration I must have a couple thousand 130902-repairs under my belt 1971-2009. Pretty sure you have the problem backwards - the only fuel it is getting is through the not-metered fuel leaking through the AF screw hole - put the screw in and no fuel at all and it dies.
If you can get a copy of the BS Repair instructions dated 1963 - just follow them in scope and detail.
Probably you can't even on Ebay so I will take it from the top:
Make sure carb throttle blade and choke are open and the spark plug is in it. Snug down the three head bolts surrounding the exhaust valve. Remove the fan housing and recoil starter. put the spark plug wire in the provided V-safety-notch. watch your fingers while you flip the flywheel backwards and it should bounce off compression and go forward a little bit. This duplicates the power stroke of the engine. It is a form of leakdown test. The reason you can't do the same test going forward is the Easy Spin automatic compression release cracks the intake valve open about .010" beginning about an inch before TDC on the compression stroke. The intake shuts completely right before the mag fires. Cam timing one gear tooth off screws this up - it's got to be on the marks.
If it bounces real good you can get fancy and turn it very slowly backwards and listen to the exhaust outlet, carb inlet and head gasket. The piston rings normally leak a very small amount - that's fine.
Okay pull the plug out and figure out how to hold the end of the wire 5mm/.200" off the cyl head anywhere (paint doesnt matter) and spin it over with a drill at least 150 rpm and it should snap a spark (forget color) every single time for at least a couple hundred revolutions. It if ever misses any = fix it (new points usually). Reassemble it all like you are going to run it with a brand new non-Champion, non-China spark plug gapped .030"
Remove every bit of fuel out of the carb and tank. Every last drop, not even moist = DRY.
Make sure it's full-to-overflowing with clean SAE 30 heavy duty motor oil. The ultimate best is Aeroshell "Oil W" SAE 30 (Aviation Grade 60) bar none. Your engine has aluminum cylinder walls which love to score and wad up on the rings - if yours passed leakdown it doesn't have that. It's important because IT IS GOING TO RUN.
Bolt clamp the thing down to something solid. Get a little 2-cycle plastic bottle in the 8-20oz size range that has a good cap. Clean it out good and fill it with 32-1 (or thereabouts) FRESH Two-cycle fuel-oil mix. 50-1 won't work. Richer than about 16-1 is hard on spark plugs. Poke a 1/16" hole in the lid from inside going out with an icepick or something. Don't drill it.
You bolt it down because 1) You are going to set the governed speed to max without any choking action.It has to stay set at that point. Use a stiff throttle control or something.
2) You are going to squirt less than a tablespoon of fuel in the carb throat then set bottle down.
3) Get two fingers on the actual throttle butterfly shaft and be prepared to take control of it either to keep it from overspeeding past 3600 rpm or to keep it from slamming shut onto the idle stop screw (the governors on these things are flaky - letting overspeed even once will throw the governor weights off an tangle around inside the engine)
4) Stroke the rope once good it will start and should govern itself if you let go the throttle.
5) Soon as you can after you crank it grab up the squirt bottle and give it another little squirt, then another - then finally try to keep it running with a steady tiny stream of fuel.
6)Now try and slow it down with the throttle while keeping it running with a tiny tiny stream of fuel. It's a lot easier if you make the gas cap hole so small you have to squeeze hard to make it run full speed. Really about 1/32nd hole is best for this whole test. The reason to do this is to bypass the usually-leaky crummy carb-block gasket and the carburetor's fuel metering ability. Think of it as the final test to establish "if this thing got the right amount of fuel and had no induction air leaks - then it really would run right."
It's getting late - I will go into how to force one these crummy "no fuel emulsion air bleed" carbs to work right tomorrow night. But you are going see if all that is necessary next...
7) Get an RELIABLE assistant to help you for the next part.
8) Start it as before, get it running under direct control of the throttle while bottle feeding it, make it run at an idle (WITH THE AIR FILTER SCREW IN IT) and have your assistant begin adding fuel to the tank in the safest possible way. HAVE A CO2 FIRE BOTTLE OR TWO RIGHT NEXT TO BOTH OF YOU. If you get it to pick up fuel (so that you can quit squirting fuel in it and it runs by itself with the jet open 2.5 turns) but the tank has to be all the way full-to-overflowing for that to happen it means that at least the small fuel pickup is clear and the carb-to-block gasket isn't leaking air real badly. It also means that the problem is with the system that normally fills the little mini-tank the small pickup slurps fuel out of = the long fuel pickup, or the induction-pulsation operated diaphragm fuel pump.
More tomorrow...


#30

L

LMPPLUS

balooba said:
Hello everybody!

I need some help or advice with my Briggs and Stratton 5 hp (Model 130902).
Tje problem seems to be with the Jet Pulse Carburetor.
Very simple, but I'm lost!

View attachment 65692

I can get it run but only without the airfilter – or more specific, without the screw in the middle of the carburetor's air intake (where the choke is).
Any idea what I should do, adjust or check? How should I proceed?

All ideas are welcome.
Thank you in advance!
Click to expand...
Have you replaced the fuel pump gasket and diaphrgam ?


#31

S

slomo

sgkent said:
It looks pretty dirty inside. Have you tried spraying some Berryman's B12 carb cleaner in it WHILE it is running to clean out some of the carbon build up around the butterfly etc.
Click to expand...
All that would do is wash all that grit and grime into the engine straight to the rings. Better to pull the carb and clean it proper.

Tank needs to be spotless or you will have problems. As you can tell right now. You have a dirt issue.

Agree with the others, will need a carb rebuild or a new Chinese E-Pray carb. Pretty sure that carb is no longer made. Double check me on that.


#32

S

slomo

Also look for a hairline crack in the long plastic fuel pick up tube. There is a fix for that if needed.

Make sure you have a new good rubber boot on the pulse line. Most are loose and will cause a poor pulse from the engine if it leaks.

You can lap the carb base and the manifold where it attaches to the block. Those are must do's.

The Briggs gasket for the manifold to the block is about 3/8" thick as in super thick. They are double the size of the Chinese carb and gaskets you can get of Scamazon or E-Pray. So if you buy a Chinese and use the block gasket, might have a vacuum leak.


#33

S

slomo

OP, do everything you can to keep that old OEM carb running. Yours has an adjustable needle for the fuel mixture. New Chinese carbs do not have that screw.


#34

T

TobyU

Upon closer examination of the picture I realize this is a true carburetor but not the most common style that you see on Briggs most of the time. The most common style I've run into is on the horizontal crankshaft engines which is the longer tubular style or maybe it's just the gas tank itself that's throwing off my recollection.
Most of the Briggs engines that look like this and have this style gas tank have the diaphragm and gasket style carb which is the larger diaphragm and not the little one that goes in the side like in this pulse jet.
I never have really liked this style but it does okay on the other engines but I much prefer the newer little small horsepower vertical shaft engines like these that have the metal gas tank the plastic carburetor and the primer bulb.
I guess the ultimate would be to have aluminum and a prime bulb so you wouldn't have the warpage issues that sometimes occur but rarely is there really any problem with the plastic ones so I could deal with that.
The primer bulb is so much nicer than having to deal with a choke and those don't have a mixture screw and I'm good with that too because once you put her new diaphragm and gasket in them and if they're clean, they always run just fine.
They are not my favorite Briggs engine though as I would much rather have the larger or upgraded one with the float bowl carburetor but still with an L head. I just really don't like the older, considered upgraded, Briggs & Stratton overhead valve engines because they're just more to go wrong, and it does, and the head gasket is blue easier and more often.
The old L heads just last and last and last and I hardly ever even have to worry about valves or valve adjustment.
It's nice to be able to just pull a head off quickly and fix things on it versus the seats being in the block and the valves having the annoying side access with the gasket that always breaks. Lol


#35

JoeZ

JoeZ

balooba said:
Hello everybody!

I need some help or advice with my Briggs and Stratton 5 hp (Model 130902).
Tje problem seems to be with the Jet Pulse Carburetor.
Very simple, but I'm lost!

View attachment 65692

I can get it run but only without the airfilter – or more specific, without the screw in the middle of the carburetor's air intake (where the choke is).
Any idea what I should do, adjust or check? How should I proceed?

All ideas are welcome.
Thank you in advance!
Click to expand...
This is my affiliate link.
Once you're in there paste in
Hipa Carburetor Kit For #498298 692784 495951 492611 Briggs Stratton 112202 112232 134202 137202 133212 5HP Engine

$21.98
Let me know if this was of help.


#36

balooba

balooba

TobyU said:
off my recollection.
Most of the Briggs engines that look like th
Click to expand...


#37

balooba

balooba

I ordered the Carburetor Kit for Briggs & Stratton from MSG Supply.
Super fast delivery, thanks!
(It took almost a month from my local post office to deliver the kit...)

I managed to replace all the gaskets and parts, I also carefully inspected the carburetor.
Looks clean and good. It also works.
Thank you all for all the help and advice.:)

But, I have a problem, for some reason the engine works but only if I adjust and control it manually almost non-stop.
I get it started and run pretty good. On idle or higher rpm but the engine stops easily in some situations.
Obviously the fuel works, ignition and no mechanical faults. It has to be something with some adjustements...

Where is the problem?
- governor setup?
- fuel-air-mix adjust?
- something else?

What should I check and how?
Let me know some ideas and how I should proceed with the adjustements.
Thanks in advance!

IMG_5031.JPG

IMG_5035.JPG


#38

S

SmallEngineHead160

So a few questions: first off I'm not sure if I just can't remember or it was never stated
But what type of equipment is this engine powering I'm assuming it's a mower?
I apologize if it's stated already on this thread
I looked back over most of the thread but just couldn't find it.

Have you adjusted the mixture screw at all since carb rebuild?
Regular procedure would be one and a half turns out from fully seated, get the engine started then start turning the screw slowly one direction then the other untill the engine smooths out.
Fine tuning should be done with the engine warmed up to operating temperature.
Slowly turn the screw till the engine starts to run rough then turn it back opposite direction past the spot where it ran smooth until it runs rough again. Turn it back and find the sweet spot where it runs the smoothest inbetween sometimes you may want to repeat the process a couple times.

I would also check your governor linkege and spring make sure everything moves freely and is installed correctly.


#39

balooba

balooba

SmallEngineHead160 said:
So a few questions: first off I'm not sure if I just can't remember or it was never stated
But what type of equipment is this engine powering I'm assuming it's a mower?
Click to expand...
Yes, it's powering a mower, Murray 5/25.



SmallEngineHead160 said:
Have you adjusted the mixture screw at all since carb rebuild?
Click to expand...
Yes I have. I have to tried do that very systematically and carefully.
I get the motor started, it will run. Both idle, low and high rpm, there is power. BUT, only if I manually ”manage” and control it. That means, I keep an eye on and adjust the throttle etc.
(my plan is to do a short video that would explain this more clearly)



SmallEngineHead160 said:
Regular procedure would be one and a half turns out from fully seated, get the engine started then start turning the screw slowly one direction then the other untill the engine smooths out.
Fine tuning should be done with the engine warmed up to operating temperature.
Slowly turn the screw till the engine starts to run rough then turn it back opposite direction past the spot where it ran smooth until it runs rough again. Turn it back and find the sweet spot where it runs the smoothest inbetween sometimes you may want to repeat the process a couple times.
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I will try to follow those instructions in detail. Funny is that this carburetor has only this one screw and still it's so complicated to me, ha haa.


SmallEngineHead160 said:
I would also check your governor linkege and spring make sure everything moves freely and is installed correctly.
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Good idea, thanks. I try to take some photos and upload here. Maybe some specialist could tell that the assembly is correct.

Thank you for the tips and advice!

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#40

S

SmallEngineHead160

Everything thing looks correct
The spring you are questioning just sticks in the hole with the spoke/linkege on the throttle shaft. I'm not really sure what it's for I just know they always seem to pop out of place.

Your governor spring looks fine, but sometimes they can get stretched, however it looks like it's pulling the throttle shaft all the way open in the fast position so it may be fine
But the only way to know is by checking the engine RPM. Which of course you would either need a tachometer or a trained ear to know what speed your running at.

So by managing the speed manually do you mean with the throttle control on the mower?
I just wanted to clarify.

If you could make a video I think that would help a lot


#41

Its Me

Its Me

balooba, I had one many years ago that was giving me much same problems that you are having, it would run farily good but when you moved it just the slightest bit it would start running terrible, similar to flooding, what I found was that they person that owned it had removed the rubber bushing that is on the top of the carburetor and when he put the filter back on did not put it and tightened the air breather screw so tight to hold the filter housing on that he pushed the hole where the threads are so deep that it cracked a hole in the top of the tank, that is a blind hold, meaning where the threads stop is where the hole ends, not open into the tank, that very well could be a lot of your problems, nothing worse that something so simple as those can get so complex, good luck, Joe​



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