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View Full Version : Briggs and Stratton carb help?


dbsound
04-23-2008, 02:32 PM
So, I've got a Briggs and Stratton 3.5 classic(yes, I know they're not great, but it's for a rental property, so you can't let renters tear up a good mower). Anyway, it won't run. It's only about 6 months old, and probably only has about 10 hours on it. I've changed the carbuerator gasket(which go bad on the Classic, ALOT), and there was no change. Dumped all the gas, and put fresh in. Nothing. It WILL prime and start, but won't feed itself after the prime start. If I keep hitting the primer button, it will stay running, as long as you pump it. Everything still looks new on the whole engine.

Why won't it feed itself?
THANKS SO MUCH for your input.
David

jkason
04-23-2008, 04:02 PM
Did you change the carb gasket or the diaphragm AND gasket?

If you changed both, I would suspect a warped mounting surface. Only remedy is replacement. (Under warranty, of course.)

dbsound
04-23-2008, 04:44 PM
That's the double gasket kit, right(thin one, and a thicker one). If so, yeah, I replaced both. It's like it's just not drawing gas into the carb.:cry::cry::cry:

Restrorob
04-23-2008, 09:04 PM
Did you remove the screen from the bottom of the carb and spray carb & choke cleaner through the port in the center ? What about the screen in the bottom of the long white fuel pick up tube, Did that get cleaned ?

dbsound
04-24-2008, 03:07 AM
I blew through it. I'll try a better cleaning of it, tomorrow.
THANKS so much.

LawnVet
04-24-2008, 11:39 AM
Does the carb have electrical wires coming out of the bottom? If so it could be the, unnecessary, anti-backfire device. You can bi-pass that if it is the problem.

dbsound
04-24-2008, 01:56 PM
No. No wires.

dbsound
04-25-2008, 07:55 PM
So can someone explain to me - after it's primed, how does it draw the gas?
Up the long tube?
What's the other smaller tube, with the cylindrical screen on it?
What makes it draw the gas?

This damned thing has SO FEW hours on it, I can't figure out why it won't stay running.

rclopez1118
04-27-2008, 10:03 AM
Your problem is the carb, and needs to be cleaned very well. make sure every small hole is clean, and the diaph kit is installed in the right order. oh yeah,..make sure the primer bulb is working right too.

Restrorob
04-27-2008, 10:55 AM
Post the model and type numbers off the top cover above the spark plug so I can see exactly which carb you have.

dbsound
04-27-2008, 02:47 PM
Model 9J902 0559

THANKS!

Restrorob
04-27-2008, 04:28 PM
OK David,

We have a pretty picture here to help.

The diaphragm is a fuel pump, The fuel is pulled up the pick-up tube then through a port in the carb where it's directed to the little cup in the top of the fuel tank.

Then the main jet submerged in this cup full of fuel pulls the required amount of fuel up into the carb making the engine run properly.

Make sure the pick-up tube screen is open and make sure the main jet is open (plastic) then check for a small vent hole in the tank noted. Some has this vent and some doesn't, If your's does make sure it's open with a bristol from a hand wire brush.

Make sure the diaphragm and gasket are installed as shown with the spring and they didn't move out of position when installed as another poster mentioned.

After doing all this and the engine still won't run a new carb with a new diaphragm only cost 23 bux.



http://i107.photobucket.com/albums/m314/Restrorob/Briggs/L%20Singles/BriggsPlasticCarbClean.jpg



Good Luck

dbsound
04-27-2008, 07:40 PM
Grrr. EVERYTHING is clean as a whistle. Like I said, this thing doesn't have 8-10 hours on it. It just won't draw gas. I give up.
Can you give me a link to the $23 carb?
Thanks SO much for your input. I really appreciate it!:)

StevieZ
04-28-2008, 11:31 AM
On those low end classics, I've found its easier to replace the carb, I keep a few known good ones around just for that purpose. I don't see them like I used too. Good luck.

Restrorob
04-28-2008, 01:07 PM
Just click the below link then add to cart to purchase.....


http://www.briggsandstratton.com/maint_repair/repair_parts/index.aspx?_dp=1&pno=498811


Cya

dbsound
04-28-2008, 01:20 PM
Thanks, buddy!

Restrorob
04-28-2008, 07:33 PM
No problem Dave.....http://www.xtremesystems.org/forums/images/smilies/thumbsup.gif

skynyrdfan
05-11-2008, 07:52 AM
I have the exact problem with a Poulan push mower, same B ad S carb. If I prime it, itll burn up that gas then stall. If you keep squirting gas in it with the primer bulb it will still run. Thats a great diagram of the carb. Im just wondering weather to rebuild it, or replace. Its only 3 years old old has never started on the recommended 3 primes, always had to push it 5 or6 times even since new. Advice anyone? Thank you. Great site. Doug in Pa.

StevieZ
05-11-2008, 01:13 PM
To me, for $23 throw it away and get a new one, It will save you time and frustration.

themow
05-11-2008, 09:20 PM
this was happening to me last week....I got a new diaphran and gasket and sprayed carb and choke cleaner in the jet and the pickup and put it back together and now its fine. ... These things need more than 3 pumps to get goin sometimes 5 or 6....guess theyre just that way

dutch1
05-12-2008, 04:41 PM
Sounds like you replaced the diagphram and gasket(Briggs #495770)--- diagphram on the tank first then the gasket followed by the carb. Make sure the pickup tube is clear, then remove the screem on the bottom of the main jet. Find a small wire that will pass through the main jet then blow out with carb/choke cleaner followed by air. This will normally correct any running problems unless you have inadequate compression. If there is not good compression there will not be adequate vacuum in the cylinder on the down stroke to operate the diagphram(pump fuel).

Dutch

skynyrdfan
05-25-2008, 05:50 AM
I got the new carb and put it in. It still only runs what you prime in it then quits. I tied a string to the handle to keep it running and got down and looked, and while there is nothing binding on the gas linkage,it doesnt move itself to give it gas. I tied a small piece of wire from the linkage to the tank to hold it open so it runs now. But what in the world could be wrong?

themow
05-25-2008, 11:40 AM
what gas linkage are you talking about???
Do you mean the throttle linkage

dutch1
05-25-2008, 11:44 PM
If you have to tie the linkage from the air vane governor-carb linkage to keep it running, is it possible that the governor spring is unhooked or missing?

skynyrdfan
05-26-2008, 06:57 AM
Yes. On the top of the carb, is a long link that goes down the side of the motor which is hooked to something under the cover on the handle side. I thought it seems like there should be something else there. Does anyone have a diagram, possibly showing whats missing and where it goes? Thank you.

skynyrdfan
05-26-2008, 07:07 AM
Plus, I dont think there is another hole on the linkage thing on the top of the carb for another spring to go to, but Ill have to lok again

themow
05-26-2008, 06:37 PM
If you posted a picture, we could see what youre talking about....

take a look at the third picture on this post and tell me if it looks the same

thezaz
05-26-2008, 07:02 PM
So, I've got a Briggs and Stratton 3.5 classic(yes, I know they're not great, but it's for a rental property, so you can't let renters tear up a good mower). Anyway, it won't run. It's only about 6 months old, and probably only has about 10 hours on it. I've changed the carbuerator gasket(which go bad on the Classic, ALOT), and there was no change. Dumped all the gas, and put fresh in. Nothing. It WILL prime and start, but won't feed itself after the prime start. If I keep hitting the primer button, it will stay running, as long as you pump it. Everything still looks new on the whole engine.

Why won't it feed itself?
THANKS SO MUCH for your input.
David


sound like you might have a sticky needle but then you got a new carb so I would have to say it could be a compresion problem and it's not drawing fuel in. I have had two of those and have never had that I have had a spring go bad and sticky needle but thats because it had stable in it and that stuff is junk to use in small engines. Ill talk to my budy from Briggs and see if this is a normal problem.

dutch1
05-26-2008, 07:04 PM
You should find a flange on the throttle control that has a hole approximately 1/4" in diameter. One end of the governor spring goes in that hole, the other end in the loop in the governor linkage.

skynyrdfan
05-28-2008, 06:14 AM
Themow,Yes thats the same one I have

skynyrdfan
05-31-2008, 06:29 AM
I fixed it. The tiny spring on the top of carb linkage to the tank frame was gone. $2.00 and all better. Thanks guys

SLR
05-31-2008, 02:04 PM
Informed Updates/fixed goods are most appreciated(hint hint to those that don't)

BSE1911
05-08-2009, 12:51 PM
I fixed it. The tiny spring on the top of carb linkage to the tank frame was gone. $2.00 and all better. Thanks guys

We have exactly the same problem with a B&S. Is there a chance that someone specifies the spring.

thnx

StevieZ
05-08-2009, 09:53 PM
You have 2 options
1. take the numbers off the blower housing, model, type and serial, to a dealer and have them look it up.

2. log on to briggsandstratton.com and input the info under parts manuals.