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View Full Version : Briggs and Stratton won't run correctly


briggsman65
09-05-2005, 01:25 AM
I just acquired a Walmart special mower from a friend of mine. It has 3.5HP B&G motor on it. When I got it it would start but only run for a few seconds about 30 seconds and shut off. If I pushed the primer bulb it would keep running. So I pulled the gas tank and carburetor off. It is a very simple set up. I unscrewed the carburetor off of the gas tank and sprayed it with carburetor cleaner. When I put it all back together same thing. So I took it back apart again this time removing the gaskets and really spraying. Didn't really see any dirt but sprayed anyway. This time when I put it back together it now runs without shutting off. Only one catch it doesn't run correctly. There are no carburetor adjustments like screws or anything. When it runs it runs low and high consistently.........not at one single high rpm like it is supposed to so that you could actually cut grass with it. Is there something else I should check now? I put a new plug in it, new gas, cleaned the flywheel which really wasn't rusty or dirty. The mower is only 3 years old and for the most part in like new condition. Is it still carburetor problems? Air filter is cleaned too. Thanks ahead of time for your help.

fixer67
09-05-2005, 01:40 AM
Post the model , type , code numbers for more help

briggsman65
09-05-2005, 01:57 AM
model 90902
type 2005 B2
code 00102552

Restrorob
09-05-2005, 09:45 AM
model 90902
type 2005 B2
code 00102552

Something is wrong with these numbers ! There is only one 90902 listed and it has spec. # 3309 and has a old pulsa jet carb. on it, No primer bulb.
If you do have the plastic carb. which should be on this newer unit make sure the main jet is open and replace the diaphragm.

briggsman65
09-05-2005, 10:24 AM
model 90902
type 2005 B2
code 00102552


model # in fact is wrong it should be 9D902

I guess I should get some glasses...lol

Restrorob
09-05-2005, 01:41 PM
model 90902
type 2005 B2
code 00102552


model # in fact is wrong it should be 9D902

I guess I should get some glasses...lol

Ok, Remove reference # 363 screen and make sure it's clean, Then check the main jet under the screen. Then replace ref. # 394 diaphragm. Make sure the air filter is in place when test running, This carb. is a fixed jet style and will not run properly with the air filter off.
Also check ref. # 612 pick-up tube and make sure that screen is also clean.
Good luck

briggsman65
09-05-2005, 08:11 PM
Did all of that................My neighbor came over and said "hey" I have one of those exact mowers I am using for parts you can have anything you need off of it. After 6 times removing my carburetor I figured what the hey I will try his carburetor. Well if I had to go off of looks of it I would have said no way is it going to work either. When I took his carburetor off it had obvious dirt and deposits on all the screens and things (when I had mine off I saw NO dirt). I cleaned it up and put it on and violla I now have a running mower. Still real curious why the one that was on the mower didn't work. By looks and cleanliness alone it should work. But oh well.........thanks for the help everyone.

briggsman65
09-05-2005, 08:11 PM
Did all of that................My neighbor came over and said "hey" I have one of those exact mowers I am using for parts you can have anything you need off of it. After 6 times removing my carburetor I figured what the hey I will try his carburetor. Well if I had to go off of looks of it I would have said no way is it going to work either. When I took his carburetor off it had obvious dirt and deposits on all the screens and things (when I had mine off I saw NO dirt). I cleaned it up and put it on and violla I now have a running mower. Still real curious why the one that was on the mower didn't work. By looks and cleanliness alone it should work. But oh well.........thanks for the help everyone.

briggsman65
09-05-2005, 08:11 PM
Did all of that................My neighbor came over and said "hey" I have one of those exact mowers I am using for parts you can have anything you need off of it. After 6 times removing my carburetor I figured what the hey I will try his carburetor. Well if I had to go off of looks of it I would have said no way is it going to work either. When I took his carburetor off it had obvious dirt and deposits on all the screens and things (when I had mine off I saw NO dirt). I cleaned it up and put it on and violla I now have a running mower. Still real curious why the one that was on the mower didn't work. By looks and cleanliness alone it should work. But oh well.........thanks for the help everyone.

briggsman65
09-05-2005, 08:17 PM
Wow I am having all kinds of good luck.................my message posted 3 times.

jhip1264
09-05-2005, 09:28 PM
I have several mowers like the one you are talking about.The seal between the carb and the primmer plate is bad, that's why as long as you keep primming the bulb it will stay running.Replace the bulb first, that will usally fix the problem. If not, replace the whole primmer assembly, it is a common problem on these. I have had to replace every one of mine, some twice!

Restrorob
09-05-2005, 10:33 PM
I have several mowers like the one you are talking about.The seal between the carb and the primmer plate is bad, that's why as long as you keep primming the bulb it will stay running.Replace the bulb first, that will usally fix the problem. If not, replace the whole primmer assembly, it is a common problem on these. I have had to replace every one of mine, some twice!

How about going back to the pic. I posted and get a reference number on the seal and or plate you are talking about, You kinda lost me on this.

fixer67
09-06-2005, 11:45 PM
How about going back to the pic. I posted and get a reference number on the seal and or plate you are talking about, You kinda lost me on this.

I thank this is what he is talking about which has nothing to do with this model in question here. This is from a 122H02-0117

Restrorob
09-07-2005, 07:12 AM
I thank this is what he is talking about which has nothing to do with this model in question here. This is from a 122H02-0117


I knew what he was refering to, Just wanted him to see it didn't apply to this application. lol

Restrorob
09-07-2005, 08:09 AM
I have several mowers like the one you are talking about.The seal between the carb and the primmer plate is bad, that's why as long as you keep primming the bulb it will stay running.Replace the bulb first, that will usally fix the problem. If not, replace the whole primmer assembly, it is a common problem on these. I have had to replace every one of mine, some twice!

Just for reference to ALL, This plastic plate will warp in time and cause a air leak in the primer system thus causing no fuel to enter the carburetor throat while pushing the primer bulb. If a engine starts and you must continue to push the primer bulb to keep it running THAT tells you the plate and gasket are fine and the primer system is working properly. You then have a internal carburetor problem, (trash, water ect.) Obstructing the main jet in most cases, That means a good carb. cleaning should fix the problem.

briggsman65
09-07-2005, 12:26 PM
Just for reference to ALL, This plastic plate will warp in time and cause a air leak in the primer system thus causing no fuel to enter the carburetor throat while pushing the primer bulb. If a engine starts and you must continue to push the primer bulb to keep it running THAT tells you the plate and gasket are fine and the primer system is working properly. You then have a internal carburetor problem, (trash, water ect.) Obstructing the main jet in most cases, That means a good carb. cleaning should fix the problem.


Well I cleaned and cleaned and cleaned the carburetor..............It would not stay running. So as I said in the earlier post it has an old dirty one on it now that I cleaned up and runs like a champ!

Restrorob
09-07-2005, 01:17 PM
Obstructing the main jet in most cases..


I understand what you did and thats why I used this term loosely, I have ran across quite of few carbs. that just wouldn't clean up so glad you got it running with another carb. and minimal expence.

stratton-
06-16-2008, 09:34 PM
I just replaced the gasket and diaphragm from the dealer it was $4.00. There are 2 different kits for my engine depending on the mfg date code…they look identical...the counter parts guy said he only showed one. I checked back on the bns site ipl and sure enough he gave me the wrong one...anyways my grass was long so I tried it. I swear the mower now runs stronger than the day I got it in 2000. The motor always sounded kind of gaspy but I always thought it was just the way newer engines must sound. The symptom that led up to mine was that the primer bulb would not work that well and then one day the up and down hunting revving action started. The bulb now squirts with good pressure every time.

-------------------------------------------------------------------------------------

My tips if your thinking of doing it yourself...remove the gas tank first(carb is attached to the top of tank) it is just 2 bolts one on front and one on the side...you don't even have to take the cover off the engine this way. Next take the carb off the tank, I looked at the jet screen and the other cup shaped screen and they didn’t look bad. Of course I wiped stuff down where I could to get the obvious black gunk away from surfaces that come into contact with fuel. The diaphragm goes on the shiny metal machined surface on top of the tank and the gasket gets sandwiched between the top of the diaphragm and the bottom of the carb. Be over cautious when handling the springs I busted the hook loop on the small one but just bent it back in place and its holding so far. Now I practically have to run behind this thing to keep up when its in self propel mode..pretty easy fix and bns web site makes it easy to identify parts but bns site does not really give you a good how to....that's what lawnsite.com is for!...when I fix something like this it makes me feel good about the high cost of my high speed internet connection!

Partsangel
06-16-2008, 10:41 PM
This mowers only three years old

model 9D902
type 2005 B2
code 00102552


This thread is moving fast...the first thing I noticed was the mower was made in 2000/10/25 on production line 52.

Going from fast speed to low speed is what they call Hunting/starving for gas in our industry, try OMG how do you explain this...Ummmm taking the tention/pull/ off the govenor spring, this will lower your RPMs to 3600 and your engine should level out to normal.
You might want to borrow somebodys small engine Tach to check the RPMs.

I hope this helps


Mke

INOV8TN
04-10-2009, 04:21 PM
Working on g/f mower: B&S 9D902 2005 B2 020426551 - Doesn't run. Won't even sputter.
.
How do you clean the tank? I poured out and saved the old gas and some ugly reddish sediment. I put some clean rocks in and new gas and shook it for 10 min and poured out and saved more dirty gas and sediment. Second time it was much better although not perfect. The diaphram seems stretched but intact. Spring is OK. Screens aren't perfect but appear to be usable. Blew out the fuel pickup. The primer bulb seems to work now.
Spark plug is original, cleaned, gapped at 0.030" and although wet is no longer getting fouled. Have spark but removed magneto. What's the spacing I should use between the magneto poles and the flywheel?
Thanks in Advance.

betmr
04-10-2009, 05:58 PM
Loosen the coil, put a buisiness card between it and the fly wheel, rotate the flywheel till the magnet pulls the coil in, with the card between. Tighten down the coil bolts, take the card out....your done.

P.S. It's called The Air Gap

INOV8TN
04-10-2009, 09:10 PM
I used a 'home brew' card (from Avery 8879 stock). I guess as long as the AirGap is greater than the bearing runout I'm in good shape - Yes? :)

B&S says the plug should be gapped at 0.030" so I guess my 0.035" is close enough for jazz.

How about cleaning the gas tank - carburetor cleaner?

Any other thoughts?

Thanks!

betmr
04-11-2009, 12:37 AM
I used a 'home brew' card (from Avery 8879 stock). I guess as long as the AirGap is greater than the bearing runout I'm in good shape - Yes? :)

B&S says the plug should be gapped at 0.030" so I guess my 0.035" is close enough for jazz.

How about cleaning the gas tank - carburetor cleaner?

Any other thoughts?

Thanks!

The thickness of a business card is right for the air gap. 0.030" IS the spark plug gap, close does not count here, 0.035 is 5 thousandths of an inch more space that the current must jump. Re-gap your plugs to 0.030"

You did good cleaning the gas tank, Don't re-use that gas, dispose of it with oil recycling. gas starts to break down in 30 days or so, try to use fresh gas.

Carburetor cleaner, I get Carburetor, Choke & Throttle body cleaner, in a spray can with the straw (Like comes with WD40) You can't just spray in in the intake vortex, you use it inside to spray through all the jets and screens.

My other thought is that you be sure to Prep your Equipment for storage at the end of the season. What I do for storage is the following:

1) Run machine till it is at operating temperature, then change the oil.
2) Mix 1 Gallon of gas with fuel stabilizer, as per directions.
3) Empty gas tank, and run machine till it is out of gas.
4) Put just enough of the stabilizer/gas mix in the tank to start and run for a few minutes.
5) Run it again till it is out of gas. Now, any gas that is still in there is treated with fuel stabilizer. Gasoline starts to turn to Varnish as it ages, this is why so many people have trouble at start up time next season, they leave the gas in there and the varnish starts to clog the jets (which are meant to be an exact size opening, to properly atomize the fuel) in the Carburetor.
6) Take out the spark plug, & put a tablespoon of 30 oil in the hole, and turn it over a few times to coat the cylinder walls. Then put the plug back in.
7) And this is important, Take the gas you drained from the tank, any gas you have in cans in the shed, the garage, and the work shop, Any and all the gas you won't use within 30 days, and Dump it.....in your car, or truck and use it up. Gas goes bad over time.
8) You should now be ready to go next season, put in new fresh gas, start 'er up and go...(If she smokes a little at first, not to worry, remember the oil you put in the cylinder for protection is burning off)

I hope this information was help full to you. Just let me say one thing, when you post about your equipment, try to include a Model year, or at least some reference to age. Age can be very help full in diagnosis. Like people, old ones can be expected to have different problems than young ones.

INOV8TN
04-11-2009, 02:05 AM
Thanks again.

Wow! Great response. :)

I will regap the plug to 0.030" as you stated.

Post #20 on the previous page of this thread is my first and provides the context (model/style/production date :: 9D902 2005 B2 020426 - if I'm reading the code right) as well as the precipitating issue (won't start) you found lacking.

Thanks also for the details of the winter put-up. That alone is worthy of a 'sticky'.

All the best.

- Bill

betmr
04-11-2009, 02:30 AM
Glad I could help my friend !:usflag: