# A question for carburetor guru's



## NRP (Dec 28, 2015)

Hello all. I am in the process of getting a '79 Toro 8/26 back in running order, and I am having an issue with the updraft carburetor. The engine is a B&S 8hp, and this is a style of carb that I have never worked on before. It was rebuilt with a B&S kit I picked up on ebay, and I cleaned both sections of the carb body in a sonic cleaner before reassembly. The problem I am having is that when I turn on the gas at the tank, everything seems fine, no leaks. When I begin cranking the engine and vacuum is applied to the carb, it starts to leak gas out of the intake, and the upper section of the carb body is damp with fuel. When I stop cranking the engine, the fuel leak stops. I have had it apart and back together 3 times now checking and rechecking my work, all with the same result. Was I supposed to put thread sealer on the main jet before screwing it into the lower body? Is there a common area on the upper or lower sections of the body that they crack? I thought I eliminated the needle and seat as a problem when the leaks stopped after I stopped cranking the engine. Thank you in advance for your time, and any advice would be appreciated.


----------



## dbert (Aug 25, 2013)

Sorry I cannot help as I've not owned one, but to clarify your question for those that can, is it like this one?
Disassembly, Cleaning and Repair of Briggs and Stratton Medium Two-Piece Flo-jet Carburetor


----------



## NRP (Dec 28, 2015)

Yes, it is exactly like that one.


----------



## Grunt (Nov 11, 2013)

I also haven't worked on this type of Briggs carb and I'm sure classiccat will be along to bail us out. 

I would take a wild guess and say your carb is good and "maybe you have a stuck or not completely closing intake valve in the engine. Have you checked your valve clearances or done a compression test? Does the engine start and run well? If it does, my theory is wrong.


----------



## NRP (Dec 28, 2015)

Hello Grunt,
Yes the engine now starts and runs. When I had it apart, I checked the valve lash and everything was within spec. I got it running today and after making a mess with spitting gas, it cleared up after the engine was running. I can't believe this is normal.


----------



## classiccat (Mar 1, 2014)

I have a little bit of experience with the old updraft carbs.

The leak is either from incorrect float height/stuck-float/leaky-inlet or the emulsion tube not seating properly. 

Here's a good illustration I found from the old "inter-web"









be careful with the emulsion tube... it is very soft and you need a screwdriver that seats very snug/squarely on the head. 

Briggs and Stratton does still cell the special screwdriver (pns 19061 and 19062). I ground down my own in a pinch (and purchased the B&S for my next updraft!).


----------



## UNDERTAKER (Dec 30, 2013)

classiccat said:


> I have a little bit of experience with the old updraft carbs.
> 
> The leak is either from incorrect float height/stuck-float/leaky-inlet or the emulsion tube not seating properly.
> 
> ...


*Once again your DA-MAN there BROTHER CC.:icon-bow:*


----------



## AandPDan (Nov 18, 2014)

Another common problem is that the upper carb body is warped and won't seal.


----------



## Jackmels (Feb 18, 2013)

Why Mess Around? NEWEST Carburetor for BRIGGS &STRATTON 390323 394228 7HP 8HP 9 HP Engine Carb | eBay


----------



## NRP (Dec 28, 2015)

Classiccat: Once again thanks for your help. I have had the emulsion tube in and out several times now. I'm going to try to concentrate on that. Back to square one once again today. 

AandPDan: That is something I have not checked yet, and is on the list for today. Thanks again!


----------



## cranman (Jan 23, 2016)

I'm with Jack....go E-bay. I had a problem with my 8-26 and that solved it.


----------



## classiccat (Mar 1, 2014)

Jackmels said:


> Why Mess Around? NEWEST Carburetor for BRIGGS &STRATTON 390323 394228 7HP 8HP 9 HP Engine Carb | eBay



Carb bodies are the same however I'm pretty sure the emulsion tube orifices are different (_I tried using an 8hp tube in a 7hp engine_). Do they send an assortment of tubes? :smiley-confused013:


----------



## 43128 (Feb 14, 2014)

i used a 7hp carburetor from a toro 726 on an 8hp giant vac leaf blower. worked fine


----------



## classiccat (Mar 1, 2014)

43128 said:


> i used a 7hp carburetor from a toro 726 on an 8hp giant vac leaf blower. worked fine


I couldn't get an 8hp carb to work on a 7hp engine (very rich) until I swapped-out the emulsion tube from a 7hp rebuild kit.

do you want my 8hp emulsion tube for your leaf vac?


----------



## 43128 (Feb 14, 2014)

Nah never had an issue in my case I just tweaked out the main and idle jet a little bit. No issues


----------



## NRP (Dec 28, 2015)

Jack and Cranman, I may be taking your advice. Spent this afternoon trying to get the original carb to work with no luck. The carb I have is a briggs P/N 391889, and they want $140 for the B&S one.:eeek: As much as I would like to keep it all made in Wisconsin Briggs, that's not going to happen. Has anyone had anything other than good luck with the cheaper replacement carburetors?


----------



## RIT333 (Feb 6, 2014)

NRP said:


> Has anyone had anything other than good luck with the cheaper replacement carburetors?


The one recommendation that I have heard is to make sure that you get one with adjustable mixture screws. Otherwise, all is good.


----------



## Blosumsno (Dec 7, 2016)

I've had engines with these carbs but never an issue that tweaking the needles couldn't fix.

It's amazing how inexpensive these repro parts are: I just ordered a spare Carb for my Snapper's Tecumseh for less than $14 also from eBay.


----------



## NRP (Dec 28, 2015)

Update: I stopped wasting time today and ordered a new replacement carburetor. I figured I have wasted enough time :icon-deadhorse: and decided to cut my losses and move on. I should have known better than try to resurrect a 38 year old carb on a machine I pulled out of someones back yard not knowing the last time it ran. Thanks again to everyone that responded, and I will update later after the parts get here.


----------



## 43128 (Feb 14, 2014)

sometimes you get lucky and they run great after a quick clean and a little tweaking. for example, i bought my landa wheelbarrow pressure washer for only 50 bucks. brought it home the gx390 had a half tank of NASTY gas. i gave it a hit of carb cleaner and it fired up first pull and ran without choke. it surged for the first ten minutes but it cleared itself out. that power washer now starts first pull every time i go to use it and runs flawlessly. other times no matter what you do you have to replace the carburetor


----------



## amuller (Jan 3, 2016)

I just did one of these carbs for the first time on a lot of years, and it leaks while sitting. Thanks for the helpful description of potential leakage paths.

Most of the literature on these carbs says the float is supposed to sit level with the body when inverted. But the Briggs video on these, while *saying* that, *shows* the float sitting higher than parallel (when inverted). That's the way I found mine. I bent the float tank to level it, but am wondering if I did the right thing, or if the liquid level is now too high.

Briggs also describes a procedure for lapping the emulsion tube seat into the lower body (by grinding off the threads so it can be rotated using valve grinding compound. Obviously this requires sacrificing a tube. Have people found this necessary?

Any experience with the Ebay/Chinese carbs? $16.85 with free shipping is tempting to try.

Thanks!


----------



## NRP (Dec 28, 2015)

amuller said:


> I just did one of these carbs for the first time on a lot of years, and it leaks while sitting. Thanks for the helpful description of potential leakage paths.
> 
> Most of the literature on these carbs says the float is supposed to sit level with the body when inverted. But the Briggs video on these, while *saying* that, *shows* the float sitting higher than parallel (when inverted). That's the way I found mine. I bent the float tank to level it, but am wondering if I did the right thing, or if the liquid level is now too high.
> 
> ...


amuller- you chimed in just in time. I think you did the right thing by leveling your float. Out of all the times I have had these carburetors apart, I have set the float to level and that was plenty good to seat the needle. I have not heard of the procedure you mentioned for lapping the emulsion tube, although I would be curious to learn more. As for the ebay carburetors.. I just installed one on my 8hp briggs. Before installation I verified fuel flow from the tank, spark, and needle and seat operation by blowing through the carb before installing it. The new carb came with all adjustment screws turned all the way in, no instructions as to initial settings, and no further information. I have spent an entire day trying to get it to work, and the best I can do is to get it to run for a few seconds on the gas it loaded into the lower body before it shuts off like it ran out of gas. The kicker is it then leaks gas out of it after sitting for a while! :icon-shrug: Cheap price and free shipping were attractive to me as well. However I seem to be in the process of learning yet another lesson on how I got what I paid for.:banghead:


----------



## RIT333 (Feb 6, 2014)

Wow - so the mixture screws were not factory set - that sucks. Seems like usually 1 1/2 turns will usually get you running, and then you can fine tune form there, but who know what is "normal" in China ???


----------



## jimchevy (Jul 10, 2016)

I never saw that carb before but I know if the seat gasket for the needle is installed upside down (taper up) it will leak on most carbs.


----------

