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TB30 R Back fires every few minutes.

#1

W

whanner

I have a 2 year old TB30 R Riding mower that has run fine for 2 years but this year has started back firing every minute or so. I have put a new plug in it and added Sea Foam to the gas but it didn't help much....any suggestions on what could be causing the problem? I noticed a spark from a factory hole in the carburetor behind the bolt that hold the carb in place...that seems odd to me. Here's the bolt where I notice the spark...notice the carbon Carb.jpg


#2

Boobala

Boobala

Looking at your pic it appears the carb to intake manifold GASKET is leaking, try installing a new gasket, and be sure you snug it up real good, it may solve that issue....... DO NOT overtighten it's a plastic manifold.

I THINK the p/n for the gasket is 692137, (that's the NON-restrictor gasket) yuo haven't supplied your engine info so I'm shootin in the dark. When asking for help on the forums, ALWAYS, include your machine's info. ( see example ) .....

GET INFO.JPG


#3

EngineMan

EngineMan

Check the HT lead and see the the coil is clean around it, maybe the spark going to ground...! you could remove the bolt and see what the hole is for.


#4

Boobala

Boobala

After re-reading your post and checking the pic AGAIN, you mentioned a HOLE in the carb, there should be a welch-plug in there, or are you just seeing the indentation where the plug is installed, you would get a better look by removing that bolt,see enclosed pic .........

welch_plug.JPG


#5

W

whanner

Thanks for all the input guys... I'm not familiar with a welch-plug, to me it looks like the intake should'nt have that opening like maybe the plug is missing? going to look at it this week end.
thanks again!

Boobala said:
After re-reading your post and checking the pic AGAIN, you mentioned a HOLE in the carb, there should be a welch-plug in there, or are you just seeing the indentation where the plug is installed, you would get a better look by removing that bolt,see enclosed pic .........

View attachment 36515
Click to expand...


#6

W

whanner

The motor is a Briggs and Straton 21r7 0039. Something else... the governor keeps trying to regulate the rpm. I i hold it in place it does ok.


#7

dfbroxy

dfbroxy

Try checking the valve gap. The intake valve may be staying open just enough to backfire into the carb. This could also be causing the problem with the gov. also


#8

Boobala

Boobala

whanner said:
The motor is a Briggs and Straton 21r7 0039. Something else... the governor keeps trying to regulate the rpm. I i hold it in place it does ok.
Click to expand...

THAT model # DOES NOT JIVE with anything I've checked, you must be reading the wrong numbers, I suspect you have a single cylinder OHV engine with THAT model of carb, look through the enclosed manual, ( in link) and see if it's familiar......

https://docs.google.com/file/d/0B6NaqjIxWV1ybEN0LWo3azl6OUU/edit

The engine info will either be on the engine "shroud" or the valve cover


#9

ILENGINE

ILENGINE

Boobala said:
THAT model # DOES NOT JIVE with anything I've checked, you must be reading the wrong numbers, I suspect you have a single cylinder OHV engine with THAT model of carb, look through the enclosed manual, ( in link) and see if it's familiar......

https://docs.google.com/file/d/0B6NaqjIxWV1ybEN0LWo3azl6OUU/edit

The engine info will either be on the engine "shroud" or the valve cover
Click to expand...

Boo 21R707-0039. He is missing the welch plug that covers the transfer port hole for the idle circuit of the carb. Which could be causing the governor surge since it would be trying to run on the high speed jet only. the welch plug isn't available as an individual part from briggs but is a standard welch plug available from Walbro or other aftermarket suppliers such as Stens or Oregon.

the backfire could be due to a valve issue, but could also be a side effect of running lean due to the missing plug.


#10

Boobala

Boobala

ILENGINE said:
Boo 21R707-0039. He is missing the welch plug that covers the transfer port hole for the idle circuit of the carb. Which could be causing the governor surge since it would be trying to run on the high speed jet only. the welch plug isn't available as an individual part from briggs but is a standard welch plug available from Walbro or other aftermarket suppliers such as Stens or Oregon.

the backfire could be due to a valve issue, but could also be a side effect of running lean due to the missing plug.
Click to expand...

I too thought about a valve adjustment, but looking at his pic, and him NOT mentioning a hard-start condition, I ventured to the carb first, yes it certainly can be from valves causing the back-fire and I think he should adjust them regardless. I am in total agreement with you.


#11

W

whanner

thanks for all of the suggestions... haven't had time to look at it yet, Going to start with a Welch plug and go from there. you guys are great!


#12

Boudreaux In Eunice La.

Boudreaux In Eunice La.

I agree with IL Engine, the plug not being there can cause the gov to be going to the THOR mode........LOL


Might as well get a kit since they come with a welch plug and redo the carb...... The plug is put in place and then with a punch and hammer punch it in......

BOO can you put that Nikki carb link on here like you did today for that other Nikki Carb we are helping on the Briggs section ??

That's a very detailed link for Whanner to go by ~!~!


#13

Boobala

Boobala

Boudreaux In Eunice La. said:
I agree with IL Engine, the plug not being there can cause the gov to be going to the THOR mode........LOL


Might as well get a kit since they come with a welch plug and redo the carb...... The plug is put in place and then with a punch and hammer punch it in......

BOO can you put that Nikki carb link on here like you did today for that other Nikki Carb we are helping on the Briggs section ??

That's a very detailed link for Whanner to go by ~!~!
Click to expand...

ASK and yee shall receive !! ..

http://outdoorpowerinfo.com/repairs/briggs_intek_single_ohv_nikki_carb.asp


#14

Boudreaux In Eunice La.

Boudreaux In Eunice La.

Merci Bien Boo ~!~!~! You a great guy ~!~!


#15

Boobala

Boobala

Boudreaux In Eunice La. said:
Merci Bien Boo ~!~!~! You a great guy ~!~!
Click to expand...

Well you are too Bo !! .. :thumbsup:


#16

K

kh0432

Mine was doing the same thing. I was lucky because when I took the carburetor off to clean it I noticed the welch plug was turned sideways and ready to fall out, If the plug hadn't been there I probably wouldn't have noticed it missing. Put it back in with a flat punch then covered it with epoxy.


#17

Boudreaux In Eunice La.

Boudreaux In Eunice La.

kh0432 said:
Mine was doing the same thing. I was lucky because when I took the carburetor off to clean it I noticed the welch plug was turned sideways and ready to fall out, If the plug hadn't been there I probably wouldn't have noticed it missing. Put it back in with a flat punch then covered it with epoxy.
Click to expand...
I will speak for everyone that replied to your post ,Most of us are not on here anymore , but I check in every now and then ..... GLAD the info helped out ..... I go live every now and then on my you tube channel with friends and we do the same thing on there as I did on this forum .... I go by Cajun Coin Hunter ...


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