# [SOLVED] 20 hp Briggs &amp; Stratton won't run



## etvolare (Jul 13, 2012)

My B&S 20hp mower worked fine the last time I used it. Last week, I started it up and it would run for < minute and then die. I could re-start it, but it would die again. Figured fuel problem, so I started at the tank, replaced the fuel line to the carb and a new fuel filter. The carb has an integral diaphram fuel pump and I put a kit in it. Changed the carb body gasket and the needle & seat. I started it up aqnd it ran fine for about 15 minutes then died. I could restart it, but it would only run with full choke. I checked the float bowl and had about 1/4" of fuel in it. I suspect its a fuel pump issue, and as a last resort, I was going to put an inline 1-2psi 12v pump to replace the diaphram pump. Anything else I should check??
Model # 46077
Type 1276-01
Year 1997
Thx
etvolare


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## boutselis (Jul 4, 2012)

*Re: 20 hp Briggs & Stratton won't run*

The first thing I would want to know is how old is your gas and how long was it between the last time you used it and this time? 

Did you soak the carb in cleaner. If there is some varnish in the carb then thats probably what is causing the problem I have had great success with soaking carbs in sea foam. it doesn't harm any of the gaskets or O rings but cleans the carb up very well. I usually only remove the bowl and anything else thats easy to get at. I never tough the plugs. 

An over night soak is the first thing I would do.


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## CCT (Mar 21, 2009)

*Re: 20 hp Briggs & Stratton won't run*

Remove the tank, drain and flush. (or flush and drain)


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## Basementgeek (Feb 7, 2005)

*Re: 20 hp Briggs & Stratton won't run*

Hi and welcome to TSF

Make sure the vent on the gas tank is clear. 

BG


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## etvolare (Jul 13, 2012)

*Re: 20 hp Briggs & Stratton won't run*

I didn't soak the carb, but dismantled it and shot carb cleaner thru every opening and then ran a fine wire thru them. 

I thinking now it might be a vacuum leak in the line that operates the fuel pump. Does anyone know what the vacuum reading should be?


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## etvolare (Jul 13, 2012)

*Re: 20 hp Briggs & Stratton won't run*



Basementgeek said:


> Hi and welcome to TSF
> 
> Make sure the vent on the gas tank is clear.
> 
> BG


Thanks for the welcome.

I wondered if the >100° temp was causing a vapor lock, so I tried running it with the gas cap loose, but that had no effect. I will check and see if the tank has any other vents other than the small hole in the cap.


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## etvolare (Jul 13, 2012)

*Re: 20 hp Briggs & Stratton won't run*



CCT said:


> Remove the tank, drain and flush. (or flush and drain)


Last fall I ran the tank completely dry. This spring, I added a bottle of heet when I gased it up again, just in case condensation had formed. It fired right up and ran fine.

It was about 2 weeks after the initial use that the problems developed. I didn't have to add any gas between those times. The only difference I can see is I gained a little weight!!! LOL


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## CCT (Mar 21, 2009)

*Re: 20 hp Briggs & Stratton won't run*

I was thinking more of debris floating inside that gets sucked down to the outlet and blocks it.


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## etvolare (Jul 13, 2012)

*Re: 20 hp Briggs & Stratton won't run*



CCT said:


> I was thinking more of debris floating inside that gets sucked down to the outlet and blocks it.


Good point. Time to drain and clean the tank.


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## boutselis (Jul 4, 2012)

*Re: 20 hp Briggs & Stratton won't run*



etvolare said:


> Good point. Time to drain and clean the tank.


From everything you said so far i would say thats the best bet; maybe,

My first post was about a john deere mower. I got it running after cleaning the carb and the tank. I shut it off and it wouldn't start again. I took the bowl off and even though I cleaned the tank and fuel line and carb once already there were specks of debris in the bowl. I took the tank off a second time and sure enough there was dirt I missed the first time. I recleaned the carb and then it ran fine. 

The difference is that my mower did not have a fuel filter. I think you said yours does and its new. That should have stopped any trash.


IF you said it runs with the choke on, I mean fully runs and not just starting, then the problem may be a leak. I know with chain saws and string trimmers the tiniest air leak will do that. IT will run on choke but not with out.


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## etvolare (Jul 13, 2012)

*Re: 20 hp Briggs & Stratton won't run*



boutselis said:


> From everything you said so far i would say thats the best bet; maybe,
> 
> My first post was about a john deere mower. I got it running after cleaning the carb and the tank. I shut it off and it wouldn't start again. I took the bowl off and even though I cleaned the tank and fuel line and carb once already there were specks of debris in the bowl. I took the tank off a second time and sure enough there was dirt I missed the first time. I recleaned the carb and then it ran fine.
> 
> ...


I thought I would recirculate the gas with a fuel pump. I hooked the pump downstream of the filter and I figgered if there was any crap in the tank bottom, I would see it in the filter. As soon as the pump started, I saw air bubbles in the filter and the pump output was about 1/3 of what it should have been. I went ahead and dismantled the rear half and found that the fuel line I put on was some metric size and didn't fit real well on the barb. When I clamped it down with a screw type clamp, it must have created a small gap between the barb and the hose. I'm on my way to NAPA, with the barb, to get new fuel line. I hope this does it, I'm almost out of hair!!!

BTW: I had 4 lbs of vacuum at the fuel pump intake while cranking. Don't know what the correct spec is, tho.


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## etvolare (Jul 13, 2012)

*Re: 20 hp Briggs & Stratton won't run - NOW IT DOES!!!*

:dance:All FIXED!!!

Figured it happened this way....
Diaphram got a hole in it. Didn't know it.
Saw some cracks in the fuel line... Changed it out. Unfortunately, it wasn't ¼" id and allowed air to get sucked in.
Next changed out the fuel pump diaphram and still not running right.
Float bowl had very little gas in it so I figured the needle was sticking. Changed that.
Would run for a while with the choke fully pulled out... 
Indicates bad air/fuel ratio.
Changed to correct size fuel line.... WaLaaa
Cut the grass!!!
Even the extra weight didn't slow it down.

Thank you all for taking the time to help me.
See you again
etvolare


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## Basementgeek (Feb 7, 2005)

*Re: 20 hp Briggs & Stratton won't run*

Good to hear 

BG


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## boutselis (Jul 4, 2012)

I thought air might be the problem. 

good work.


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## etvolare (Jul 13, 2012)

boutselis said:


> I thought air might be the problem.
> 
> good work.


Thx for your input


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