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SmilinSam

Conquest Briggs 20hp vanguard Carburetor opinions...

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SmilinSam

Touched on this subject sometime back.  To recap, this was/is an ongoing problem that has been getting worse for over a year.. Engine  started running rich . Eventually as time and operation progressed rich enough that it wouldnt run right at all. Change the air filter and it would run great again. You would get a half dozen mows in before the problem cropped up again. Change the air filter and away you go again. Gradually  it was 5 mows between air filter changes , then 4 , then 3..to now its about 2 mows between air filter changes. We rebuilt the carb and that didnt correct the problem.

Heres where I want some opinions.....

At this point I am assuming that the fixed jets are getting worn so bad, that even the slightest amount of dirt in the air filter changes the fuel/air mixture  enough to make it run rich. To me thsi makes logical sense in view of the fact that when you swap a new air filter into it it runs great again  for a couple of mowings

Conditions are not excessively dusty. Using a 54" deck with all the correct plates bolted to it.  I have had the same sort of problem with another conquest using a 50" deck, but nowhere near this bad.

 

I am assuming a brand new briggs carburetor would solve my problems. Just want some opinions before I shell out a couple hundred bucks ....

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SmilinSam

I know, it drives me nuts.

Engine does not use any oil either. Hate to just throw it out but I'm getting tired of this trouble. Cant think of anything other than the carb as being the problem.

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GregB

Quick youtube search found a gasket on the inside behind throttle plates and plastic gasket retainer with 4 holes for air bleed into fuel.  Not all the holes were open the whole way(think gasket misalignment).

 

Have you looked into this also?

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SmilinSam
2 hours ago, GregB said:

Quick youtube search found a gasket on the inside behind throttle plates and plastic gasket retainer with 4 holes for air bleed into fuel.  Not all the holes were open the whole way(think gasket misalignment).

 

Have you looked into this also?

Pretty sure thats not the issue. If so,  the total tear down and rebuild would have fixed it. Besides, it did work fine for several hundred hours before this started. That was well before the rebuild when any misalignment could have happened.

Like I said, as the air filter loads up the air/fuel mix is changing and creating a richer and richer condition. Eventually to the point where the tractor just chugs black carbon rich smoke. Dealt with this all summer last summer and the summer before. Its pretty consistent. The dust conditions here have not been so bad as to warrant changing the air filter every 4 - 6 hours....even using the cheaper box store Briggs branded filters.

There are 2 different filters that can be bought for these engines. One is  cheaper and available at stores like Menards, it has less pleats than the other. The other is more expensive and has more pleats, but is only available through Briggs dealers usually. I dont have the part numbers, but If I find them I'll post them here.

I get more milage out of the better filters on  both engines I have here, but the one I'm griping about now still is super sensative it seems. It used to run good and "normal" up until about 100 hours ago. when it gradually started in on this ever increasing problem path.It has around 1200 hours on it. The other engine has around 900 hours on it and is starting to do the same things but not near as bad.

Edited by SmilinSam

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MARK (LI)

Sam ...call this guy his name is Mike image.png.a33c59e7524486b30443fcd2978c8171.png

He worked for B&S for a long time ...retired now but has a lot of NOS stuff and he is a great guy and can probably help you...good luck with it

image.png

Edited by MARK (LI)

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GregB

Are there air passages behind that gasket the could have gotten gummed up?


I recently used an ultrasonic cleaner from H Freight to clean a Tecumseh carb known for gumming up the narrow passages.  It worked for me.  Used a purple cleaner that was good for all metals.

But a NOS carb should work like that last one until 700 hours , right?

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Tom45

I have an 18 hp Vanguard that would go rich when the governor actuated.  My local Briggs mechanic told me that on it the carburetor has a vacuum passage near the center of the top and that the top of the carburetor was attached by screws around the outside.  This allows a vacuum leak on the inside passage between the main body and lid.  He recommended installing 2 new gaskets under the top which solved my problem.  

Tom

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SmilinSam
1 hour ago, Tom45 said:

I have an 18 hp Vanguard that would go rich when the governor actuated.  My local Briggs mechanic told me that on it the carburetor has a vacuum passage near the center of the top and that the top of the carburetor was attached by screws around the outside.  This allows a vacuum leak on the inside passage between the main body and lid.  He recommended installing 2 new gaskets under the top which solved my problem.  

Tom

On this one the governor actuation actually helps the thing run better. The engine usually performs better under a load the first few mows after a filter change. Eventually that doesnt help anymore though.

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SmilinSam
3 hours ago, GregB said:

Are there air passages behind that gasket the could have gotten gummed up?


I recently used an ultrasonic cleaner from H Freight to clean a Tecumseh carb known for gumming up the narrow passages.  It worked for me.  Used a purple cleaner that was good for all metals.

But a NOS carb should work like that last one until 700 hours , right?

The thing is, with a fresh air filter it runs like a top. At least for the first few mows thereafter.

If it were a plugged passage , wouldnt it run badly all the time?

 

I hope the new carb solves the problems. Cant imagine it not. If it does, its well worth it. If not...next step is to find a nice Kohler to put in thetractor666

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SmilinSam

Adding filter info to this topic.

Two filters out there for the Briggs vanguard twins.

Original filter is 7" od x 5 1/2" id x 2 1/4 Tall Briggs # 394018S..  This is the one found at box stores like  Menards, tractor supply etc as well as at dealers. Black rings with white elements..

Newer style filter is 7 3/4"od x 5 1/2" id x 2  1/4" tall Briggs #692519.  I have only found this at dealers.  Orange rings with yellow element

Talked to a dealer Saturday and he said my symptoms were sounding like the problems that were having when the 23hp vanguards came out.  Briggs solution was to design a new air filter with a wider element and more pleats. This is what I was told anyhow.

I measued the 20hp air filter housing and the wider filter should fit in the 20 as well as others like the 18s. and perhaps 16's. Will be ordering one of these wider filters and get back to this topic to confirm the fit. Pretty sure I have used them in the wifes tractor before though.

 

Edited by SmilinSam
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SmilinSam

The bigger filter mentioned above does indeed fit. However, I did purchase a brand new replacement carburetor off ebay.

Had it on the bench here for weeks and got it installed today. Should have put it in when I first started having problems . Engine runs like new!  Mowed with the Prestige for 2 hours today and not so much as even a cough from it.

dOddOddOd

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SmilinSam
On 4/28/2019 at 6:19 PM, PhanDad said:

Beating a nagging problem is always great.  

Thanks for the update. 

 

...until the next problem arises

Since the april posting above, the tractor has run and performed as it should...till this last weekend.

Mowed for about a half hour or so and all of a sudden engine acted as if running out of gas. Tank was half full according to gauge, and a visual inspection. Found if the choke were engaged it would keep running and not die. Then pull the choke back off  and go. Did this about every 10 minutes for the next hour and a half till the yard was done.

Get about 10 minutes of trouble free mowing, then acts as if out of fuel...work the choke back and forth for about 30 seconds and it would even out and run for another 5 - 10 minutes trouble free. Over and over and over again. Drives one nuts.

Fuel filter is clean and has gas in it and you can see its flowing in and out of the filter.

Got a vacuum fuel pump. My experience with those is that it either works or it doesnt. No intermittent working on those. Or am I wrong on that?

Thought of vapaor lock, but I would think you would need a few minutes of cool down time for things to work again?

Not sure what to look at with this.

About ready to save up some cash and just buy a brand new Kohler command  and put on it......

 

Edited by SmilinSam

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rbstuartjr

Ok this may seem like it is coming from left field but here’s my story. So I have a Cub Cadet Lt1050 that I got a great deal on a few years ago that I use to mow a small vineyard I have. I know it’s a Cub. Anyway it has a Kohler courage vtwin 23hp engine. I fixed all issues with this motor, and there were a few. The biggest issue is the the valve lash has to be checked on because of non hydraulic lifters, like the command engines.

  Anyway a couple weeks ago, it started missing and acting like its running out of fuel so I pull the choke a little and runs fine so I can finish mowing. So I check the fuel and I have 3/4 tank, check fuel pump and filter and I get great flow to carb. So since it was hot when this happen, I’m thinking maybe she might be overheating. So I pull the shroud and she’s pretty clean under there. Still confused.

 I then do some internet research and read that theses engines are very sensitive to the oil changes. The thought being that the dirtier the oil, the harder it is to pull the heat away from the valves, which then causes them to expand and not fully seat and for some reason enriching the fuel by pulling the choke can smooth them out. It was due for an oil change, I really didn’t believe it myself. So I said what the hell.  I then change the oil and air filter, believe it or not the issue went away. I even mowed longer in hotter temps and i dint have any issues. 

 That’s my story with that. 

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SmilinSam

Finally figured this one out......

Tried another fuel pump..in the process found the fuel line is kinked exiting the fuel pump.  A design flaw, which puts the fuel line off the pump too close to the air filter housing , causing it to kink at 90 degrees. The kink reduces the inside diameter by almost half. Also causes the line to crack and detriorate on the inside edge of the kink. Replaced the line, but couldnt do much about the kink.

Unfortunately, these changes did not fix the problem.

Lastly, I pulled the fuel line off the fuel filter and blew compressed air back into the tank. After that it ran for an hour till the yard was done with no further problems.

Guessing the screen in the pick up tube was plugged up. enough to intermittently cause problems. Looks like a post season removal of the tank and a good cleaning out is in order.

Now if I can just figure out the problems with the Ranger and the Grand Marquis....

Edited by SmilinSam

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SmilinSam
1 hour ago, dhoadley said:

Thats a possibility, but there isnt much room under the pump fitting. Another option might be to re-position the fuel pump more up and to the left. I do have an extra pump mount that I could cut and weld on....

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SmilinSam

Well... It quit running completely the last weekend. No fuel to the carb at all. Im thinking that perhaps the fuel line is collapsed inside somewhere, maybe even in the kink from the pump to the carb??

Pulled it into the shop today and ripped all the fuel lines out. Pulled the fitting out of the tank and checked that all out as OK and re-insstalled. Ran new quality rubber fuel lines. Pulled the fuel pump off along with its bracket. Upon closer inspection found that the bracket is drilled for 2 alternate positions. The one it was in when I got it from Edens close out auction in Anamosa, was the lower position which was causing the kink in the line to the carb. Put it in the other position and the lines all run nice and straight.

Runs good now. Maybe its even ...should  I dare say "fixed"?9_9

Edited by SmilinSam
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