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B & S 19 hp Twin sputters and starving for fuel


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07-16-16, 09:14 PM   #1  
B & S 19 hp Twin sputters and starving for fuel

Craftsman Briggs & Stratton 19HP 2 cylinder backfired and since then wont run right or at all. Rebuilt the carb, installed new fuel pump and fuel line. Also replaced coil thinking it wasnt getting a spark.
If it starts it sputters for several minutes then maybe catches on and runs ok at full throttle but if I get off to move lawn furniture or throttle down it wont restart again and run the battery down trying to start. I'm getting ready to junk it.

 
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07-16-16, 11:24 PM   #2  
Could be a loose valve seat. Have you replaced the plugs? A bad plug can do the same thing. Have you checked spark on both sides when it's sputtering? One cylinder is coming and going for some reason I'd say.


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07-17-16, 09:11 AM   #3  
Hmmm.....haven't changed the plugs yet. I'll put a timing light on the plug wires although the coil is bran new including the wires. Can't hurt to replace the plugs.
I hope it's not a loose valve seat. All of this began after throttling down and and shutting down while it backfired through the carb.

 
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07-17-16, 09:35 AM   #4  
When sputtering pull one plug wire at a time and note rpm or dying.

Also, what do the plugs look like?



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07-17-16, 10:00 AM   #5  
The plugs look very good !

 
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07-17-16, 12:38 PM   #6  
Replace them or you can't eliminate them from causing the problem.


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07-18-16, 10:04 AM   #7  
I replaced the plugs with no change in the result.
Still sputters for several minutes until it catches and then runs fairly normal except after shutting down then sputters again at startup.

When the air filter is removed gasoline spouts up and out the top of the carb until it catches and runs normally. This even after I rebuilt the carb and replaced the fuel pump and fuel line.

Again all of this began after it backfired through the carb.
It's as if a check valve is not functioning but all of those components were replaced with new.

I admit that I am unfamiliar with this fuel system design. It uses crankcase pressure to supply pulses for the fuel pump to pump the fuel into the bowl....weird !

Is there something inside the crankcase that acts as a diaphragm that may be damaged ???

Ugh.....!!!

 
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07-18-16, 11:38 AM   #8  
When you rebuilt the carb did you actually rebuild it as in a new kit? Or just cleaning?
Is it a Nikki carb?


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07-18-16, 04:42 PM   #9  
Rebuilt the carb with a kit. All new diaphragms, gaskets, needle and seats etc... The carb was surprisingly very clean inside. Blew out jets and passages with compressed air and used wire to clean very small holes.
Made no difference to the symptom so I then ordered a new fuel pump body, made no difference to symptom.
Did I mention that when it cranks fuel spurts upward out the top of the carb until it catches. I don't know if the spurting is normal or not ( can't imagine that to be normal ). When it final stops sputtering and catches the spurting fuel stops. I'm wondering if there is something I missed in the carb / fuel system..???
Is there a diaphragm inside of the crankcase used to pulse the fuel pump body ???
I'm stumped and that's rare

 
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07-18-16, 05:00 PM   #10  
Give me the numbers off the engine. You didn't answer the carb type...???
If it is a Nikki, the part called the "fuel transfer" houses the main jets. There are o-rings on the jets. There is also an o-ring that seats the fuel solenoid to the fuel transfer.
The kit does not come with the jets or o-rings for them, nor does it come with the fuel transfer and a new fuel transfer does not come with jets or o-rings for them.
Also under the fuel transfer is a conglomerated o-ring that can get pinched or leak or....

If you get it started without sputtering, advance the throttle slowly to full, try a few times this way. If it seems to be ok, then try firewalling/floorboarding it and see if it rears its head. If so then I would say o-rings in the jets or fuel transfer.


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07-18-16, 05:07 PM   #11  
Also the spark plug diagram was not for diagnosing the problem, but how each cylinder is running.
Are both plugs identical? What do you consider
The plugs look very good !
Color? Wet? White? Tan?
I am guessing one cylinder has started running rich and the other lean, which can be determined by examining the spark plugs. If spark, compression, and air are eliminated as being equal to both cylinder, then, that leaves fuel supply...which goes back to the carb.

The spurting gas is likely due to a leaking o-ring in the carb.


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07-18-16, 05:10 PM   #12  
This is a briggs carb. The gas spouting out the top tells all. The float needle is not sealing off all the time. Something may be interfering with the float travel. I've seen the floats hang on something in these carbs but I can't remember what... I don't run across these engines that often anymore. Pop the top off and check it out.


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07-18-16, 05:18 PM   #13  
It might well have a briggs stamp on it, but I bet there is a bigger Nikki stamp on it...I need the engine numbers as there are quite a few variations....

I do agree cheese the sputtering is caused by a rich cylinder...but due to a leaking o-ring and not the float.


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07-18-16, 05:24 PM   #14  
All new diaphragms, gaskets, needle and seats etc...
Diaphragms ?


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07-18-16, 08:39 PM   #15  
The carb has a B & S stamping with these numbers stamped on the carb body:692812
27-531
7810

On the fan housing: Model 42A707/ Type 1251901 / Code 9509265A
Btw....the plugs looked good when I began the troubleshooting but now they were both black and wet.

I pulled each plug wire while running and it ran noticeably worse on either one.

I also attached a timing light to the plug wires and picked up a consistent flash on the R-side but an occasional flash on the L-side although both plugs were firing.

Again this all began after a backfire from the carb during shut down.

( the diaphragm in the kit was for the fuel pump body )

I examined the float during tear down and it was very loose.
The float is hard plastic and floats in a glass without sinking so I assume it's good ???
When I reassembled the float I blew through the fuel inlet and tested the float action to close off air and it sealed. ( not to say it doesn't hang up when fully assembled )
The kit included a new needle and swing shaft for the float too.
Does this carb require an O-ring in the needle and seat ?


Last edited by Mackey; 07-18-16 at 09:08 PM.
 
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07-19-16, 04:57 AM   #16  
Wondering if the float is misformed and needs to be replaced....???

 
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07-19-16, 05:48 AM   #17  
Well that is indeed an old engine and one of the most basic carbs as you can get. I don't recall any float issue that cheese mentioned. About the only thing I recall on those are the throttle shaft seals which is simply a piece of foam type material. That caused a lean condition unlike the rich condition evident by your description of the spark plugs.

According to the IPL http://bsintek.basco.com/BriggsDocum...quFVJ1DajI.pdf, you should have a soft needle and hard seat, so no replacing the seat. You could try polishing the seat with some rubbing compound and a q-tip.....???

Also possible the carb is simply wore out....replacement carb number 693480


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07-19-16, 09:08 AM   #18  
I heated the float in boiling water and gave it an aggressive angle. Made no difference in stopping the fuel from spurting out even though it appears to be sealing when float is seated.

Is it possible the fuel is bypassing the needle and seat ?

A visual check while cranking has the fuel splashing out of a downward vent out to the top but stops once the engine is running normally...ugh ???

 
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07-19-16, 10:22 AM   #19  
Briggs did make thier own carbs. The fuel spurting out the hole in top told me what carb it was (been there, done that a few times, lol).

It's been a while since I worked on one of those carbs, but I believe the hole in top is the bowl vent. Since yours has the plastic float, it's one of the newer of that style carbs (the older ones had brass floats). There was a plastic "flag" sticking off the side of the float on the inside that would sometimes catch on the carb body but it doesn't sound like you have that going on... something is letting it fill too far. Since you can't operate the float while it's in the bowl and see what's happening, it's difficult to tell for sure what it is. Does the float travel freely with no reisitance whatsoever?


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07-19-16, 10:59 AM   #20  
Cheese,
Yes the float does travel freely without any resistance at all.
I'm thinking somehow the fuel is bypassing the needle and seat (float ).
Something is either installed incorrectly or really messed up on the lower carb body.

 
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07-19-16, 03:00 PM   #21  
I pulled the carb again and re-cleaned all of the circuits and ports.
I put the top half with float in a pot of water and watched the float close.
After re-assembly I removed the fuel dump plug and could actually see the float in the drop position and was able to easily push up on the float with a small screwdriver while blowing air through the fuel input and felt it close off.
Also flipped the carb upside down and could hear the float flipping back and forth.
Still sputters and pops.
Also has a new steering gear assembly.
So.....I am out of ideas, probably going to part this POS out on eBay.
It was a junker when I bought it and got a year and a half out of it but now its becoming a money pit and the deck is shot so I'm cutting it loose.
Anybody need parts for a 19hp 42" 6spd B & S Twin ???

Thank you BFHFixit and Cheese !

 
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07-19-16, 04:01 PM   #22  
Shame to hear that, those engines are indeed a dying breed but were one of my favorites. I had and serviced several for years that were always rode hard and put up wet and outlasted any thing they were mounted on.

6spd? Just what is that mounted on BTW?


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07-19-16, 05:05 PM   #23  
Sounds like a craftsman/ayp lawn tractor.

They were/are good engines. Prone to ignition coil problems mostly. When you look down the throat of the carb, there is a hole towards the right front of the carb on top, right? Is that the hole gas is squirting up through? If so, it pretty much has to be either the needle not seating properly or the gasket between the top and the body leaking. I can't think of any other reason barring a big crack in the carb or something like that.


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07-19-16, 06:19 PM   #24  
Prone to ignition coil problems mostly.
Lot of that I think was due to the tight shrouds and not being cleaned out. Was always part of my service.

Do you have one around cheese?
I have only seen one of those engines since moving back to the heartland. They still sound ready for business when tuned and running good!


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07-20-16, 12:32 AM   #25  
Oh yeah, I have two or three, maybe four, plus a few blocks and engine parts in the shop from back when they were more popular. I still keep a coil for them since it's such a common failure on them. Once it's sold, I probably won't reorder one though since I don't need them often anymore.


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07-20-16, 02:04 PM   #26  
The hole where fuel was spitting out of is the downward angled brass tube seen right inside the throat if you are standing facing the engine from the front looking right below your nose! When in the seat and cranking with the air cleaner removed it would spit all the way back to me !

Btw....last night I gave it one more chance and ordered a new float and went back out to try it one more time and burned out the starter.....lol!
It was just too much cranking over the last 3 weeks so now it's really toast.

Yeah, when that twin was running right it had a great sound to it.
Sounded like a 1917 Sopwith Camel I suppose

 
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07-21-16, 12:11 AM   #27  
It was shooting out the brass nozzle, not the vent hole? If so, it's probably not the float/needle problem we thought. I thought it was coming from the hole in the top of the casting. For it to shoot out the nozzle so hard that it sprays you in the driver seat is odd. I have seen them spray out of this nozzle when the engine starves for fuel but not that hard.

When this engine starves for fuel and stalls, it ironically spurts fuel out the nozzle. It doesn't seem right but that's what they do. Did you pull the jet out and clean behind it? It takes an allen wrench (3/16" if I recall correctly) to remove it. That area sometimes gets clogged. If you get it running again, try choking it partially when it starts to die and see if it keeps going. If so, that's the problem.


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07-21-16, 10:11 AM   #28  
Cheese, no, I didn't know how to remove the seat or even that it could be removed.

What's weird is it was behaving like a starving engine but the plugs and the pool of fuel in the bottom of the intake manifold told otherwise. At first I believed it was starving for fuel but learned that it was really flooding and fowling.

So now with the bad carb, a trashed starter and a failing deck, I do not want to put anymore $$$ into it so I'm looking for another fixer-upper.

Thanks for all of the help

 
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07-21-16, 11:13 AM   #29  
Sounds like you know when to throw in the towel, lol

Just for clarification in case someone reads this to diagnose theirs, I'm not talking about removing the seat, but the actual main jet in the bottom of the carb at the bottom of the bowl.

I can't decide if it was leaning or flooding. I know they will spray fuel out the nozzle when they lean out and there will be fuel in the bottom of the intake when they do (when I first ran into this problem, it was quite confusing because this is backwards from what I would expect, seems like it would be flooding not starving) but I never saw one spray fuel out as badly as you're talking about.

Oh well, good luck finding something else to mow with!


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07-25-16, 11:05 AM   #30  
Thanks Cheese.
For now I parked it outside of the garage and maybe will renew my troubleshooting in the Fall. Just too many other projects piling up.
Maybe I'll find a used starter or rebuild kit ???
Btw....I think I pulled that piece out but I'll have to recheck it.

 
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07-25-16, 12:54 PM   #31  
I would suspect a blowby on the diaphragm in the fuel pump. Thinking the fuel is becoming air entrained which messes up the liquid level in the float bowl and pressurizes the bowl. That would account for a lean out and the blowing fuel up through the nozzle about like you're describing. It would be similar to a vapor locking plus a few other things.

I saw where you have replaced the pulse driven fuel pump, but that's where I would go. A simple fix may be an electric fuel pump.

 
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07-26-16, 07:54 AM   #32  
marbobj.....I was thinking along the same lines as far as installing an electric fuel pump.

Do they make electric fuel pumps that can be adapted to these motors ?

 
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07-26-16, 08:22 AM   #33  
Sure. I was having a little problem with my K 341 fuel pump. Replacing it OEM was pretty pricey so I put an electric on it for about twenty bucks. It's just a two wire hook up. The small turbine type doesn't draw a lot of amps but I'd run it through an ignition switched relay.

The fuel lines just go in from tank and out to the carb. It's low pressure so the float valve will control the fuel flow.

Here's a cheapy, but they work fine. You really don't put a lot of hours on one with a lawn mower and there's no rubber in them for ethanol to beat up on.

http://www.ebay.com/itm/New-Electric...RUpMg9&vxp=mtr

 
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07-26-16, 08:33 AM   #34  
That's great, thank you !

I have another problem the upper starter bearing is worn and the shaft wobbles around.
In order to replace the starter I have to remove the magneto but that is frozen on.
I've bent my puller, tried heat and penetrating fluid and I'm out ideas how to loosen this rusted on magneto. Any suggestions....???

 
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07-26-16, 09:56 AM   #35  
You mean the flywheel? Usually all you have to do is put some pressure on it to the outside, then tap it with a hammer. It'll usually pop off. You can put the pressure on it with a puller or use a wedge of wood under it. The thing that takes it off is tapping it with a hammer. Don't wack it so hard you dent it.

That thing sits on a tapered shaft. When you put it back on don't lube the shaft or flywheel with anything - put it together dry.

 
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07-26-16, 10:28 AM   #36  
You don't have to remove the flywheel to take the starter off if you take the engine cover off and the tin cover on the head on the side where the starter is. Then you can get the one starter bolt out easily from above but the other you will have to reach under the flywheel with a 1/2" wrench to take the bolt out. Done it many times.


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07-31-16, 11:59 AM   #37  
marbobj, I've done just what you're describing. I used a puller with penetrating fluid and taping it with a hammer, even applied heat to it.
I'm aware of the tapered shaft.
After I do finally get it off I'll clean the surfaces, not lube before it goes together.

Haven't tried a wedge of wood under it though...

 
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07-31-16, 12:05 PM   #38  
cheese, good to know this.
I'll give it a try... thanks!

 
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