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Sears tractor engine dies when blades disengaged


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09-23-17, 03:12 PM   #1  
Sears tractor engine dies when blades disengaged

Hi,
My questions are regarding a Sears Craftsman LT1000 Model #917.275371 17.5 HP IC OHV with Briggs Engine Model#31C707 Type No. 0230-E1.
I'm having two issues that I do not know if are related ore not.
1) I can mow my entire lawn (about an hour) and then when I disengage the blades, the engines sounds really rough and sometimes stalls out completely. When I google searched this issue, it seems everyone else had the opposite problem (that the tractor ran fine until the blades were engaged and then the engine stalled.)
2) Twice recently when the tractor sat idle for over a week, the battery was completely dead. The battery would charged up fine and if used again within a few days would start fine. Can this be that something is shorting out and causing a slow drain on the battery?
Can a problem with a safety sensor cause both the blade disengage issue and the dead battery issue?
Thanks in advance.
Jim

 
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09-23-17, 04:34 PM   #2  
Is the mower deck vertical location the same when starting the engine (blade disengaged) and when disengaging the blade after mowing?

 
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09-23-17, 11:23 PM   #3  
There isn't anything electrical that would cause that problem unless the battery is getting so low that can't keep the fuel solenoid open. I'd try loosening the gas cap and see if it straightens out. If not, you may need to check flow into the bowl of the carb. It could be a collapsed fuel line.


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09-24-17, 07:37 AM   #4  
Is there any smoke when it does this? The only thing that makes any sense to me is if it running rich enough to be ok under load then too much when load is removed.


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09-25-17, 05:24 PM   #5  
I agree that it may be running too rich.


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09-28-17, 10:40 AM   #6  
Thank you

Thank you Beelzebob, Cheese, &amp; BFHFixit for the help.<br />
<br />
Beelzebob, the mower deck is usually, but not always at the same vertical height when I start the tractor as when I disengage the blades. Should I experiment with differing heights?<br />
<br />
Cheese, I had tried loosening the gas cap as the engine began sputtering with no apparent success. I tried loosening the cap now because years ago this tractor would stall and I found at that time the hole in the vent cap was plugged. Clearing the vent hole solved the issue then, but doesn't seem to help now.<br />
<br />
BFHFixit, I'm not sure if there was smoke or not. I have had times in the past when after shutting the tractor off for only 10 minutes or so, and then starting it up, it would backfire. Is this also a clue the engine may be running too rich. I tried to adjust the mix, but found I didn't recognize the configuration of the carburetor. It was different than the one on a previous Briggs engine I used to have.<br />
<br />
I'm attaching four photos and would appreciate any advice on how to make adjustments so that the engine isn't running too rich.<br />
<br />
Thanks again in advance.<br />
Jim

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Last edited by jyoung1952; 09-28-17 at 10:45 AM. Reason: corrected a spelling error
 
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09-28-17, 06:21 PM   #7  
Have you had the bowl off the carburetor recently? Does the black lever on the carb return to it's original position by itself when you move it and let go?


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10-07-17, 01:10 PM   #8  
Answers to Cheese's questions

Sorry for the slow reply. I went away on a week long fishing trip and have just returned. Here are the answer to the questions Cheese asked:
1. No, I have not had the bowl off the carburetor recently?
2. Yes, the black lever on the carb does return to it's original position by itself when I move it and let go?

 
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10-07-17, 01:35 PM   #9  
Un-attached wires

I removed the gas tank to clean out the dried grass clipping that had accumulated there. I discovered two wires (one with a red plastic casing and the other with a blue plastic casing) that were not attached to anything. I thought maybe this was the cause of the engine die-ing out, so I checked to see if they would fit together. With a slight bit up stretching, they did. Once attached, I tried to start the tractor to see if this fixed the problem. The tractor started fine, I mowed a while, and then disengaged the blades, and the engine died out as before. So I un-hook the wires and took the picture I have attached. I drew a yellow-green circle around the ends of the two wires.
Any thoughts on the matter? Should there be wires that aren't attached to anything? Should I leave them apart or put them back together?

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10-07-17, 07:06 PM   #10  
Can't tell where they go, but it looks like the lower one goes to the solenoid? If so, it looks like the upper one is the wiring harness system ground. If it works with it unplugged and my guesses are correct, then the solenoid is internally grounded at the mounting bracket, so it won't matter if they are connected or not.


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10-08-17, 01:36 PM   #11  
running too rich?

Okay, two of you have said that it may be running too rich. Please give me instructions on how to make it run less rich. Are the carburetor pictures I uploaded sufficient for you to use to explain the process?

Cheese asked if I have had the bowl off of the carburetor recently, but didn't say why he asked? Should I be taking it off?
Jim

 
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10-08-17, 02:36 PM   #12  
The black lever is your choke, make sure it opens completely and the throttle cable is adjusted correctly so as to no keep it open some at full throttle. The other thing that could make it run rich is a leaking needle valve, possibly a head gasket.
Easiest way to check is to check the spark plug, if it is running rich the plug will be black and sooty.
I believe you have a manual PTO? so there should be no electrical causing this.


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10-08-17, 04:55 PM   #13  
choke, plug, & sensor

Again, thank you for the help.

This is a reply to BFHFixit:

I just looked at the choke. It appears to be working correctly. Closed when the throttle is set to 'choke' and open at 'full throttle'.

I took the plug out. It is black, but I didn't have any soot rub off on my finger when I touched the end

You are correct about the tractor having a manual PTO. I had originally asked about a possible electrical issue because my past experience with getting off of the tractor while it is running. When I set the parking brake, I can get off of the tractor seat and it will stay running. However, when the blades are engaged, the tractor immediately shuts off when I lift off the seat even if the parking brake is applied. So I assumed there is a safety sensor that detects whether the blades are engaged and I had thought perhaps this sensor was faulty.
Thanks,
Jim

 
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10-08-17, 05:41 PM   #14  
Very weird, remove the mower deck and see how it runs, probably the wind from the spinning blades is keeping a wiring problem covered up. Have a good one. Geo

 
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10-10-17, 12:03 AM   #15  
Check your oil, does it smell like gas?

I asked if you had the bowl off recently because there is a gasket that could come out of place and a jet that can fall out easily if the carb is opened. Either could cause it to run rich. One would cause it to leak all the time most likely.


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10-16-17, 07:50 AM   #16  
Oil doen't smell like gas

Cheese: The oil does not smell like gasoline. It doesn't leak gas from the carburetor. Isn't there a screw on this carburetor for adjusting whether the engine runs rich or lean? If so, is it one of the screws shown in the photo I posted? Is so, which way do I turn it for less rich? Do I turn it 'in' (right) for less rich? By how much should I first try?

Geogrubb: I haven't yet tried running the tractor with the mower deck off. I currently have the cowl and gas tank off to get access to the carburetor. I'll try your idea once it's put back together.

Thank you both,
Jim

 
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10-16-17, 05:15 PM   #17  
Check your valve clearances.Don't adjust them, just check and report the clearance. I'm thinking you've got a lobe worn nearly off of your camshaft.

Your carb has no adjustment for high speed fuel mixture.


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10-18-17, 05:20 PM   #18  
Running Too Rich

All of a sudden this has gotten way "out of my league". I have no idea how to "Check your valve clearances. Don't adjust them, just check and report the clearance. I'm thinking you've got a lobe worn nearly off of your camshaft." Is this still in regard to your thinking that the engine is running too rich or have you dropped that idea and are saying that you feel there is a whole different issue? Is having a worn lobe consistent with the fact that I can mow for an hour or more with the tractor operating fine?
I could handle adjusting a screw on the carburetor for attempting to make the engine run less rich, but may need to take the tractor to a professional regarding checking the valve clearances. Is checking valve clearances easier that I am assuming? Are any special tools required? How likely do you think it is that there is a worn lobe causing the problem of the engine stalling when the mower deck blades are dis-engaged?
Jim

 
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10-18-17, 09:26 PM   #19  
No, sorry, disregard my previous reply as I was not considering all the info. The thread is too long to re-read it all every time and I had forgotten that it was when you DIS engage the blades. I was thinking of it being when you engaged them that it dies.

Check the wires that come out from the top of your engine near the starter. Make sure that they are not pinched behind the starter, between it and the engine block. I've seen that before and when the engine gets warm the ground wire for the ignition coil will begin to leak current through the smashed insulation to the block and cause the engine to sputter and run badly and die. It doesn't explain why it does it when the blades are off, but worth checking since your problem is not run-of-the-mill anyway and the obvious culprits have been checked off the list.


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10-19-17, 02:03 PM   #20  
No, there are no wires between the starter motor and the engine block. All wires are free and clear.

Are we still working on the assumption that the engine is running too rich? If so, no one has offered any advice on how to make it run less rich? Is there a screw on this carburetor for adjusting whether the engine runs rich or lean? If so, is it one of the screws shown in the photo I posted on September 28, 2017? Is so, which of the screws and which way do I turn it for less rich? By how much should I turn it at first?

In case it gives further insight to the issue, here is a report of the last two days. Yesterday, I used the tractor to mow with the same result as before. After I finished mowing, the engine died out when I DIS-engaged the blades. Today, I didn't do any mowing. I just used the tractor to pull a grass/leaf sweeper. It ran fine for about 30 minutes and then suddenly shut down. It re-started right away, but shut down after about 5 minutes and would not re-start. I waited about and hour and it then started right up. It ran for about 30 minutes and then shut down. Again, it wouldn't start until I waited about an hour. Does this give any further clues?

As always, thanks for the help,
Jim

 
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10-19-17, 03:16 PM   #21  
There is no real adjustment on that carb. The screws in the pic, the bare one is idle speed and the encased black one (if functional) would be idle mixture IIRC. About the only things that would cause it to run rich is dirty/plugged air filter, partially closed choke maybe a leaking needle valve.
Perhaps dis-engaging the blades is merely a coincidence rather than a symptom. When it dies out and will not restart, check for spark. You might have a magneto/coil going out. If you have spark and it will not start, try a dribble of gas in the carb.


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10-19-17, 03:27 PM   #22  
I just looked at the parts manual and while it doesn't state it, is this perhaps a Briggs Intek?
It looks to be and these are prone to blowing head gaskets across the thin area between the cylinder and the pushrods as there is not bolt there. The ones I have seen show a rich condition on the spark plug and sometimes will blow black smoke. This is because if it blows across where the intake valve is, fuel is still sucked into the combustion chamber when the intake valve is closed. I would still check for spark at least when it won't start or you might just want to pull the head and have a look. It's not really a big job at all.
If you have any mechanical ability at all and a few tools, standard sockets, and maybe a torx set, we can walk ya through it.


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10-20-17, 10:57 AM   #23  
Dying regardless of the blades being on or not makes a lot more sense. What you just described sounds more like a failing coil than a rich condition. The rich condition was partially settled on because we thought it was only dying with the blades off. As for offering advice on how to make it not run rich... that's what all the discussion about fuel in the oil and having the carb bowl off, etc... was about. Trying to find out why it might be running rich. It's not as simple as just turning a screw or we'd have mentioned that long ago. Check for spark when it won't restart.


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10-20-17, 07:29 PM   #24  
Sorry, I should have figured out that if it had been as easy as turning a screw, one of you would have said so.

I'm pretty good mechanically when I understand what I'm doing. Where I'm lacking in mechanical ability is in the understanding of the terminology. For instance, when BFHFixit said "You might have a magneto/coil going out." is that the same as when Cheese said "sounds more like a failing coil"? Also, when you asked about my mechanically ability and walking me through it, was that in regard to repairing a failing coil or to repairing a blown head gasket or both?

I'm assuming here that the answer to my question above regarding the magneto/coil going out being the same as the coil failing is a 'yes'. With a failing coil, is it typical that an engine could run for 30 minutes, stall out, not start immediately, but then start after cooling down for an hour?

I have all sizes of sockets and smaller sized torx bits. I would have no problem with buying larger size torx bits if needed. I don't know whether the engine is a Briggs Intek or not. If it is, would it say so somewhere on the engine? The next time it stalls out, I'll check for a spark. Is checking for a spark to help determine whether the problem is a failing coil or a blown head gasket?

I would like to use the tractor for fall leaf clean up. Can I cause greater harm by using it before it is fixed?

Again, thank you for you help and your patience,
Jim

 
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10-20-17, 09:01 PM   #25  
Coil and Magneto are the same term used in small engines. There is actually a difference but I won't divulge that now other than to say that most small engines actually use a Magneto unlike a Coil which is more automotive type ignition.
It is typical for a Magneto to fail like this when it heats up the stacks can short or open failing to provide spark. When they cool down they might again work.
The magneto is in one of your pictures, it is what the high tension lead comes from that goes to the spark plug. It is mounted next to your flywheel.

I have seen these head gaskets cause similar problems but not to point of where they would die then start and run again. Usually they will run fine for a while then sputter and blow black smoke, then might be good again when cool...etc.

Verify you have spark when it dies on you, try the dribble of gas if you have spark and no start then we can go from there.

Intek is usually printed on the shroud somewhere but I am certain it is the same weak area after looking at the IPL. Pretty much all that is needed to remove the head and set the valves is 3/8" 1/2" sockets, I think T25 torx and a 10mm wrench and feeler gauge, pencil or wood dowel or some such to find TDC.


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10-22-17, 01:12 PM   #26  
Thanks. I think I understand all of this except where you said looking at the 'IPL'. I'm re-uploading one of the original photos with what I think is the magneto circled. Am I correct? Also, am I correct in that you are thinking that the problem is more likely to be the magneto failing rather than a blown gasket?
My plan is to use the tractor for leaf cleanup in the next couple days. When it stalls out and will not restart, I will check to see if the is a spark. If no spark, it will point to the magneto as the problem. If there is a spark and a dribble of gas in the carb makes it start, then we're looking at a fuel system issue rather than a magneto issue. Am I on the right track here?
Am I likely to cause further damage to the engine using it this way?

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10-22-17, 08:05 PM   #27  
Yes that is the Mag and no you won't cause any damage using it.


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10-23-17, 10:02 AM   #28  
Thanks.
I was using the tractor today and it stalled multiple times, but always restarted again. Then it rained, so I didn't check for a spark. I assumed if it restarted, it had a spark.
Back in the house, I was curious of the price of a new magneto so I went online. I found part no. 591459 (replacement for part no. 492341) for $59.23 at searsparts.com and $35.27 on Amazon for genuine Briggs & Stratton, Does that sound about right?

 
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10-23-17, 11:13 AM   #29  
.


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10-28-17, 01:18 PM   #30  
Okay, I'm getting confused again. You had me convinced that the engine dying out when the blades were disengaged was just coincidental, but after yesterday, I'm not as sure. I was using the tractor, with blades engaged, to chew-up/mulch leaves while at the same time pulling a grass/leaf sweeper, Once the sweeper was full, I dis-engaged the blades to pull the sweeper about a block down the street to a place where people in my neighborhood have a compost area. Before reaching the compost place, the engine sputtered and stalled. Because it re-started, I was able to dump the clippings and head back towards home. Before reaching home, the engine sputtered and stalled again. Again, it re-started and I made it back home. Once home, I re-engaged the blades and mulched and swept leaves again until the sweeper was full. Then the process repeated itself two more times. The engine stalled, but re-started when towing the sweeper without the blades engaged, but never stalled while the blades were engaged. Each of the six times the engine stalled, the blades had been dis-engaged. Because the engine always re-started, I never pulled the spark plug to check for a spark.
Any new thoughts? Are you still thinking magneto? Should I order and install a new magneto and see if it solves the issue?
Thank you again,
Jim

 
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10-29-17, 12:44 PM   #31  
Did the engine surge up and down before stalling?


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10-31-17, 05:00 PM   #32  
Not 100% sure what surging up and down means, but if it means the engine revved up and down, then yes.
In case it's a clue to something, the daytime high temperatures are at least 30 degrees colder now than when I originated this post. The engine seems to stall less often in the colder weather.

 
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10-31-17, 06:31 PM   #33  
Yes that is surging, and I believe cheese might be alluding to some crap floating in the float bowl and causing a fuel restriction from time to time. Fuel filter or fuel lines could also be suspect.


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11-01-17, 06:45 PM   #34  
I checked the fuel filter and fuel line back before I first posted and they were clear at the time, but I'll check them again. If those are still clear, I'll give the float bowl a try. It's been a decade or two since I've removed a float bowl, so I'd appreciate any advice. The last time I removed one, there was no solenoid, just a screw at the bottom of the bowl. I'm confused because the schematic in my owners manual shows both a screw (#950) and a solenoid (#947) under the bowl, but not how they attach. Any advice please? Should I be able to remove the bowl without damaging the gasket? If so, can I reuse the gasket?
Thanks,
Jim

 
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11-02-17, 09:20 AM   #35  
I just checked the two sections of fuel line and the filter. Fuel is running freely through each of them. I also looked more closely at the float bowl. Unlike what the schematic shows, the top of the bowl has a flange with two phillips head screws. Looks like they hold the bowl on. Is that correct? <br />
1) Should I remove the solenoid from the bowl before removing the bowl from the carb? If yes, does it just unscrew? I assume I will need to disconnect the wire leading to the solenoid first.<br />
2) One of the screws that attach the bowl to the carb is on the side facing me and easy to access. The other is more on the engine side of the carb and harder to get at. Should I need to remove the carb from the engine in order to be able to remove the bowl from the carb?<br />
3) Are we ruling out the magneto as a likely problem or just leaving it until the float bowl is checked?<br />
As always, thank you,<br />
Jim

 
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11-02-17, 10:45 AM   #36  
If it's surging then your problem is 100% related to lack of fuel . It could be water, could be trash, could be improper tank venting, trash in the bowl, bad lines, an air leak that opens up when hot (unlikely) etc...


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11-02-17, 03:13 PM   #37  
Rather than removing the float bowl, would it do any good to remove the solenoid and flush out the float bowl by running fuel in through the fuel line and draining it out the solenoid hole?

 
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11-02-17, 04:35 PM   #38  


Once you have it down this far you may as well do all the way. Pinch/plug the fuel line and remove the two bolts at the intake then you can unhook the throttle linkage and the choke rod just pulls out of a slot, then you can take it to a bench remove the screws for the bowl, get a can of carb and choke cleaner and clean it all up. I don't know if yours has the plastic transfer tube or not but you can spray through the main jet and welch plug. Also remove the air filter adapter and in the throat you should see a couple of holes to spray through.
While it's off spray and clean the solenid as well exercising the plunger.
Keep track of the O-ring/gasket for the intake put it back together and see what ya got.


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11-03-17, 09:01 AM   #39  
Thank you for the very thorough reply. I think I understood everything up to the point where you said "spray into the main jet and Welch plug". I have never heard of a Welch plug so I Googled it and watched a YouTube video about how to remove a Welch plug. Are you suggesting I remove the Welch plug or just spray into the small hole on the inside of the carburetor?

 
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11-03-17, 11:43 AM   #40  
This thread needs to be terminated and re-opened, no one is going to read 40 posts to find there is a carb problem since the Title states something totally different. Have a good one. Geo

 
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