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Donald
Donald, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1800
Experience:  I have 25+ years of experience repairing 2 & 4 cycle engines
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My 12 year old scotts (john Deere) riding tractor started to

Customer Question

my 12 year old scotts (john Deere) riding tractor started to lose power at the end of an acre mowing job. power would start to die and then it would surge, producing black smoke exhaust. this would happen through a number of cycles. finally when I shut the engine off, I could not restart it. For point of reference fuel, fuel filter, air filter, and plug are all new. is it carb or fuel pump?
Submitted: 1 year ago.
Category: Small Engine
Expert:  Donald replied 1 year ago.
Hello and thank you for choosing Just Answer. My name is ***** ***** I will do my very best to get you the answer you need to your question.
What brand is your engine?
Customer: replied 1 year ago.
Intec / Briggs and Stratton
Expert:  Donald replied 1 year ago.
Thanks for this information. Do you have any carburetor cleaner in a can, or starting fluid? If so, spray a small burst directly into your carburetor, to see if your engine will start up briefly. This will confirm whether or not you are getting spark to your spark plug.
Customer: replied 1 year ago.
I have run out of both of those liquids and the stores are closed here now but it sounds like a good idea for tomorrow. If I get spark and it starts to pop over what then? Or if no spark I was going to pull the spark plug tomorrow morning and see if there was anything going on there
Expert:  Donald replied 1 year ago.
If your engine starts up and runs briefly, after you spray carburetor cleaner into your carburetor, this means you are getting spark to your spark plug. At this point, I would focus on a fuel or carburetor related problem. First check your fuel shut off solenoid, to see if it is working properly. It should click each time you cycle your ignition switch on and off.
Expert:  Donald replied 1 year ago.
There is a spring loaded plunger inside your fuel shut off solenoid. It must retract when your ignition switch is on, to allow fuel to flow throughout your carburetor.
Expert:  Donald replied 1 year ago.
Keep in mind that black smoke is a sign of your engine running rich. So , if all of the previous tests passes, then check your carburetor. It may need a really good cleaning.
Expert:  Donald replied 1 year ago.
Also check your valve clearances.
Expert:  Donald replied 1 year ago.
If you determine that you are not getting spark to your spark plug, remove the cover from your engine, and then remove the small black kill wire from your ignition coil. Spin your engine over again, with your kill wire off of your ignition coil, and check again for spark. If you still do not get a spark, then your ignition coil is at fault.
Customer: replied 1 year ago.
In taking the air filter off I noticed inside the engine a very fine wire spring looks to be on connected on the other end could this be the problem? What is this spring called?
Customer: replied 1 year ago.
I mean the spring is unconnected
Expert:  Donald replied 1 year ago.
This is your governor spring. It will not prevent your engine from starting.
Customer: replied 1 year ago.
There are two springs involved here are you sure that fine wire one will not make any difference?
Expert:  Donald replied 1 year ago.
What are the model, and type numbers for your engine? I would like to take a look at a break down of your engine. That spring does need to be attached on both ends, but your engine should at least start up without it attached.
Customer: replied 1 year ago.
It started on its own this morning without me doing anything to it. However after I shut it off and tried to restart it it would not start again. Thoughts?
Customer: replied 1 year ago.
It is model number L 1742 the engine serial number is ***** f 707 011 ze1
Customer: replied 1 year ago.
When I tried to restart it it looked like it was shooting gas vapor up through the carburetor air intake area
Expert:  Donald replied 1 year ago.
How long did your engine run before you shut it off? We need to determine if you are getting spark to your spark plug, during the times when your engine will not re-start.
Customer: replied 1 year ago.
The engine ran less than 30 seconds before I shut it off
Customer: replied 1 year ago.
Just a note before I started the engine this morning I did not use any carburetor cleaner or starting fluid to get it going
Expert:  Donald replied 1 year ago.
Can you check to see if you are getting spark to your spark plug?
Customer: replied 1 year ago.
Yes I just pulled the spark plug and ground is it and turned it over and I got a brilliant consistent spark however when I pulled it it was quite wet
Customer: replied 1 year ago.
It also looked like I was getting quite a bit of gas vapor blowing out of the spark plug hole so it looks like atomized fuel was being dispensed into the cylinder
Expert:  Donald replied 1 year ago.
Are you familiar with checking your valve settings? Based upon what we have discussed so far, your valves very likely needs to be adjusted.
Customer: replied 1 year ago.
Do you mean the intake and exhaust valves?
Customer: replied 1 year ago.
Where would I get the information to what to adjust them to?
Expert:  Donald replied 1 year ago.
Yes, I am referring to your intake and exhaust valves.
Intake Valve = .003"-.005"
Exhaust Valve = .005"-.007"
You will check and adjust your valves, when your piston is 1/4" past top dead center, on your compression stroke. Both valves should be closed at this point.
Customer: replied 1 year ago.
I found a YouTube video explaining how to do this in detail to my Briggs and Stratton engine I'll do this shortly the engine has over 400 hours on it and I've never done this maintenance procedure.
Expert:  Donald replied 1 year ago.
Thanks for letting me know. Take your time, and you should be able to accomplish this task. Start by checking your valve clearances first, to confirm if your settings are out of spec., then go from there.
Let me know what happens.
Customer: replied 1 year ago.
Hi I adjusted the valves but they weren't off very much to begin with and now I still can't start the tractor they were very clean inside a couple of bolts were loose on the valve cover but that's all
Expert:  Donald replied 1 year ago.
Did you get a chance to purchase a can of carburetor cleaner? If not, put about a teaspoon of fuel into carburetor to see if your engine will start.
Have you checked your fuel shut off solenoid?
Customer: replied 1 year ago.
Yes I purchased the can of carburetor cleaner but have not spread it into the carburetor opening yet. I have not checked the solenoid because I wasn't sure how to do that procedurally as well as locate the solenoid
Expert:  Donald replied 1 year ago.
Okay ...
Customer: replied 1 year ago.
Spray the carburetor cleaner in the intake hole but was still unable to start the tractor I'll have to check the solenoid on Monday this is Been a much bigger project than i realized
Expert:  Donald replied 1 year ago.
Thank you for letting me know. On Monday, check to see if you are still getting spark to your spark plug. Please keep me posted on your progress.
Customer: replied 1 year ago.
hi Donald I was able to start my mower today I changed out the spark plug the new one that I had put in fell apart so I put the old one in Regapped it. however the mower runs extremely uneven and very rich black smoke I was able to cut the lawn and it got better as I did it more but it still is not running right any suggestions
Customer: replied 1 year ago.
you mention that if I was running very rich the carburetor might need a good cleaning how far do I go with this and how to do I take it apart?
Expert:  Donald replied 1 year ago.
I will be away from my computer until after 5:00 pm central time today. I can assist you at that time. I am replying to you via my mobile phone.
Customer: replied 1 year ago.
some of the symptoms point into a blown head gasket. how can I diagnose it without taking the engine head off whether this is so? I've seen some blown head gaskets on the YouTube videos for my model engine that from visual inspection do not look blown.
Expert:  Donald replied 1 year ago.
To check for a blown head gasket, you will need a tool called a Leak Down Tester. Remove the fuel bowl from your carburetor, to see if you have any sediments inside your fuel bowl.
Customer: replied 1 year ago.
okay I'll take the carburetor off and clean it tomorrow and see if that makes any difference
Expert:  Donald replied 1 year ago.
That will be great! Keep me posted on your progress. Thanks.
Customer: replied 1 year ago.
I am unable to figure out how to disassemble the carburetor to clean it. there are two bolts that hold it together and I was able to remove the nuts but I can't remove the screws even after pounding them with a hammerpossibly I can take the tank ball off but I need a special tool to unbolt the screw jet at at the bottom of the bowl.any suggestions for this type of special tool that I need?
Expert:  Donald replied 1 year ago.
The part you are calling a jet, is your fuel shut off solenoid. You will need a thin 1/2" open end wrench, to remove this part. I have ground down an inexpensive wrench to use for this purpose. After you remove your fuel shut off solenoid, you will be able to remove your fuel bowl.
I am not understanding which nuts you are referring to.
Customer: replied 1 year ago.
hopefully I will take the carburetor bolt off tonight and look at the bowl. I rented a compression checker and I had pretty good pressure in the cylinder about 90 to 100 pounds. Just wanted to let you know about that.
Expert:  Donald replied 1 year ago.
Thank you for keeping me posted.
Customer: replied 1 year ago.
hi Donald I ground down a wrench to remove the carb bowl looks fine I did not clean it. I also replaced the spark plug with an Autolite XS 3924 DP but now things are even worse the engine does not turn over just makes a buzzing sound where the starter is
Expert:  Donald replied 1 year ago.
As for the buzzing noise, check to see if your battery is still fully charged. Also remove your spark plug to see if your engine will spin freely with your spark plug out. After you remove your spark plug, check to see if there is any fuel in your cylinder, on top of your piston.
Customer: replied 1 year ago.
ok I'll get the battery charged up if need be tonight and see if I can run the engine with the spark plugremoved. how do I tell if the battery is not charged properly because it should still read 12 volts whether charged or uncharged correct?
Customer: replied 1 year ago.
I wanted to also tell you when I reconnected the wire to the solenoid on the carburetor there was a little spark before I fully connected it.
Expert:  Donald replied 1 year ago.
The spark is common if you attached the wire, when your ignition switch was on. If your starter is still humming after you remove your spark plug, then your battery could need to be charged. We just need to confirm that your engine is not locked.
Customer: replied 1 year ago.
I was able to rotate the engine by hand and I tested the battery it was at 12 volts so after a few attempts I was able to start the engine this morning and ran it for about 5 minutes I did not tested under power it seemed to run OK at high rpm but it wanted to sputter and die at low rpm. thoughts?
Customer: replied 1 year ago.
hi Donald good morning any other thoughts you might have on what to do about this engine lawn tractor engine of mine?
Expert:  Donald replied 1 year ago.
Thank you for this information. After you removed your fuel solenoid, did you go any farther with cleaning your carburetor? At this point, it will be great if you can remove your carburetor, disassemble it, soak it, and clean it thoroughly.
Customer: replied 1 year ago.
I'd be happy to do that but I'm unable to get the two bolts off that goes that hold the carburetor together I can get the nuts off but I can't get the bolts off what how do I do this?
Expert:  Donald replied 1 year ago.
I am not sure which two bolts are are referring to. I am attaching some carburetor information for you. Carburetor Information - Click Here
Customer: replied 1 year ago.
here is a picture (jpeg)of the two bolts that hold the carburetor together but I can get the nuts off but I can't get the bolt out.any ideas?
Expert:  Donald replied 1 year ago.
Take another look at your image. You can use a 7/16" socket to remove the nuts you are referring to. Be sure to remove your plastic engine cover first.
Expert:  Donald replied 1 year ago.
We can continue from here. Thanks!