Go kart engine start failure

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  #1  
Old 12-04-10, 07:30 PM
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Go kart engine start failure

I have acquired an old go kart from my friend today to fix up and use for myself. I knew the engine wasn't working so i looked through (complete disassemble) and have determined that it should be running. I tested the spark and i did get one when i had the spark plug out with a spare plugging the hole without issues, but it didn't start. I looked though the carb and i believe it should be working. When i took out the spark plug after a few futile pulls i could not smell any gas in the cylander. Should I a)try to start it with full throttle b)clean out the carb or c) something else?
 
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  #2  
Old 12-05-10, 06:16 AM
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You did not say anything about what type engine you have so we're pretty much in the dark, and if your have completely disassembled the engine then now the problem could be almost anything. I usually save disassembly as a last resort. With an engine that has not run for a while I focus on the carburetor and fuel system (tank, fuel lines, shutoff valve). Does your cart have the fuel tank mounted on top of the engine or is the fuel tank mounted somewhere else on the cart or lower than the carb? Do you feel the engine develop compression when you pull the start cord?
 
  #3  
Old 12-05-10, 06:24 AM
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If you have good spark, the next step should be to give the carb a little shot of gas and see if it tries to start/run.

What is your definition of a complete disassemble?
 
  #4  
Old 12-05-10, 08:38 AM
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I do feel the engine devolop a compression and I know the fuek line works. The gas tank is mouted above the engine to the side. I know gas is getting to the crd because it is pooling were it should be but ill clean the carb today and see if I can get it started.
 
  #5  
Old 12-05-10, 06:29 PM
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Complete dissasemble= take out every nut/bolt and seperate all of the pieces and them put back together. I did this because i couldn't see why the engine wasn't starting. Also, how would you apply a shot of gas to a card.
 
  #6  
Old 12-06-10, 05:05 AM
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It depends on how the carb sets on the motor. Generally you'd just pour a small amount of gas in the carb. On my grandson's go kart the carb is mounted sideways so back when I was having problems with his - I poured a little gas in a clean squirt bottle and gave it a shot that way.
 
  #7  
Old 12-06-10, 05:13 AM
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Where would I apply the shot, through the fuel line, into the pool, where?
 
  #8  
Old 12-06-10, 05:24 AM
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Take the air filter off of the carb and add gas directly into the carb. You don't want to add much gas, maybe a spoon full. If it runs for a few seconds - you know you have a fuel issue and check out the tank, fuel line and even the carb.
 
  #9  
Old 12-09-10, 11:42 AM
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Simple causes for gokart not starting

Identifying the gokart make/model and engine would be helpful. But here's a couple of tips on things I've found.
On some gokarts there are 2 kill switches - one on the engine and one located usually on the steering wheel that toggles the engine ON-OFF;
There might also be a in-line fuel valve that needs turned to allow fuel to reach the engine which you didn't mention;
Check the choke-control mechanism; on my gokart it was a solid core piece of pre-formed wire that the choke-control lever operated that had gotten deformed and was not actually performing its job;
Take off the air filter to check the choke-plate operation and while the filter is off, spray some coldweather start fluid (ether) onto the carb and try starting immediately.
Good luck and let us know what you find.
greynold99
 
  #10  
Old 12-09-10, 04:35 PM
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i have bypassed the switches and there is no choke on the engine. As of now there is no spark. Would moving the magneto closer to the flywheel help get a spark or a better one? Also, what is the liquid that you would use to clean a carb? Were can i get ether and the liquid that one would use to clean a carb?
 
  #11  
Old 12-10-10, 06:48 AM
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I'm not trying to bash you, but your first step (totally disassembling and reassembling the engine) was a very advanced move and now you are asking very basic questions. You still have not said what engine you are working on (make, model, serial number). Is this a joke?
 
  #12  
Old 12-10-10, 01:07 PM
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Well, i haven't said the model number yet because i haven't found it yet, so i was asking general questions as to what i can do. As for dissembling the engine i did that out of curiosity and i did reassemble it so that everything is working but the spark right now, which is the mystery, since it is grounded (i think, i need to double check my connections) and the magnet on the flywheel is good. Would moving the magneto closer to the flywheel generate a better spark (if one at all)? I'm going to see if i can find the model number now so i will get back to this post as soon as i do. And no, this isn't a joke.
 
  #13  
Old 12-10-10, 01:15 PM
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How do you know everything was reassembled correctly?

You originally said you had good spark, what changes [if any] have you made since then?
 
  #14  
Old 12-10-10, 01:46 PM
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I really have no idea. The system for the spark i avoided when I was taking apart the engine and is more or less completely separate from the engine block so i really have no idea. I did test with a spark plug that i knew worked and that didn't get a spark so it must be the magneto.
 
  #15  
Old 12-10-10, 01:50 PM
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Also, the model a tecumseh powersport ohh50 in the 2tpxs.1721aa family spec: 68133h
 
  #16  
Old 12-13-10, 04:19 AM
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If you don't have feeler gauges to set the coil gap you can use a business card between the coil and flywheel as a spacer. The card should not be pinched tight but it should be a bit snug. Don't forget to tighten the coil's bolts.
 
  #17  
Old 12-18-10, 06:06 PM
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well, i have done all of that and i get no spark at all. What would be a step by step to get a spark?
 
  #18  
Old 12-18-10, 07:14 PM
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I would look at every part of the ignition system. Pick an end (say the spark plug for example) and work through the system from end to end checking everything. Sometimes it's something as simple as the core of the spark plug wire not making contact inside the spark plug boot.
 
  #19  
Old 12-24-10, 11:58 AM
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No matter what i do to get a spark i cant. I even referred to a different small engine to see if the wiring was right, which it was. What is wrong?!
 
  #20  
Old 12-24-10, 02:55 PM
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Check everything and I mean everything. Even check the stupid stuff.

I assume you've tried putting the plug wire on the spark plug, hold the plug against the bare metal of the engine and gave the starter a good pull and saw no spark.

Is the flywheel turning?

Is there a magnet in the flywheel?

Use a business card as a spacer to set the gap between the coil and flywheel.

If there is a small wire coming from the coil, disconnect it. Try seeing if you get a spark with nothing in the loop but the coil, spark plug wire and spark plug.

Try to remove the spark plug boot from the end of the spark plug wire. You should be able to pull hard and/or give it a twisting motion. You should then see the core of the spark plug wire. Remove the spark plug from the engine so you can easily pull the cord. Hold the bare end of the spark plug wire really close to bare metal of the engine and pull the starter cord. Do you get a spark?

Remove the coil and make sure there is not a lot of rust or dirt on the mounting pads and bolt to make sure the coil can make good contact with the engine block.

If you are still not getting a spark the coil is bad or the spark plug wire is broken/open inside. In either case it's the same part and I guess it will probably be $35-$45.
 
  #21  
Old 12-24-10, 03:54 PM
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Heres the thing, If i hold the end of the spark plug wire (which i know isn't the brightest of ideas) i do feel an electric shock, though not quite as painful as the ones that i have received from engines that run. I know that I am grounded so that means that the ground wire is not. How should I wire the spark plug? I believe that I have given you the model number of the engine. If possible, the simpler the better because once i have a working circuit i know how to install kill switches in it.
 
  #22  
Old 12-25-10, 06:23 AM
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Oh good you have a working coil. I was afraid to mention holding the end of the wire. It's a pretty reliable test for some kind of spark but even turning the engine slowly by hand you still can get a decent poke.

All you have to do it connect the wire in the center of the spark plug wire to the very top of the spark plug.

The rubber spark plug boot can sometimes be a problem. For many style you simply shove the spark plug wire into the boot, though some you twist/screw the boot on. Up inside the boot there is a pin that should shove into the core of the spark plug wire making the electrical connection. Making a fresh cut, removing about 1/4", on the end of the spark plug wire sometime helps by giving the boot fresh wire to bite into. Since it's not a soldered or crimped connection corrosion sometimes grows between the spark plug wire core and the spark plug boot. As the corrosion grows it slowly weakens the electrical connection and the spark at the plug gradually gets weaker and weaker until it no longer works.
 
  #23  
Old 12-25-10, 08:11 AM
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I was more concerned as to how to ground the spark plug. how should I?
 
  #24  
Old 12-25-10, 02:02 PM
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well, i figured out how to ground it but another problem has arisen; i cant get the fuel that i have poured down the spark plug hole to ignite unless i use a cordless drill to spin the axle ( a pull cord isnt fast enough?). What could i do to resolve this?
 
  #25  
Old 12-25-10, 07:21 PM
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You seem to be inexperienced at engine repair and you totally disassembled & reassembled the engine. Problems are to be expected.
 
  #26  
Old 12-25-10, 07:31 PM
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Know tht I am inexpierenced but I learn fast and once I have done something I know to do it again. I know everything works, the valves the go up and down in time and I get a spark. What can I do to help the engine spark with a pull cord other than making a smaller gap in the spark plug unless that is the right thing to do?
 
  #27  
Old 12-26-10, 10:32 AM
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Well, there is no problem with the spark plug or anything roght now, so all there is to do is to attach a gas tank and see if it starts.
 
  #28  
Old 12-26-10, 03:20 PM
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The engine is designed to start with the weaker spark generated from a hand pull start so if everything is right is can work. Post back with what happens when you try to start it.
 
  #29  
Old 12-27-10, 09:58 AM
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well, i tried to start it but it didn't go. I tried starting it with a drill again but nothing happened. I took off the exhaust and smelled it and it smelled like gas but not as strong as it probably should. I think it has come down to one of three possibilities; 1. The carb is clogged? 2. The manual pump isn't working? 3. A valve is maladjusted? What should be the process to figure this out?
 
  #30  
Old 12-27-10, 10:13 AM
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Here is a link to look at what i got for a carb: Parts and Diagrams for Tecumseh TEC-640017B
 
  #31  
Old 12-27-10, 11:31 AM
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Does the engine run a second if your put a teaspoon of gas in the spark plug hole (re-install the plug before trying to start it)? If so, then it is possibly a carburetor problem. If it will not run or try to run then you could have something wrong with the ignition or a problem inside the engine like the cam & crank shafts not timed/aligned. You could also check the valve gap but even if the gaps are pretty far off it should still make a good attempt at running. Also insure that there is a key between the crank and flywheel and that it is perfectly square with no jagged sides.
 
  #32  
Old 12-27-10, 12:23 PM
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also, i put gas in the tank and when i took out the ajustment knob for the idle no gas spilled out, so im guessing that the idle jet might be clogged as well.
 
  #33  
Old 12-27-10, 12:35 PM
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Gas will not pour out of the high or low speed jets. The bowl, float & needle valve below the carb hold the fuel at a very specific level. Then air flowing through the carburetor sucks (venturi) the fuel up into the jets. There is only fuel up in the jets when the engine is turning/running.
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This is why the fuel level in the bowl is so important. If the level of fuel in the bowl is too low the venturi effect is not strong enough to suck fuel up through the jets. If the fuel level is too high fuel may pour out of the jets flooding the engine.
 
  #34  
Old 12-28-10, 09:45 AM
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I was turning over the engine today with the cordless drill and when i took off the air filter i notice that there was gas coming out of the main jet and when i was priming it there was gas coming out of the main jet. This has led me to believe that the problem must be interal, as in the gap for the spark plug isn't wide enough or the valves aren't letting in enough fuel/air mixture, since when i looked at them (when i disassembaled the engine) they were sort of gunked up with black soot from everyday use. How should I procede?
 
  #35  
Old 12-28-10, 09:55 AM
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It could be a problem in the bowl of the carb (see the previous post). You should not see fuel just squirting out of the jets.
 
  #36  
Old 12-28-10, 11:13 AM
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again, that was when i was turning over the engine with a drill, but you are right and right now i have the adjustment valve on the carb wide open so i will adjust that to what may i ask? how much gas should i see coming out of the jets? Also, i have just realized that i may have maladjusted the overhead valves since i could have them too loose or tight. I have adjusted them now to (in the compression stroke where both are closed) to just enough pressure so they stay on the spring and let the valve close all the way. I tested the alignment by putting a piece of paper towel next to the opening of each valve, turning it over with a drill, and the carb intake was sucking in the paper and pushing it out a little (the carb is the compression release) and the exhaust valve was only pushing the paper towel away. Is there a way to make sure i have the alignment right?
 
  #37  
Old 12-28-10, 11:34 AM
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I think both the intake and exhaust valves should have .004" gap between the valve and rocker arm. This is measured and adjusted when the engine is at top dead center (TDC). To find TDC remove the spark plug and valve cover. Slowly turn the engine watching the valves. On each revolution you will see the valves opening and closing the intake and exhaust strokes. You want to watch for both valves to be closed and the piston coming up. Stick a pencil through the spark plug hole and push it against the top of the piston. Slowly turn the crank and you will feel the piston come to the top and then it will stop. You can turn the crank backwards and forwards until you find the center of where the piston does not move. That is top dead center and where you should check the valve clearance.

Gently turn the carburetor jet adjustment screw all the way in until you feel it gently seat. Do not crank down hard or you will damage it. You just want to feel when it bottoms out. Then back out the screw 1 1/2 turns. That should be a good starting point. Once the engine is running you can fine tune it.

Back the idle speed adjustment screw (the screw that opens the throttle, butterfly in the carb.) all the way out. Then screw it in until it just touches the throttle arm. Then screw it in 1 to 2 turns more.
 
  #38  
Old 12-31-10, 02:41 PM
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if it helps i have adjusted the valves so that there is a .004" gap and i am definitively feeling a compression stroke (my drill will tell you that as well!). I have tried to start the engine and i have noticed a few things: 1. the engine will fire if i put gas down the hole (with the pull cord). 2. I cannot start the engine with the pull cord or drill. 3. I can see and feel the engine catch (sort of, as in it fires once every 5-20 revolutions) when i am trying to start the engine if i have the trottle all the way open. I will make your suggestions happen and extra advice based on what i have just given you would be much appreciated .
 
  #39  
Old 01-01-11, 12:37 PM
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done that and it hasn't started, even with the drill. What to do?
 
  #40  
Old 01-01-11, 03:27 PM
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well, further tuning has gotten me to a point were the engine turning over the engine sounds like (were n represents no firing and y represents a firing) nnnnnnnynnyynnnynnnnynnnynnnnnnnnnynnnnnynnnnyynnnnn... in a pattern like that. If i take off the air filter i can see a cloud of a fine mist of gas thats size is a little bit larger than a golf ball, if that helps. What should I do?
 
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