QuestionQUESTION: My mtd mower model 13a6673g118 will not start.I replaced the carburetor a few years ago and it has been great for two years. About a month ago I started to have trouble starting it. It would take longer and longer to start it. I had the battery tested and it was fine. I put in a new spark plug and it started immediately but then next time nothing and it has been dead for two weeks. My original thought was the solenoid and safety switches but when I tested the spark plug, I had a blue spark. Does that mean the issue is not electrical and something within the engine? If so, what should my next step be? The engine will sometimes crank like its going to start but most times it does a half crank pause and another half crank (does that make sense?)
ANSWER: Have you dis-connected the battery cables and cleaned the battery posts and cable ends with a wirebrush? I've fixed a lot of starting problems just by cleaning the connections.
Since you have blue spark the safety switches are working properly. Does the oil smell like gasoline?
Can you send me the engine model, type and date code so I can look up which engine you have?
Eric
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wires
QUESTION: The engine is a Tecumseh OHV155-204509. The batery connections have been cleaned. I did try something after I emailed you. I wanted to see if I recieved a spark when I did not sit on the seat/ press in clutch (safety mechanisms). I was shocked and a little confused that I still had a spark on the spark plug. I also noticed that two wires were messed with (prior to me getting the mower). The wires were cut and then reattached. I am not sure why. I attached the picture.
ANSWER: Those wires look like the alternator wires. Is there a diode in the charging circuit? The link below will help identify the diode, see chapter 6.
http://www.cpdonline.com/692509.pdf
This link may help as well:
http://www.smallenginesuppliers.com/html/engine-specs/tecumseh/Tecumseh_quick_re
Before trouble shooting the electrical system we got to get the engine to start. Do you still have spark? If yes, then you still need compression and fuel. To rule out fuel, you can prime the engine with a small amount of fuel or starting fluid directly into the carb. If the engine tries to start then compression is fine and the fuel system if has issues.
Will the starter turn engine? If not, is the battery charged? We have to get the starter to spin the engine to continue trouble shooting.
The link below is the OHV service manual:
http://www.smallenginesuppliers.com/html/engine-specs/tecumseh/Tecumseh_4-Cycle_
Have you checked the valve clearance?
Let me know.
Eric
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QUESTION: Eric,
I have good news! I was able to start the engine. It was actually the best it has ever started. I just turned the key and it started immediately. I did a bunch a things to get it going so I am not sure what fixed it. I adjusted the valves to .004; new starter solenoid; removed starter and cleaned with sand paper; and changed the oil. It has never started that easily. What should I do about those wires. I checked with the lawn mower parts manual and there is no diode part mentioned.
AnswerCleaning the connections, even is just replacing the solenoid, will improve the circuit connections allowing more current to flow which results in more starter power.
Do you have voltmeter to verify the DC charging voltage. The purpose of the diode is to convert the AC current the alternator produces to DC current to charge the battery. If the battery is charging then there much be a diode somewhere in the circuit. I would just verify the DC voltage at the battery with the key off and then check with the engine running full speed. You should see a difference in DC voltage with the engine running. You should have at least 12 vDC with the engine running full speed.
Glad to hear the mower is running but I'd still like to know if the charging system is charging the battery.
Eric
