18 hp briggs twin, electical problems

Discussion in 'Mechanic and Repair' started by novatoasv, Mar 8, 2004.

  1. novatoasv

    novatoasv LawnSite Member
    Posts: 5

    have a 18 hp briggs twin. 92 year. have cleaned/tested 3 safety switches, deck, seat and ignition. all switches working ok, used meter to check for continuity. push
    down brake pedal, in neutral, try to start,
    nothing. took test light to verify current to solenoid post, 12.83 volts. battery also ok. heres the quandry. next i take a pair of jumper leads, black lead went to neg. post of battery and to black lead to meter set on volts. red jumper lead to solenoid post then to red volt ohm meter lead.
    turn the key AND ALL OF A SUDDEN THE ENGINE TURNS OVER. WHAT HAPPENED???? NOW MY PROBLEM IS FIXED. bad ground?? tested continity for ground at solenoid, mtg bolts and neg. battery to chassis ground all ok. please help. spent 3 hours double checking everything. thanks in advance
  2. sdwally

    sdwally LawnSite Senior Member
    Posts: 385

    Using your meter, check for voltage drop at solenoid. Connect neg meter to engine block, pos meter to battery cable at starter solenoid. Check voltage reading, then check voltage reading when cranking. If good, check for voltage drop on other side of solenoid. If reading drops you probably have a bad battery cable or solenoid.
    To check cables: Flex battery cables near each end of cables near terminals, if you find a soft spot, you have located your problem.
    Soft spots are corroded wires within the cable. Under no load you will get full voltage reading; under load, such as starting, the corroded spot will act as an open circuit.
  3. novatoasv

    novatoasv LawnSite Member
    Posts: 5

    thank you for your responce. these are areas i didn't check. positive cable from battery to solenoid is new. solenoid is a year or so old. i also cleaned the mounting area for the solenoid on the battery tray and applied dielectric grease. negative battery looked ok, from the exposed wires above the crimp connections, on both ends. didn't check the cable from solenoid to the starter motor. just that connection on the solenoid end visually looked ok.
    and btw- all of this only happened after washing the mower engine down with a pressure washer. i will check and verify/fix problems.

    also i had a bad cable problem on an old mustang once. come to find out the problem was a melted wire under the factory wiring/ wraped with tape. this was a very close but similiarl problem. thanks again in advance.

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