1987 Sundancer 300, engine will crank but won't fire up.

Discussion in 'Sport Cruisers' started by Brandon Baker, Aug 9, 2018.

  1. Brandon Baker

    Brandon Baker New Member

    5
    Aug 9, 2018
    1987 Sundancer 300
    Twin Chevy 350's
    Hello, I have a 1987 sundancer 300, with twin 350 chevy motors.

    One engine starts fine and runs good, The other engine has been giving me some trouble. So recently its battery would end up dying when we are out parked at the sandbar all day. In which cases I would use the emergency start switch and jump power from the other batteries. But recently now the battery doesn't die. The motor will just crank and crank and crank but will not grab and fire up. I replaced the starter because it was glowing red hot and shooting sparks when the key was turned. Didn't fix the issues. So i replaced the ignition coil, distributor CAP, still didn't fix the issue. We sprayed starting fluid into the carb and it still wont grab and fire.

    So its getting power from the batteries, its getting fuel, it has to be getting spark right? If the engine is cranking then its getting spark? I don't know I have a feeling it is something small and easy to fix and were just over looking it.

    Could it possibly be a fuse or something thats blown out that wont let the engine start but crank?

    Could it be a kill-switch possibly hidden somewhere that one of my drunk friends maybe flipped while on the water.

    I mean it cranking shows me a good sign that its wanting to start but just something small is not working.

    thank you for any advice you have, I am new to this big of a boat and twin engines.
     
  2. CliffA

    CliffA Well-Known Member GOLD Sponsor

    Dec 29, 2009
    Lake Norman, NC
    2001 Sea Ray 340DA
    Name: 'Happy Place'
    4.5kW West. Generator
    Purchased Nov. 2014
    Fresh Water Use
    Twin Merc. 6.2L (MPI)
    Raw Water Cooled
    V-Drive Transmissions
    just because the engine is cranking does not mean there is spark going to the plugs....it just means power is going to the starter...you can get a cheap spark tester like this at most auto parts stores or Walmart to confirm you have spark.....it goes between a spark plug and the plug wire.....while the engine is cranking there should be a light flashing inside the tester if there is spark present....

    cliff

    [​IMG]
     
  3. Brandon Baker

    Brandon Baker New Member

    5
    Aug 9, 2018
    1987 Sundancer 300
    Twin Chevy 350's

    Thanks for the reply cliff,

    So my buddy kind of tested it with a screwdriver to ground the spark and we turned the key and didn't see a spark from the spark plug wires to the ground. What is the fix for now spark in the wires?
     
  4. CliffA

    CliffA Well-Known Member GOLD Sponsor

    Dec 29, 2009
    Lake Norman, NC
    2001 Sea Ray 340DA
    Name: 'Happy Place'
    4.5kW West. Generator
    Purchased Nov. 2014
    Fresh Water Use
    Twin Merc. 6.2L (MPI)
    Raw Water Cooled
    V-Drive Transmissions
    you will need to back track the ignition system to see where the spark (if any) terminates....this will identify which ignition component is faulty.....

    it is a fairly simple system....

    the ignition coil sends spark to the distributor cap....the cap sends spark to all of the spark plug wires as the rotor button spins....the plug wires carry the spark to the individual spark plugs.....

    by the age of your boat your ignition system probably uses ignition points and a condenser inside the distributor cap.....my first thing to look at on this type system would be the ignition points....

    anyone fairly familiar with ignition systems should be able to troubleshoot this system relatively easily....

    good luck....
    cliff
     
  5. Bt Doctur

    Bt Doctur Well-Known Member

    Aug 21, 2010
    New Jersey
    Ex SRV 240 Weekender twin
    in between
    Try telling us what type of ignition system it is or post a engine serial number
     
  6. kap2

    kap2 Member SILVER Sponsor

    155
    Oct 28, 2013
    Rhode Island
    370 Sundancer 1998
    Twin 7.4L Mercruiser V-drive
    Check the 12v going to the coil. Do you know what the serial number of your engine is?
     
  7. Brandon Baker

    Brandon Baker New Member

    5
    Aug 9, 2018
    1987 Sundancer 300
    Twin Chevy 350's
    I do not have the serial # of the engines, only the serial # of the boat.

    But if it helps both engines are the Mercruiser Alpha one 260/V8

    The new one is a 2014 and that is the one that works

    The other is the original engine from 1987 and that is the one giving me problems.

    I am thinking that its not getting spark. Since we tried holding a wire to a screwdriver to a ground to check for spark and I don't recall seeing any. I am just unsure what to do if there is no spark.

    Let me get this right,
    So battery to Starter, Starter to ignition coil, ignition coil to middle spark wire in the distributor, distributor to each spark plug wire to each cylinder?

    So if this is the case, the starter is getting power because my old one shot sparks, but we replaced it. So now it is good, so the issue could be at the ignition coil, but I replaced it with the one on the engine that works and it didn't work. But the engine that doesn't work we tried that ignition coil on the engine that works and it started right up, so it can't be that right?

    Sorry for any confusion:D
     
  8. CliffA

    CliffA Well-Known Member GOLD Sponsor

    Dec 29, 2009
    Lake Norman, NC
    2001 Sea Ray 340DA
    Name: 'Happy Place'
    4.5kW West. Generator
    Purchased Nov. 2014
    Fresh Water Use
    Twin Merc. 6.2L (MPI)
    Raw Water Cooled
    V-Drive Transmissions
    let's slow down a little bit.....;)......

    maybe a little more detail will help...

    first off, the engine starter has nothing to do with the ignition system.....two completely different and separate systems.....

    there is 12V going from the battery to the ignition switch...when the ignition switch is turned to the 'run' position the 12V is routed to the ignition coil....the coil produces spark from the 12V supply....the coil sends the spark to the distributor cap via a coil wire....the rotor button inside the cap receives the spark from the coil...as the button rotates it delivers spark to the individual plug wires....the plug wires take the spark to the spark plugs....

    to troubleshoot start testing for 12V at the ignition switch....if there is 12V there then go to the next component in the system testing for 12V or ignition spark....keep going through each component until the 12V/spark stops....then you have found the problem...

    since the two engines are so different in age they likely will not use the same ignition coil....so swapping the coil from the good engine to the bad one will not help....

    cliff
     
  9. Brandon Baker

    Brandon Baker New Member

    5
    Aug 9, 2018
    1987 Sundancer 300
    Twin Chevy 350's
    Alright perfect, So I will need a Volt tester and go thru all the components you listed starting with where the power goes first?
     
  10. CliffA

    CliffA Well-Known Member GOLD Sponsor

    Dec 29, 2009
    Lake Norman, NC
    2001 Sea Ray 340DA
    Name: 'Happy Place'
    4.5kW West. Generator
    Purchased Nov. 2014
    Fresh Water Use
    Twin Merc. 6.2L (MPI)
    Raw Water Cooled
    V-Drive Transmissions
    you will need a voltmeter and a spark tester....be sure to set the voltmeter for DC volts.....

    I would imagine there are a lot of ignition troubleshooting guides on the internet to help.....

    cliff
     
  11. Brandon Baker

    Brandon Baker New Member

    5
    Aug 9, 2018
    1987 Sundancer 300
    Twin Chevy 350's
    Ok thank you for all the info. One last thing, and excuse my ignorance, but could it possibly be the rotor in the distributor has worn out and no longer arcs the spark needed to send spark to the plugs? Or would that be silly because it wasn't sparking with a screwdriver in the ignition coil plug in?
     
  12. CliffA

    CliffA Well-Known Member GOLD Sponsor

    Dec 29, 2009
    Lake Norman, NC
    2001 Sea Ray 340DA
    Name: 'Happy Place'
    4.5kW West. Generator
    Purchased Nov. 2014
    Fresh Water Use
    Twin Merc. 6.2L (MPI)
    Raw Water Cooled
    V-Drive Transmissions

    it is certainly possible that you have a bad rotor button.....but without testing you won't know for sure.....I suggest you do the troubleshooting to identify the bad component and not just randomly replace arts....that can get expensive....however, if it has been a long time since that engine had a tune-up it may be worth while to go ahead and tune it up with new distributor cap, rotor button, points and condenser (if applicable), plug wires and spark plugs......if that doesn't help I would look at the coil and the ignition switch....

    don't trust the 'screwdriver test' for spark....get the right diagnostic tools....

    cliff
     
    Brandon Baker likes this.
  13. CliffA

    CliffA Well-Known Member GOLD Sponsor

    Dec 29, 2009
    Lake Norman, NC
    2001 Sea Ray 340DA
    Name: 'Happy Place'
    4.5kW West. Generator
    Purchased Nov. 2014
    Fresh Water Use
    Twin Merc. 6.2L (MPI)
    Raw Water Cooled
    V-Drive Transmissions
    I went back and reread your original post....it looks like you have already replaced the coil and distributor cap....so that's a good start....

    cliff
     
  14. JVM225

    JVM225 Well-Known Member

    Apr 8, 2008
    Farmingdale, NY
    2002 410 Sundancer, Monaco Edition.
    3126 Cats.
    Could be the pick up in the distributor (cheap part) or the ignition control module (not so cheap). When they swapped the other motor in 2014 did they use the old ignition module (mounted on the riser/elbow)? If so, swap them form one motor to the other to see if the problem moves over,
     
  15. Stroh

    Stroh New Member

    26
    Apr 12, 2015
    SW Florida
    2006 Sundancer 240 "Toy Boat"
    5.0 MPI 260hp Bravo III
    The way we used to check for spark at the plugs: pull a plug out and attach the plug wire back to it, then ground the body (the threaded part) of the spark plug to the engine. Crank the engine over and there should be a blue spark arching between the electrodes on the spark plug. we were careful doing that, using insulated pliers or something insulated between us and the spark plug. Voltage into the ignition coil is 12 volts but the coil kicks the voltage up to 40,000 or so volts going to the spark plug.

    A simple 12 volt test light is cheap and can test for 12 volts at the ignition coil. Just attach the clip to a good ground, touch the probe to the + positive terminal on the ignition coil, have someone turn the key on (don't need to crank the engine over) and the light should light if you have power to the coil.

    For informational purposes only use at your own risk.
     
  16. CJM

    CJM Member

    71
    Aug 26, 2010
    CT
    1986 250 Sundancer /
    2000 340 Sundancer
    5.7 Merc /
    Twin 7.4 Horizons
    It could also be the shift interrupt switch, it cuts the voltage to the ignition for a second (while shifting).. Like stated before, you have to test all components, (backwards) for voltage. Start at 1 spark plug wire, then the wire from coil to dist, etc.. If you are not familiar with the steps, you should get a manual for your engine. It will have the basic troubleshooting steps. Good Luck
     

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