1987 Ski Supreme ignition Coil Wiring

Discussion in 'Gas Engines' started by whbjr24, Jun 23, 2015.

  1. whbjr24
    Joined: Jun 2015
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    Location: Enfield Ct

    whbjr24 Junior Member

    I have been having problems starting my 351 ford engine. It seems that the starting spark from the coil is week. After much troubleshooting, I have noticed that the purple wire from the starter relay (provides 12 volts on cranking) had been removed. See the attached diagram.
    So my questions are:
    Q1) Why would someone disconnect this wire? I can't think what would cause you to do this. Worried that there may be a good reason I just can;t think of.
    Q2) Can I reconnect the purple wire from the relay (verified it supplies 12 V only when cranking) to junction point B without damaging the voltage regulator?

    Q3) On a side note, how does this junction point (B on the diagram) operate the choke on the carb? Is it just a heater or does it modulate it in some way? How do I know if it is working?

    Thanks in advance, Bill
     

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  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The bypass wire from the starter goes directly to the ignition coil's terminal. Because the voltage drops while cranking, the coil doesn't need the inline resistor. Make sure the coil you have is not of the type with internal resistance. If it is, the inline resistor will drop the voltage too much and the spark will be weak.
     
  3. whbjr24
    Joined: Jun 2015
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    whbjr24 Junior Member

    Gonzo, Thanks for the response!
    That is what I was thinking and it seemed to make sense but being new to boats, I wanted a dose of experience and collective knowledge base before I made a change.
    The coil I purchased specifically states on it's side that it needs an external resistor and in fact the boat has a resistive wire, coiled on itself, to create the original ballast resistance of 3.2 ohms. I had to tap off the center of the wire to get the recommended 1.8 ohms for the coil I purchased and installed. The far end of the wire is just capped with electrical tape for now.
    I'm still puzzled as to why the original owner removed that cranking wire. Can't think of any rationale at the moment.
    Thanks again, Bill
     
  4. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    You're welcome and good luck with your project.
     
  5. whbjr24
    Joined: Jun 2015
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    whbjr24 Junior Member

    Quick update: added wire from starter relay to the coil +. Starts great and quickly. Good primary coil voltages.

    Now the next problem - runs OK at throttle but will not idle. Hmmm. Just had the carb rebuilt two weeks ago.
     
  6. Ike
    Joined: Apr 2006
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    Ike Senior Member

    You may have had the carb rebuilt but did the rebuilder actually run it on the engine and correctly set fast and slow idle? I had a carb rebuilt two years ago and had a similar problem. I had to readjust the idle screws. Now it runs fine.
     
  7. whbjr24
    Joined: Jun 2015
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    whbjr24 Junior Member

    Thanks Ike.
    When I first got the boat back from the marina after being "tuned up" for the summer, I ran it briefly on a local lake as a "test". It seemed a bit hard to start. (Fortunately I had fully charged the battey first expecting something like this from an old boat I just bought from a person that had it sitting in a barn for the last 7 years - kids had grown up). It finally started and seemed to run well at high and slow speeds. It did stall once as I brought it back to idle. I declared the test a success.
    Trailered it to NH a week later and immediately launched it - that's when the problems began - it would not start at all. Kinda embarrassing sitting there in the water at the boat launch with people stacked up waiting their turn. So a friend helped tow it to our dock. Diagnosis - very weak spark that led to the whole fiasco in the original thread that I have since fixed. The motor now reliably starts with the throttle open but won't idle. It's weird.
    More troubleshooting today - it appears the fuel filter was not replaced and it had some debris in it so I cleaned it. Still starts right up with the throttle open but won't run at idle.
    I see 3 possibilities:
    1) Floods - but seems to start back up pretty easily with throttle open.
    2) Starves - but I can see fuel dripping into the barrels as I bring it to idle - but I have the old filter still on my mind. (The main choke is open but I never see the other flapper open though)
    3) Loss of spark - Find this one hard to believe as I have a good voltage at the coil positive terminal.
    Tomorrow I'll try to play with the idle screw and see but my gut tells me it something more. First on the agenda though - replace the fuel filter.
    Any other suggestions? Its a holly carb stock on the 87 Ski Supreme. I must admit I am learning a lot but would rather spend my time zooming across the water as opposed to hunched over the engine...
    Thanks, Bill
     
  8. Ike
    Joined: Apr 2006
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    Ike Senior Member

    odd. I am not familiarr with a holley but generally speaking they all work the same. The choke is closed when they are started and opens as the engine warms up. The choke operates a fast idle cam that keeps the engine running at a fast idle but as the choke opens the cam is released and the rpms slow down. what kind of choke? Manual, auto? vacuum or thermostatic? Sounds like the choke is not opening or not releasing the fast idle cam. Is the choke opening as the engine warms up?
     
  9. whbjr24
    Joined: Jun 2015
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    Location: Enfield Ct

    whbjr24 Junior Member

    Ike, Its an automatic choke and seems to be working.
    I am replacing the fuel filter cartridge today since it does not look like its ever been changed.
    However, I see that there is another device inline in the fuel line. I am not sure what it is. Another filter? Why would there be 2 in series. Anti-syphon device? Some sort of back flow prevention? The old parts list for the engine I found on line does not have this device listed anywhere.
    I attached two pictures, one is the fuel filter cartridge case on the bottom of the fuel pump for reference and the other is this unknown device in the fuel line.

    Any idea what it is? There is a bracket that holds it in place in the bilge so I am assuming its part of the original design.
    Thanks
    Bill
     

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  10. Ike
    Joined: Apr 2006
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    Ike Senior Member

    Never assume. LOL

    My engine (a Mercruiser 165- the old GM 250) has two fuel filters. The first is at the fuel pump like yours and another small one built into the carb. However, what I see in the pic looks suspiciously like an in-line auto fuel filter. Beware of those. They are often not made for marine use and don't meet the fire resistance standards. Also, why in the bilge? Beats me. Maybe someone else here has an idea? I would just take it out completely and replace the hose, and get it out of the bilge. The bilge? perfect place to dump a fuel leak!

    I have seen several boat fires from leaky auto-style in-line filters. I do not think it is part of the original design. The basic principle in boat fuel systems is to eliminate as many fittings as possible because fittings is where the leaks are and make pressurized fuel lines as short as possible. That's why the pump is required to be on or within 12 inches of the engine. Unless you can find something that tells you that filter is supposed to be there I would get rid of it.

    It does not look at all like an anti-siphon valve. You only need one if the tank is higher than the fuel inlet on the engine (the inlet at the fuel pump), that is, the fuel flow from the tank is downhill. If it's up hill an anti-siphon valve is not required.

    Is this by chance a PCM engine? (Pleasure Craft Marine) They used a lot of Fords and they put them in a lot of ski boats. If it is contact PCM and see if they can help. http://www.pcmengines.com/ I used to know the guy who ran PCM but that was years ago. Anyway, they made very good engines.
     
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