Logo
Results 1 to 9 of 9
  1. #1

    Default 87 5.7 OMC - No Throttle Up / Electronic Ignition vs Points Question

    Hey guys. First post here. Let me say I am not a mechanic and only know enough to be dangerous!

    I have a 1987 Winner with a 5.7L OMC. We have owned it since it was new. In the recent years, we've seen a few issues that I need some help/ideas on.

    The boat doesn't want to throttle past about 3/4 throttle. It just bogs down and will eventually die unless I let up. If I am going fast enough, sometimes I can "work through it" to get to full throttle and the boat runs great, although I don't run it at full throttle for obvious reasons. The issue is when I'm pulling a skier, especially a slalom skier, I get get enough juice to get them out of the water without drowning them since I can't.

    I had one mechanic suggest I switch to electronic ignition instead of the points ignition, but I haven't tried that yet. The more I read, the more I am worried about just switching the points out with electronic conversion kit. I had him replace the points and nothing changed the issue. I've replaced the plugs, wires and fuel filter as well.

    Any ideas? I haven't really had a good diagnosis or anything that would point to the primary issue. I appreciate any feedback or input.

    Thanks-

    Rodge

  2. #2

    Default Re: 87 5.7 OMC - No Throttle Up / Electronic Ignition vs Points Question

    thoughts?

  3. #3
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    5,145

    Default Re: 87 5.7 OMC - No Throttle Up / Electronic Ignition vs Points Question

    Ayuh,..... Changin' the ignition won't help a fuel flow problem,....

    Yer symptoms scream a lack of Fuel,....
    Any Grease is Better,... Than No grease at All....

  4. #4
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    9,091

    Default Re: 87 5.7 OMC - No Throttle Up / Electronic Ignition vs Points Question

    .........................
    Quote Originally Posted by rodge_3210 View Post

    The boat doesn't want to throttle past about 3/4 throttle. It just bogs down and will eventually die unless I let up. If I am going fast enough, sometimes I can "work through it" to get to full throttle and the boat runs great,
    If you are able to get past this "bog", and see the engine run correctly, I doubt that you have a fuel related issue. Possibly a carburetor issue.... but let's take this further.

    although I don't run it at full throttle for obvious reasons.
    Yes..... Full Throttle or what we call WOT is for testing ONLY! It is not an RPM to be sustained!

    The issue is when I'm pulling a skier, especially a slalom skier, I get get enough juice to get them out of the water without drowning them since I can't.
    You may want to be using a different propeller for this activity.

    I had one mechanic suggest I switch to electronic ignition instead of the points ignition, but I haven't tried that yet. The more I read, the more I am worried about just switching the points out with electronic conversion kit. I had him replace the points and nothing changed the issue.
    Did he correctly adjust the dwell angle, or did he simply adjust the point gap?
    Was the "complete" ignition advance checked afterwards.... i.e., the Progressive and Total Advance?

    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  5. #5
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    5,145

    Default Re: 87 5.7 OMC - No Throttle Up / Electronic Ignition vs Points Question

    I doubt that you have a fuel related issue. Possibly a carburetor issue....
    Jeez Rick,.... the carb is a big part of the Fuel System in my world,.....
    Any Grease is Better,... Than No grease at All....

  6. #6
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    9,091

    Default Re: 87 5.7 OMC - No Throttle Up / Electronic Ignition vs Points Question

    Quote Originally Posted by bondo View Post
    Jeez Rick,.... the carb is a big part of the Fuel System in my world,.....
    Bill, you are correct! I should have worded it differently!


    .
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  7. #7

    Default Re: 87 5.7 OMC - No Throttle Up / Electronic Ignition vs Points Question

    It's a fairly new carb, so that could be the reason, but I don't think so. Last year, plugs, wires and fuel filter were all replaced. Filter didn't seem to have water or debris in it. I would only assume that the marine mechanic adjusted the points and dwell, but I haven't heard that term (dwell) mentioned until I started reading through some other threads here.

    In terms of the prop-this boat has pulled many, many slolam skiers over it's 30yr life, so I don't think that's the immediate need, although I know changing the pitch could provide for quicker starts.

    So, any other thoughts on what to look at? My local mechanic just told me that he wasn't going to work on boats older than 20yrs, so it looks like I'm out of luck with him. I do have other options in the area, but not near as convenient.

    I appreciate the help and discussion. Again, the boat runs fine for the majority of the time. It's just when I go from idle speed to fun throttle that I get the issue. This is the same for about any situation going to 3/4 throttle.

  8. #8
    Join Date
    Apr 2009
    Location
    Long Island, NY,
    Posts
    45

    Default Re: 87 5.7 OMC - No Throttle Up / Electronic Ignition vs Points Question

    You should pick up a dwell meter and an advance timing light.
    This will enable you to check dwell and timing yourself. The dwell angle is what determines the saturation of the coil and the strength of the spark. Dwell and point gap are inversely proportional; smaller gap = larger dwell angle and vice versa. The other important ignition checks are base timing (set at idle) and total timing advance (checked at approx 3,000-3200 rpm with the boat tied up in the water). These old style points distributors use centrifugal advance and they need a few drops of oil in the wick that is in the distributor shaft under the rotor. On the V8s the base timing is usually about 8*btdc and total timing advsnce is about 29 degrees. If the centrifugal advsnce weights are rusted and stuck you will not be getting the correct advance needed for normal performance.
    What carb do you have? If it's a 4bbl Quadrajet these are known to have a bog if not set up right. When set up right they perform very well.
    A little known part that can cause this problem is the anti siphon valve on the gas tank. If this sticks it will restrict fuel flow.

    if you want to switch to an electronic distributor is can be done but you will have to change the ESA module to one that will work with it. You need the ESA to work in order for the Cobra drive to shift into neutral. They can be found at CDI electronics.
    Last edited by louc; 09-19-2017 at 07:17 AM.

  9. #9
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    9,091

    Default Re: 87 5.7 OMC - No Throttle Up / Electronic Ignition vs Points Question

    .........................
    Quote Originally Posted by louc View Post
    You should pick up a dwell meter and an advance timing light.
    If the OP is still using the Kettering System...... yes. These must be set using dwell angle.

    As for the advancing style timing light...... I want to see my progressive and TA in Real Time and in Real Degrees.
    This is why I use the good ole standard strobe type timing light with the harmonic balancer marked off up to about 35 degrees.


    The dwell angle is what determines the saturation of the coil and the strength of the spark. Dwell and point gap are inversely proportional; smaller gap = larger dwell angle and vice versa.
    Point GAP is an estimate ONLY of correct dwell angle. Do it correctly, and set contact points using dwell angle!

    While the dwell meter is connected up, you will also be able to see if the dwell angle is constant during an RPM increase!
    If NOT...... you have other issues with the distributor shaft and/or bushings!


    The other important ignition checks are base timing (set at idle) and total timing advance (checked at approx 3,000-3200 rpm with the boat tied up in the water). These old style points distributors use centrifugal advance and they need a few drops of oil in the wick that is in the distributor shaft under the rotor. On the V8s the base timing is usually about 8*btdc and total timing advsnce is about 29 degrees. If the centrifugal advsnce weights are rusted and stuck you will not be getting the correct advance needed for normal performance.
    Worse yet...... would be rust compromised flyweight return springs!
    If the flyweights are not doing their job correctly....... the Marine Engine may suffer from Detonation Damage!

    Keep in mind that BASE is BASE.
    We fire up on BASE...... and we idle on BASE..... and that's it!
    Point being..... always look past BASE advance to the more important aspect of ignition advance.
    Look to see what the Progressive and the TA are doing.


    The SBC w/ the GM style F/D pistons should not see any more than 28* @ 3,200 RPM.


    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

Similar Threads

  1. Points to electronic ignition
    By jim davidson in forum Mercruiser Sterndrive Forum
    Replies: 6
    Last Post: 03-21-2017, 09:59 AM
  2. Ignition: electronic or stick with ol' points?
    By Myles_T in forum OMC Sterndrive and Inboard Forum
    Replies: 9
    Last Post: 04-20-2013, 09:58 AM
  3. 89 omc 2.3 wont run good after changed from points to electronic ignition
    By merkins1 in forum OMC Sterndrive and Inboard Forum
    Replies: 10
    Last Post: 07-09-2011, 03:24 PM
  4. Electronic ignition versus points style ignition
    By Curt Garrett in forum OMC Sterndrive and Inboard Archive
    Replies: 5
    Last Post: 10-14-2006, 05:43 PM
  5. Should I install a points to electronic ignition kit
    By Kevin Rawson in forum Archive 2003-2009
    Replies: 1
    Last Post: 05-17-2004, 01:01 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •