Jump to content

Welcome to TheMalibuCrew!

As a guest, you are welcome to poke around and view the majority of the content that we have to offer, but in order to post, search, contact members, and get full use out of the website you will need to Register for an Account. It's free and it's easy, so don't hesitate to join the TheMalibuCrew Family today!

2005 Sunscape 21 lsv bogging down/ misfire under load


Recommended Posts

PaulFackrell

I have a 2005 Malibu Sunscape with a 5.7 Indmar motor.  The boat would run perfectly for about an hour, and then it would start to bog down and misfire under a load at first I thought it was starving for fuel so I replaced the fuel filter and then the fuel pump.  after that didn’t work I replaced the spark plugs, spark plug wires, cap, and rotor, and it still did the same thing.  I decided to turn my attention to timing, so I power timed the boat under a load by twisting the distributor back-and-forth until the motor ran at its strongest.  That didn’t fix the problem, but I was able to replicate the misfire that I had been experiencing by advancing or retarding the timing manually by twisting the distributor cap.  I replaced the ignition control module that is bolted inside of the distributor cap and finally the boat ran perfectly.  The next trip out it started to misfire again, and I realized that my RPM gauge or tachometer had not been working for quite some time. Apparently, if your tachometer is faulty, it can damage the ignition control module, which in my case is what happened so I simply unplugged the wire harness from the back of the tachometer and this permanently fixed my issue .  I went through an entire season trying to diagnose this issue so I thought that I would share it here so that hopefully I could help someone else..

Link to comment
9 hours ago, PaulFackrell said:

I have a 2005 Malibu Sunscape with a 5.7 Indmar motor.  The boat would run perfectly for about an hour, and then it would start to bog down and misfire under a load at first I thought it was starving for fuel so I replaced the fuel filter and then the fuel pump.  after that didn’t work I replaced the spark plugs, spark plug wires, cap, and rotor, and it still did the same thing.  I decided to turn my attention to timing, so I power timed the boat under a load by twisting the distributor back-and-forth until the motor ran at its strongest.  That didn’t fix the problem, but I was able to replicate the misfire that I had been experiencing by advancing or retarding the timing manually by twisting the distributor cap.  I replaced the ignition control module that is bolted inside of the distributor cap and finally the boat ran perfectly.  The next trip out it started to misfire again, and I realized that my RPM gauge or tachometer had not been working for quite some time. Apparently, if your tachometer is faulty, it can damage the ignition control module, which in my case is what happened so I simply unplugged the wire harness from the back of the tachometer and this permanently fixed my issue .  I went through an entire season trying to diagnose this issue so I thought that I would share it here so that hopefully I could help someone else..

Welcome to the crew.  What a great story of diagnosis.

I have not heard of a bad tach ruining an ICM, but I suppose it is possible to load the output too much.  It might be a good idea to download the MEFI manual for your version (MEFI-5, I think?) and set the base timing back to 10 degrees.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...