Out for the maiden voyage and did pretty well, a few carb/ignition questions

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  #1  
Old 06-11-11, 02:17 PM
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Join Date: Dec 2002
Location: Pittsburgh, PA
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Out for the maiden voyage and did pretty well, a few carb/ignition questions

For those of you who have not been helping me with this already... '78 Sylvan Sea Master with a '77 Merc 500 50hp 4 cylinder, just launched after 13 years and the boat was recently rebuilt.

I had a little bit of a rough idle in the driveway, but when I launched it, it cleared up after about 3 minutes. The idle is now smooth as can be, and it sounds great.

Issues....

* it seems to have a miss every now and then eventhough I have all new plugs, wires, rebuilt carbs, rebuilt fuel pumps... I have already ohmed the coils and they are all identical.
* if I nail the throttle I get a slight momentary bog
* it was tough to get it on plane with two 200+ people inside, maybe due to not being full throttle. Once it planes out the rpms come up a little and the speed comes up.
* I don't think that I'm hitting my 5200 RPMs, it seems as though my throttle cable may need to be adjusted. There seems to be a deadband in the middle of the throttle, it rpms come up right off of idle, the middle really doesn't do much, and I have to go a little more than 90 degrees to be full throttle which may not even be full throttle.
* I also have bubbles in my fuel line.. may be normal???
* this lower unit is not the original and the prop is now a 13 pitch, but I still have the 12 pitch.

I ran about 1/2 tank of fuel thru it today, minor issues but finally on my way!
 
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Old 06-11-11, 06:05 PM
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UPDATE, I pulled my new centerfire plugs and I can see that cylinder #2 is not firing, it looks like it just came out of the box. Plugs 1-3-4 have a flamefront mark as expected. I ohmed the coils again and I find that #2 is open on the secondary to ground, unlike the other 3 that are 1100 ohms or so. I removed the coil and it has a hole burnt right thru the coil to the aluminum cover. Oddly, this is the only coil that is not original to the motor and it has a funky connector on the plug wire that is not original. When I made new plug wires, I noticed that it was different. I'm wondering if that wrong connector caused the problem. Some electrical coils can eat themselves up if powered and the secondary side is left open???



I found a new replacement coil so I ordered it and the plastic fuel inlets that I want to replace.



Well.... landsided again!
 
  #3  
Old 06-12-11, 03:37 AM
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Join Date: Apr 2007
Location: Near Buffalo, NY
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I'm glad you've got it figured out. As you probably know by now, I'm not an outboard guy. Samauri has far more knowledge than I when it comes to OBs, but he seems to be scarce lately. It is his busy season though ...
 
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