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fallingfowl

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"I own a 1978 23" glasply

"I own a 1978 23" glasply cuddy with a mercruiser 233 (Ford 351), 2-barrel Rochester Carb and Alpha 1 drive. It has Pertronics "Ignitor" aftermarket Electronic ignition. All fuel is new 87 octane fuel, after having run out the 2-year old fuel that was in the tanks when I bought it last year.

I have replaced the electric in-line fuel pump, checked all fuel lines for obstructions, rebuilt the carb, during which I found the power piston (not the accelerator pump) in the carb was not moving (corrosion?). I cleaned it up and got it moving well. After the rebuild, the symptoms below went away and My son and I had a fine one hour trip on the freshwater lake near here, starting stopping, run WOT, etc.

Now the problems are back.

Here are the symptoms I have:

Runs fine in the driveway, at the dock, under no load. WOT is 4300rpm in neutral under these conditions.
Runs ok when under load, but WOT is only 3000RPM. After it warms up, it begins to run rough, missing, surging, and generally acting sluggish and spotty. It will die at idle. Once it sits a bit, I can restart it and we repeat the problems as it warms up. By the way, this has all been happening in the saltwater (probably not a contributing factor, but it is a variable I have considered)

I have narrowed things down to :

1: Still got a fuel supply problem.
2: The ignition system is whack.
3: The boat is a trailer queen.

Thanks in advance for your help."
 
Are you telling me that you ha

Are you telling me that you have a high speed misfire while underway? If so could be a defective coil.
 
"You may need to completely dr

"You may need to completely drain and empty your fuel tank and clean out all the old junk, then change all your fuel filters, so as to get pure gas going to your carb. Don't forget to check/clean your anti-syphon valve, and your carb inlet sintered filter, if equipped.
Rod"
 
"Yes, a high speed misfire whi

"Yes, a high speed misfire while underway sounds right. could a faulty coil also cause the low WOT RPM? What;s the best way to check it? Just put in a new coil?

Thanks for the advice Rod. The 4300 RPM with no load was just up and back down to see if it would get there. I will not ever, ever do it again on purpose.

I will check the fuel and the filters again but I did just change them. Then again, I refilled the tanks for the first time after changing the filters, so, that is still worth checking.

I will also check to see if i have anti-siphon valves. I do have three separate lines from the three separate tanks coming in to a common line to the carb. Each of the tank lines has it's own shutoff petcock."
 
Coils when they are bad tend t

Coils when they are bad tend to act up as the engine warms up.
 
"If the coil is over 5 years o

"If the coil is over 5 years old or of unknown age, especially with the symtoms you gave me, I'd get a new coil for good measure. Then see what happens."
 
"Yep. I went and bought a new

"Yep. I went and bought a new coil because it is both over five years old and of unknown age. Going to replace the plug wires, too, for good measure."
 
"When it comes to plug wires I

"When it comes to plug wires I like to go all out. Especially on a boat engine. Get a high performance street legal set (MSD, Accel, Taylor ect) from a speed shop or auto parts that carries high performance ignition parts. Be real careful transfering the new wires. Do it very deliberately, transfering them one at a time so as not to mix them up."
 
"Thanks Eddie. I did buy MSD p

"Thanks Eddie. I did buy MSD plug wires and an MSD coil. I had to install a .8 ohm resistor with it.
I agree with your method for replacing plug wires. I made the "yank them all out first" mistake a long, long time ago. It's a mistake akin to leaving the transom plug out of the boat. If you are smart, you only do it once.

So, tomorrow, I will report the results of the replacement coil and wires."
 
"Chris:

Don't forget

"Chris:

Don't forget the di-electric grease. Using a
Q-tip, I like to swab the inside of the plug boot end of the wire and connector. Sure makes it easy to get them off for the next plug change. For the dist. cap wire end, dab a little only on the metallic cap towers and not the boot. They are short and tend to pop loose.

Also clean the inside of the boots on the dist. and coil ends of the wires and the outside of the coil and dist. towers with some alchohol to prevent caps from slipping off while under way; they are silicone and slick.

I did the wire mistake once and had a time of it figuring it out. Then 20 years ago, my non-mechanical aptitude son was helping me on his Jeep when I said we'll change them one wire at a time. I went to get a cool one and heard "dad, I got the wires off". My neighbor helped us out. LOL Guy"
 
"OK, things are a lot better n

"OK, things are a lot better now. Start well, runs well. I did have a scare when it started acting up again, but fixed that by setting the timing correctly. Now, it did have a couple instances where the engine lost all power momentarily, then came right back. And, I still can't get more than 3200 RPM at WOT. I attribute the momentary glitch to bad fuel (hope, hope, hope), but I still don't get the "low" RPM's. I was making way at about 40MPH, by my GPS's reckoning. Maybe the prop isn't right sized?

Thanks for all your help guys. I am a new boat owner and this place is great for me!"
 
"Rod;

I was thinking the sa

"Rod;

I was thinking the same thing about the Tach. I haven't checked it yet, but will. A friend asked why I even care that I am not at full RPM at the speed I am making. I thought that was a good question.
Why should I care?"
 
"Maybe it's just me, but I

"Maybe it's just me, but I would have to have it working properly. It would nag at me to know it was not right, and God knows I don't need MORE nagging!
Rod"
 
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