Motor crapping out ???

[JT2Fast4U]

Hi all... I took my boat out for the 1st. time this year, about 3 weeks ago, & it ran great. No problems at all. Then I took it out the following week & it ran fine most of the day, up until I was about to leave, & then it started crapping out & missing real bad, & wanting to die. I barely made it back to the launch ramps. After I got it back home, I did a tune-up on it (plugs, dist.cap, rotor & new air filter). I also drained the gas tanks, (thinking there might have been some water in there), & filled it with fresh fuel. I also found a couple of the rubber vacuum caps, on the carb. were cracked or split, so i replaced them also. I took it out again this past weekend, hoping that I solved the problem, & it ran pretty good for about 15 minutes, then it started doing the same thing again, missing, stumbling, & wanting to die out on me. So I shut it off for about 30 minutes or so, & fired it back up again, & it ran good, but for only a few minutes, then started the same shit again. The motor isn't overheating (temp. is normal, 120-160), oil pressure is fine, & fuel pressure is fine too. It always starts right up & usually idles fine too, except for when this problem started happening (then it doesn't want to idle very well).
From reading other posts in here, I'm thinking the problem may be in my ignition system, particularly my coil, but I'm not sure. That's why I'm posting this. I'm hoping you guys can give me some ideas, or things to check out, or test... My setup is basicly a stock 455 olds, with a Torker intake & a Mallory Electronic dist. & Mallory coil, Q-jet carb., & exhaust logs. With a Jacuzzi jet. If you need anymore info, I'll be happy to post whatever ya want to know. Well, thanks for any help you guys can give me on this, I appreciate it very much... Thanks again, JT2Fast4u...

[Sleek468]

I had the same problem in the beginning of thid year and it tured out to be the wires that go to the ballast resitor were a little loose. I put some new connections on there and everthing was fine. I would also check your float level, it may be a little high. I would also check for correct plug gap. And also check the needle and seat to make sure there is no crap in there keeping it open, if you used any teflon tape on your fuel line connections sometimes pieces get lodged in the carb. GOOD LUCK!!

[Nucking futs]

sounds to me that the coil may be going or already is. Also check you ground wire on the tach..

[Mr. Crusader 83]

check the ground and power wire on your ignition also try rebuilding your carb.... i had those same problems last weekend and it was loose power wire on my msd ignition. did you have a fuel sep. i would also change that or install one if you dont have one. it will save you a big head ache. good luck man.
http://www2.***boat.com/image_center...ar_003-med.jpg
:idea:

[TAYLORCHET]

I had a simular problem and my turned out to be vapor lock as it was really hot out and even though I had an elecktric pump it was vapor locking just a thought!

[SmokinLowriderSS]

Ignition coil failure under heat load. I had it happen summer 2003.

[Captain no fun]

You don't say what kind of ignition you are running. If it's points, the condenser is your most likely candidate. I'm on board with a heat affected component of some sort related to your ignition. Heat is resistance, and a bulid up of heat somewhere is your likely cause. Feel you wires feeding your system directly after a failure, if it's warm, or hot you're on track. Also check for a kinked wire somewhere, a sharply bent/trapped wire will buid heat, and cause you grief. Good luck, it can't be hard, just stay motivated.

[Captain no fun]

You don't say what kind of ignition you are running. If it's points, the condenser is your most likely candidate. I'm on board with a heat affected component of some sort related to your ignition. Heat is resistance, and a bulid up of heat somewhere is your likely cause. Feel you wires feeding your system directly after a failure, if it's warm, or hot you're on track. Also check for a kinked wire somewhere, a sharply bent/trapped wire will buid heat, and cause you grief. Good luck, it can't be hard, just stay motivated. ^The mallory unit may have an optical or magnetic pick-up. I'd thinks it's wiring leading, or a ballast resistor opening after heating up.