'73 chrysler 85hp bogging and misfiring

[ktmracer]

I have a '76, 19' invader with a '73, 85hp Chrysler. The motor starts and idles fine. When I try to go to full throttle it bogs for a good while(3-5 min.) then will eventually start picking up and plane out. When it gets planed out it still surges. It has a new fuel tank, new fuel lines, and clean carburetors. I'm experiencing excess fuel consumption, about 6 gal. in 2 miles. It has the magnapower ignition which I don't know a thing about. The plugs are new. All help would be greatly appreciated!!!

 

[12Footer]

Re: '73 chrysler 85hp bogging and misfiring

Welcome to iboats. WoW, that's alota fuel!!!<br />Have you checked the choke plate in the carb,to make sure it's not sticking closed? Not much else could cause this,without throwing fuel back into the cowling.A carb may have a sunken float, or sticking needle valve,but they don't normally 'correct themselves' like you described.<br />Another thing that is rarer than windows without glitches, is the metering jet falling-out into the carb bowl. Usually, you're lucky to get them out without butchering the pickup in the carb.But it should be checked,nonetheless.<br />Hope this helps, as other than that, I'm clueless.

 

[ktmracer]

Re: '73 chrysler 85hp bogging and misfiring

Thanks for the info. 12Footer. The choke plates are operating correctly, i'm not sure about the floats and the needle valves yet. Is it possible that my problem lies in the firing? The bottom spark plug has a darker porcelain than the other two and they have all been ran about 3 hrs. at most. It acts like its only running on 2 cylinders then the other one will slowly pick up.

 

[aeronutt29]

Re: '73 chrysler 85hp bogging and misfiring

This trick may require some special trickery, but see if you can operate each choke individually while the motor is running under power. If activating one of the chokes (presumably the bottom one) produces very little or no change, you've found the weakest link. A compression test isn't a bad idea either. I just got done doing a compression test on my motor (6 cyl Merc) and found that the bottom cylinder is significanly below the others in compression. This confirmed my previous suspicion that it's not doing it's share of the work. Hopefully you don't have a low compression problem, but the "choke one at a time" trick did point me in the right direction on which cylinder to look at more closely. Also, if you haven't already done so, go buy a can of Deep Creep at your favorite boat dealer and use it liberally. It made a HUGE difference in how my motor runs. (now if only that bottom cylinder would fix it's self).

 

[racohoon]

Re: '73 chrysler 85hp bogging and misfiring

Aeronutt--<br /> What is this deep creep stuff? Ihaven't ever seen/heard of it @ any of the marinas around here.