1978 chrysler 115

[robert4r]

I bought this boat about a year ago. Its a 1978 chrysler 115 with magnapower ignition. I cleaned carbs and replaced all gaskets replaced spark plugs compression is 140 on all cylinders new gas tank and fuel lines did a link and sync per sticky on this site. Also did timing and its at 32 degrees wide open throttle. Finally after all this and a few months I got the boat to run on the water . The problem is that it will open up for a second then boggs downn like its dumping fuel the top two spark plugs (cjampion l20v) after running turn black from burning fuel however bottom two cylinder 3 and 4 look brand new and smell like gas. The bout uses insane amounts of gas just to barley cruz across the lake the gas smell is strong while driving the boat almost like its just dumping it in the water I need help im lost I have looked in the manual and I just dont know what it could be any assistance would be greatly appreciated thank you

 

[Frank Acampora]

Double check the fuel pump diaphragm. A cracked diaphragm or even one with a pinhole will cause gas to enter the bottom two cylinders causing misfiring. Since the engine is effectively running on two cylinders and since raw fuel is entering the bottom cylinders, fuel mileage will go down drastically.

Re-check your work on the bottom carb: A float stuck in the down position or a worn inlet needle and seat will never shut the fuel and again, raw gas will be pumped to the bottom two cylinders.

You would expect to use about 12 gallons of fuel per hour at wide open throttle.