1971 120 hp engine troubles (Chrysler)

[mrjay180]

Hello all...Im very glad to have found this forum.<br /><br />I purchased a fiberglass runabout last year and had a great first summer with it. However, toward the end of the season I began to have minor problem where the motor dies if the rpm's fall under 12 or 1300. But if you up the idle too much, it makes the boat go into gear too hard. It also stalls a little when you have it in gear and go to accelerate. Any idea what could be causing this? Someone told me they think it might be the air/fuel mixture...but I know nothing about 2 stroke engines. Its a dual carb motor...where should I start?

 

[eurolarva]

Re: 1971 120 hp engine troubles (Chrysler)

Hello mr jay and welcome to iboats. First it would help to have a model number. Best place to start is to get a service manual. You can buy a factory manual online from www.chryslercrew.com If you go with an aftermarker manual I have the clymer and like it alot. Second place to start would be rebuilding the fuel pump. The kit cost is about 10 dollars from NAPA number 18-7806. If that dont improve the motor the next place would be to rebuild the carbs and replace all fuel hoses. The carbs should be done one at a time and dont mix parts from the different carbs. NAPA also sells carb kits for that motor part number 18-7037 and are about 15 bucks a kit and come with instructions. With the fuel pump kit just replace the diaphram and main gasket. You can also replace the glass bowl gasket and screen. The small gaskets are suppose to be for the fuel valves but they are the wrong size and do not fit. New valves are 5 bucks a piece and the correct gaskets are 50 cents each and are availible from mercury. I would not mess with them yet.<br /><br />When motor starts to kill try choking it and see if motor improves or just dies. If motor improves it is gas related. If it just dies I would next go to spark test and or compression test. If you have any questions along the way just post them.<br /><br />Good luck