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Crusader 1989 carb 270hp rough idle

M

makomike1

Contributing Member
Boat ran fine all day, came to marina pulled throttles back and strb motor dies. I started up give it gas and in marina I go. Go out next day get 1/4 mile away on plane and strb motor dies. Try to start it, rough starting,need full throttle to start ran rough and died. Limped back to marine on 1 motor. I have tried a new module,a new coil,checked the timing that did not work, changed all fuel filters and had the carb rebuilt no help.. When engine cools it starts up and idles great,its only when the motor heats up that it idles rough and or dies. I have to keep the rpms at 1000 or higher to keep running. I have pertronics flame thrower electronic distributer. Guys I need help, any suggestions Thanks Mike
 
I'm leaning towards a fuel problem--sounds like classic flooding (and I see where you had the carb rebuilt). You also might be getting some crud in there from ethanol gas.

Jeff
 
makomike1 said:
Does not make sense, my other motor runs fine from the same pickup tube from the tank. What would you do.
Click to expand...



What does the pick up tube have to do with a fouled carb?

Swap the carbs on the engines.

Chances are your rebuilder used an after market kit and the needle valve is not seating properly 100% of the time hence the stalling.
 
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The motor idles fine when it is cold, starts right up and idles perfectly, its only when you take the boat out and get the engines hot, then when you pull throttles back the motor runs rough and dies. Its a hard start, must have it at full throttle and you have to keep it at 1100rpms for the motor not to stall whether in gear or out of gear. Chris thank you for your help and patients so far
Mike
 
Docksidemarineservices said:
What does the pick up tube have to do with a fouled carb?

Swap the carbs on the engines.

Chances are your rebuilder used an after market kit and the needle valve is not seating properly 100% of the time hence the stalling.
Click to expand...

What I am saying is, If the needle valve and seat are aftermarket, they will work intermittently. I have had the same problem with my own boat until I purchased the original needle and seat from GM. I would come off of plane and my port engine would stall. The carb would flood the engine. Had to hold it wide open just to get it started. Had the engine cover off and watched the fuel come right out of the bowl vent. Replaced the needle and seat with OEM parts and has not happened since.
 
Chris, I switched carbs and that did not fix the problem,has to be something else. I am letting my marina mechanis look at it. I will let you know what the fix is. Thanks Mike
 
Sure sounds like flooding. Easy enough to rule out. When its doing it, remove the flame arrestor and have a look. Are you saying that when you switched carbs side for side you still had the issue with the starboard motor? If so i guess not carb related.
 
I would swap module from side to side. I know you said its new but my friend had a module that would act up when hot.
 
Hey Mike I'm having the exact same issues with my engines, one works perfect and the other is acting just like yours is.
I also had carbs rebuilt last year.
Please keep us posted when you find a solution.

Good luck
Ken
 
My mechanic found the problem today. It had been infront of me the whole time. It turned out to be the distributer cap and rotor. I had put a brand new Pertronix flame thrower distributer in 1.5 years ago. I would not have thought the cap would be bad but it was. Moisture must have got inside and corroded all the contacts inside the cap. I looked at the old cap and the metal contacts inside was all green and dirty.So they changed the cap and the rotor, runs like a new motor. Thank god. Talk about frustrating.
Thanks Mike
 
Another case of a "marine" distributor in name only. Slapping that word on a car part doesn't make is marine capable.

Jeff
 
In reading this thread I had similar issues with Pertronix. In my case I used the conversion kit and the engines just didnt run right at all. Once I pulled them and put back my contact points (yes I said points) the engines responded as if they were new! My take is stick with OEM distributors, electronic or not. Most likely the original ones were Mallory? They make a distrib that will work in the marine environment - more reliable and built for what we do - boating!
 
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