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mercruiser 470's help please.....

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bcain724

Member
Hello all I have twin mercruiser 470's 165hp my problem is both engines within weeks of each other started to run badly It seems like the carb is loading up or something....I can't throttle up form 1000rpm or even at 2000rpm it will load up if you will.....carb's were rebuilt 3 seasons ago....fuel fitlers are new, fuel pump is not bypassing fuel back into to carb(working fine) gas has been run through it few times this year (few tanks fulls I mean) new points, just can't figure it out please any help would be great right now.......
 
bcain724 said:
Hello all I have twin mercruiser 470's 165hp my problem is both engines within weeks of each other started to run badly It seems like the carb is loading up or something....I can't throttle up form 1000rpm or even at 2000rpm it will load up if you will.....carb's were rebuilt 3 seasons ago....fuel fitlers are new, fuel pump is not bypassing fuel back into to carb(working fine) gas has been run through it few times this year (few tanks fulls I mean) new points, just can't figure it out please any help would be great right now.......
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load up which is starving for fuel , hesitation.? ..could be fuel tank pickup plugged ..drain tank with the fuel line feeding the fuel pump see what the flow is like...check the fuel pressure to carb 3-6psi out of fuel pump ..

take the carb top off and see if the float bowl is contaminated etc...
 
checking the carb float was the next thing I was thinking ....but the only thing that gets me is both engines are doing it?!?!?!?! kinda weird seems like it maybe something in common or just **** luck...
 
bcain724 said:
checking the carb float was the next thing I was thinking ....but the only thing that gets me is both engines are doing it?!?!?!?! kinda weird seems like it maybe something in common or just **** luck...
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you have two fuel tanks ? one for each motor ? or all fuel is common to both engines all the time ?
 
single tank....I didn't look so not sure if they share a single pick up from the tank....but i think they each have there own pick up since i have 2 lines going through the bulk head from the engine conpartment to the tank
 
bcain724 said:
single tank....I didn't look so not sure if they share a single pick up from the tank....but i think they each have there own pick up since i have 2 lines going through the bulk head from the engine conpartment to the tank
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since these engines use the same tank looks like a fuel problem ..bad fuel over time will cause your problem..

do you treat the fuel with stabilizer ? using these products with the current fuel that has alcohol prevents or lessens fuel damaging the system.
 
yeah it does sound like a fuel problem but its not old gas in there....I've been through 2 tank fulls this season.....and it a 200gal tank......if I put some stablizer in now would it help....couldn't hurt right? another thing is my fuel/water filter was old I have changed them now....could water have gotten stuck in my carb. ?
 
I pulled the fuel filters off the carbs today washed em with carb cleaner and sprayed cleaner in the fuel suppy area.....put stablizer in the tank and ran the boat no problems (crossing fingers) I think it was just the old filter/water seperators that was thew prob and I had to get the carbs cleaned a little bit from that
thanks for the help
 
bcain724 said:
I pulled the fuel filters off the carbs today washed em with carb cleaner and sprayed cleaner in the fuel suppy area.....put stablizer in the tank and ran the boat no problems (crossing fingers) I think it was just the old filter/water seperators that was thew prob and I had to get the carbs cleaned a little bit from that
thanks for the help
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always use stabilier with fuel...always carry a spare fuel filter..

not fun stuck out on the water because of a lack of fuel conditioning...not to mention damage to engine with running tooo lean..
 
A water fuel seperator filter will only filter so much water then it reaches it's saturation point it will let water into the carb. If both engines are running bad then it is definitely a fuel problem with your tank. Could've gotten a tank full of bad gas. Wouldn't be the first or the last time that's happened especially from a marina fuel dock. Replace your fuel/water filter and pull the line from the tank and stick in a portable tank full of fresh fuel and see if it clears up.
 
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