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2000 mercruiser 3.0 hard start and idling isues

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dschoening

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I have a 2000 Sea ray 180 with a Mercruiser 3.0L motor. I just changed the fuel pump to a Carter model number m60337. fuel pressure is reading 4.5-5.5 psi when i try to start it. on the water the boat runs good above 1000 rpm, no hesitation Just gets up and goes and sounds good . but under 1000 rpms idles like crap. I tried to set the idle mixture and idle screws under a load in the water but once going below 1000 rpm the motor does want to run very well. a couple times the motor died and in order to start it i have to go full throttle as if it's flooded. most of the times even if i used the key to shutdown motor I have the same issue, I have to go to full throttle to restsart. the funny thing is when I brought it home and put it on the ears to flush the motor it was starting right up in idle. still rough idle but would start. after what I have read. think I need to rebuild carb. or get a new one.*

just wanted some input before I go down that road in case it might be another issue I am missing. thanks in advance for the help
 
dschoening said:
I have a 2000 Sea ray 180 with a Mercruiser 3.0L motor. I just changed the fuel pump to a Carter model number m60337. fuel pressure is reading 4.5-5.5 psi when i try to start it. on the water the boat runs good above 1000 rpm, no hesitation Just gets up and goes and sounds good . but under 1000 rpms idles like crap. I tried to set the idle mixture and idle screws under a load in the water but once going below 1000 rpm the motor does want to run very well. a couple times the motor died and in order to start it i have to go full throttle as if it's flooded. most of the times even if i used the key to shutdown motor I have the same issue, I have to go to full throttle to restsart. the funny thing is when I brought it home and put it on the ears to flush the motor it was starting right up in idle. still rough idle but would start. after what I have read. think I need to rebuild carb. or get a new one.*

just wanted some input before I go down that road in case it might be another issue I am missing. thanks in advance for the help
Click to expand...

You were right. It IS flooding. It is getting too much fuel into intake at carb. Either the lbs. of cuel preasure is to high or your needle & seat are whacked and/or the bowl needs adjustment. Btw. have you checed the throttle cable adjustment at the linkage and idle speed set screw?
I'm sorry, I dont know if you are carborated or efi...if efi, disregard.
Sorry...
 
after what I have read. think I need to rebuild carb.
Click to expand...

Ayuh,.... That's exactly where I would start, 'n throw in a compression test to get a baseline of the motors overall general health,.....
 
Check for vacuum leak at idle. having to open up the idle mixture could mean that it is very lean at idle due to the air leak. If there are none, then you may want to check the idle jets for dirt/corrosion, etc., which means opening it up.
 
2000 is a pre ethanol engine... When is the last time the carb was disassembled and cleaned??? Some carbs have internal parts that degrade in ethanol. Among these parts is the tip on some carb float valves.
About once every 4 seasons since ethanol, I have to disassemble my carb and clean it. The crap that ethanol can deposit in jets is often a hard sand colored plaster-like substance that is NOT soluble in carb cleaner and has to be mechanically removed..

If you still have the circa 2000 OEM fuel lines they MUST be replaced. This includes: line carb to fuel filter, line fuel filter to shut off, line shutoff to tank, the fill and vent lines. If you don't do this you will have an endless supply of crap deposited in your carb as the linings of pre ethanol lines is solvent in ethanol. If the float on your fuel sender is plastic, replace it as well.
 
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