Idle problem with 96 5.7 2bbl

[fishingman220]

I have a 96 Merc 5.7 with a merc 2bbl., and alpha one. yesterday i went out on the river and it started fine 2times, ran perfect all day, then when i came back to the dock, comming through the no wake zone, got about 1/2 through and the motor died. it would only restart at 1/4- 1/2 throttle and would run fine, but as oon as you you back it down to put in gear it would shut off before i got it in gear. so it will not idle at all. i have over a half a tank of fuel, and i did stablize the fuel. any thoughts????

 

[CharlieB]

Re: Idle problem with 96 5.7 2bbl

Possibly got a couple of drops of water into the carb, clogging the idle jets.

Could be time to clean that carb.

On occasion I have gotten by for a while by briefly choking the engine manually at a moderately fast idle speed, (1500 - 1800), the sudden great increase in intake vacuum 'pulled' the water droplet thru the idle passage and the engine smoothed out and would then idle normally again.

Note that this also pulls a great amount of fuel thru the mains, and attempts to flood the engine, so by briefly I mean only a couple of heartbeats, NOT long enough to kill the engine.

If this does not improve idle quality then it is time to take the carb apart and clean it properly.

 

[fishingman220]

Re: Idle problem with 96 5.7 2bbl

well i would run it for about 5 or 10 seconds at 2000-2500rpms, and then bring it back down and still died, but i will put it on the muffs and try closing the choke, should i spray it down with carb cleaner???

 

[Bondo]

Re: Idle problem with 96 5.7 2bbl

should i spray it down with carb cleaner???

Ayuh,...

If it's a Clogged Up carb,...
You can't do any Good spraying around what you can see, with Carb Cleaner...
The Problem will be Much Deeper than that...

 

[John_S]

Re: Idle problem with 96 5.7 2bbl

If you are sure it is nothing to do with shift cut-off switch or cable, remove the flame arrestor and watch down the throat of the carb. If you see gas dribling and collecting on the butterflies, the float needle valve is probably sticking. Carb rebuild time.

 

[chiefalen]

Re: Idle problem with 96 5.7 2bbl

Take it apart and soak it in gas for a hour. Blow it dry with compressed air. Get a can of carb cleaner, get every single hole clean with the straw attached to the nozzle of the carb cleaner. The little holes are the ones that get ya. Spray the carb dry with air.

Then rebuild the carb with the rebuild kit you bought.

And then try it, careful with the idle needle when you screw it in gently and don't bend the tip.

Make sure you cleaned all the filters if you don't know where they are just ask.

 

[fishingman220]

Re: Idle problem with 96 5.7 2bbl

is there a manual on here for rebuilding the carb????

 

[Bondo]

Re: Idle problem with 96 5.7 2bbl

Ayuh,... It's covered in the engine manual found in the Adults Only section...

 

[fishingman220]

Re: Idle problem with 96 5.7 2bbl

ok so i got a new problem, the carb has been cleaned, but it didnt help at all. it almost seems like it is some sort of electrical prob. when it drops down below 2000 rpm, it shuts off like you turn the switch, it doesnt spit or sputter, it just dies like the cutoff switch was activated. and i dont know anything about the electrical, any ideas????

 

[Don S]

Re: Idle problem with 96 5.7 2bbl

What method did you use to clean your carb ?????

 

[fishingman220]

Re: Idle problem with 96 5.7 2bbl

took it off and took it tothe shop and had them do it. and it is doing the exact same thing, nothing changed

 

[Don S]

Re: Idle problem with 96 5.7 2bbl

Was there/is there water in your fuel system?
Have you dumped out the old fuel filter to see if there is water in it? If not try it, then install a NEW filter, do not reuse the old filter after dumping it.

 

[fishingman220]

Re: Idle problem with 96 5.7 2bbl

ok i will change that today, but i can start it, and it runs fine at 3000 then down to 2000 and then as soon as you go under that it shuts off, not sputtering at all, just shuts off fast, like turning the key or lanyard switch.

 

[Don S]

Re: Idle problem with 96 5.7 2bbl

Just make sure you dump the contents of the old filter into a clear containser so can see the seperation.
I can't see it being an ignition problem. If you was loosing spark below 2000 rpm, you would never get it started to begin with.
You might try running it with one of the spark plug wires off a spark plug and on a sprark tester and as the rpm comes down to where it stalls, see if there is still spark.
A compression test might also be in order. Noone here can hear or see it run so it may be something completely different.

 

[fishingman220]

Re: Idle problem with 96 5.7 2bbl

ok i replaced the fuel water seperator and cleaned the filter at the line in the carb, and got it running, i let it warm up but still wont idle below 1200 and only runs at 1/2 choke.

 

[Don S]

Re: Idle problem with 96 5.7 2bbl

Was there water in the gas?????????????

 

[fishingman220]

Re: Idle problem with 96 5.7 2bbl

not much

 

[Don S]

Re: Idle problem with 96 5.7 2bbl

not much

Let me find a bigger pry bar to see if I can't pry a little more info out of you.
How much is NOT MUCH.
1/4 water, 1/2 water

Have you tried backing the idle mixture screws out about half a turn?

 

[fishingman220]

Re: Idle problem with 96 5.7 2bbl

the seperator was about 1/4 water, no i havent done anything but took the vac line and blowed that out. i pulled the cap off and it was alittle carroded and the piece inside of it that the basket goes through had some corosion on it. should i try replacing any of that or just clean it and sand the points and put it back together????

 

[Don S]

Re: Idle problem with 96 5.7 2bbl

the seperator was about 1/4 water,

At that point, you will start getting water into the carb. Probably has already happened again.
You need to get the water out of the tank and the carb. Then replace the filter again.

The problem is, you never found the cause of your problem, just tried to fix the symptoms.

You may also need a tuneup, new cap and rotor. You don't have points, you have electronic ignition.