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Discussion Starter · #1 ·
can someone explain how the standard merc seperator works? if it fills with water does it shut down the fuel supply?
 

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Not Right said:
can someone explain how the standard merc seperator works? if it fills with water does it shut down the fuel supply?
Yes, it does. But will warn you with poor engine performance first.
 

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Discussion Starter · #3 ·
changed the water sep and it fired right up, I cant believe that I got fuel that bad, I trailer so it's 100% gas station gas w/ 4 oz of startron every fillup. Filter was new this spring.

I guess I'll start carrying one, I dont really feel like running around with a little gas can to fill the filter up, Any ideas?
 

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Keep a filter wrench on board, If the engine starts conking out again, and your in a jam, take the filter off and pour the contents out and put it back on, the filter should fill back up again when the pump turns on.
and sometimes you will have to do it more than once.

The filter basically just allows the water to settle to the bottom of the canister and the pump draws the fuel from the top, when the filter has too much water, your engine sucks the water and will conk out..

You just may have been slowly accumulating the water in the fuel tank over time, and when the water level got high enough, your pick-up tube in the tank gulped some water thru the line and then into your filter...

Of course it does'nt hurt to keep a new filter on hand at all times..


PS, Get some of that "EZORB" in the SW store..
 

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i was told never just pour out and reuse filter because unfiltered gas can move to filtered side and mess up invectors
 

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TOMMY HIWAVE said:
i was told never pour out and put back on because unfiltered gas can move to filtered side and mess up invectors
correct and you need to fill the filter up with fuel or
it WILL not start...
 

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xsta-sea said:
correct and you need to fill the filter up with fuel or
it WILL not start...
You can hit the carbs with starter fluid or even WD-40 and crank it until filter fills in an emergency, it works, ask me how I know :dead1:
 

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chaos10meter said:
You can hit the carbs with starter fluid or even WD-40 and crank it until filter fills in an emergency, it works, ask me how I know :dead1:
thats not a good idea with starting fluid unless you want to install new rings.....
 

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chaos10meter said:
You can hit the carbs with starter fluid :dead1:



I really hate seeing damage from the misuse of starting fluid. That stuff should require a liscense so the idiot that kills an engine can be sued.


Carb cleaner spray, WD-40 or a gas mist can start a motor without damaging; diesel included. :winker:
 

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hey so im confused..... why would you need to fill the filter with gas prior to starting. Shouldnt the pump just fill it up???


I had what I think is a filter problem this weekend. We had been idling up river for probably 30 or so minutes. We decided to get on plane and head up river. Well all was good for a few seconds and then it just started sputtering and died. I cranked it over several times and it tried to start but ran really rough. I could somewhat keep it running by playing with the throttle.

Well I left it off for a few minutes while I checked out some things on the engine. Then I tried to start it again and it ran just fine.

The only thing I can think of is some bad gas / water in the fuel filter.
 

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Maybe, but when you get water in the fuel filter, it does'nt usually fix itself, but next time your idling for a long period, pull a spark plug or 2 and check it, it kinda sounds like your fouling the plugs, possibly just from a rich idle mixture.
 

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Fyhr Factor said:
Maybe, but when you get water in the fuel filter, it does'nt usually fix itself, but next time your idling for a long period, pull a spark plug or 2 and check it, it kinda sounds like your fouling the plugs, possibly just from a rich idle mixture.

I agree.......

It was the only time it has happened so I cant really put my finger on it. The only thing I could think of was water in the fuel / water filter. However I cant see how it would all of a sudden fix itself.....

who knows...
 

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Discussion Starter · #14 ·
Ok, this happened again last weekend. Ironically it was almost the same spot (18 miles across the bay) headed towards my destination this time.

This time whe it died I immediately shut if off, didnt try to start it again, replaced the filter (dry) and it fired right up. sputtered for a minute or two at idle then ran great the rest of the day including a 20-25 mile ride home.

i must have some sludge in my tank? seems to run for 2-3 hrs on a fuel filter than just dies. I am now keeping filters on the boat and I learned that I need two filters because when I change one I have none.

Thanks to Andy Duncan "Liquid Courage" for giving me a filter for security on the ride home.

Any thoughts?
 

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axkiker said:
hey so im confused..... why would you need to fill the filter with gas prior to starting. Shouldnt the pump just fill it up???
The pump draws fuel from the seperator.

Misconception that the seperator is on pressurized side.
The seperator does not shut off fuel flow if filled with water.


The outlet from seperator to filter is the center nipple. It only extends down into the filter by about 1 1/2" or so. Why ? Water is heavier than fuel and thus will be contained in the sperator by nature of it's weight. Once the level of the water reaches the nipple (outlet) it will pass any water that enters from that point on until you change the filter or empty water out of it.
 

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On the subject of why you have fill seperator with fuel before you can restart it is: electric pumps cavitate in the presence of air. Think props ! They don't pull to well but they push real well. Air collects across the vanes/blades/or what have you and it's game over.

Mechanical pumps have diagphrams that displace a volume and thus are very good at 'pulling' anything. Thus, you don't have to fill the seperators for them but will take a few extra cranking seconds to fill sperator before it can push fuel into the carb or FI system.


There you have it. Fuel system basics. I got more if you want it. :laugher:
 

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just for reference I replaced my fuel / water seperator this past weekend. I replaced it dry as a bone and it didnt have any issues starting right up. didnt take any extra cranks or anything. Fired up without issue.

I have a 454 mpi setup.
 

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Do you have the mechanical pump on sea water pump ?
These of course have a lot less tendency to run into this issue.

If you have just the electric pump, then you got semi-lucky. Reason why I say semi, is that installing it dry does not mean you'll run into that problem every time. It does mean that it is quite likely to happen though. That's all.

Oh, if line from seperator to pump has some fuel left in it, then that helps too. Pump primes easier and wallah. A totally empty line is what will help make it tougher for the pump to pull fuel.

Am I just rambling and not making sense ? Please tell me for my fingers hurt. :laugher:
 

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cfm said:
Do you have the mechanical pump on sea water pump ?
These of course have a lot less tendency to run into this issue.

If you have just the electric pump, then you got semi-lucky. Reason why I say semi, is that installing it dry does not mean you'll run into that problem every time. It does mean that it is quite likely to happen though. That's all.

Oh, if line from seperator to pump has some fuel left in it, then that helps too. Pump primes easier and wallah. A totally empty line is what will help make it tougher for the pump to pull fuel.

Am I just rambling and not making sense ? Please tell me for my fingers hurt. :laugher:

yes I have the mechanical pump on the sea water...... I think I have an electric as well which makes no sence to me, but ohh well
 

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Discussion Starter · #20 ·
thanks cfm, could the filter get so clogged with sludge that it shuts down? If I had water in the fuel enough to shut it down I dont think it would start right back up after I changed the filter.

I guess I can cut open the filter that is on there now, I think I threw away the bad one.
 
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