fuel/water seperator, fuel filter

[gleavens]

I have a 3.0L mercruiser, '86 vintage, there is no fuel filter setup on this rig, no in-line, nothing. I was thinking of mounting a spin on filter base back at the stern, can my mechanical fuel pump handle the extra pull from the tank thru the filter housing and back to the pump etc.?

 

[mkast]

Re: fuel/water seperator, fuel filter

A stock Mercruiser type spin-on fuel filter should be mounted between the mechanical fuel pump and the carburetor.

 

[IES99]

Re: fuel/water seperator, fuel filter

I have a 3.0L mercruiser, '86 vintage, there is no fuel filter setup on this rig, no in-line, nothing. I was thinking of mounting a spin on filter base back at the stern, can my mechanical fuel pump handle the extra pull from the tank thru the filter housing and back to the pump etc.?

I did installed one exactly like that on my '88 3.0L and found this: If the engine hasn't been started in a couple of weeks, it takes a long time for the pump to get fuel to the carb. It will eventually, but the starter has to run a long time.
S0....(I may take heat for this): I installed an outboard type pump bulb in the line between the filter and pump and prime the carb before starting it the first time. It hits right off. If I run it every week, this priming isn't needed.

 

[Rocky_Road]

Re: fuel/water seperator, fuel filter

I have a 3.0L mercruiser, '86 vintage, there is no fuel filter setup on this rig, no in-line, nothing. I was thinking of mounting a spin on filter base back at the stern, can my mechanical fuel pump handle the extra pull from the tank thru the filter housing and back to the pump etc.?

It will handle this very easily, and it needs to always go between the fuel tank and the fuel pump. Any of the popular kits (Sierra, Molen, Racor) will do just fine...but I prefer the ones that use the 3/8" diameter fittings instead of the 1/4" ones, for the increased flow. If the kit doesn't include the 10 micron filter element (necessary for ethanol gas), get one!

Happy boating!

 

[Fishermark]

Re: fuel/water seperator, fuel filter

A stock Mercruiser type spin-on fuel filter should be mounted between the mechanical fuel pump and the carburetor.

Actually it should be between the tank and the pump.

Be sure to use some A1 rated marine flexible rubber hose and the appropriate fittings and clamps.

Also make sure to get one designed for an I/O - not an outboard.

 

[mkast]

Re: fuel/water seperator, fuel filter

Actually it should be between the tank and the pump.

Actually it's mounted between the pump and the carburetor.

http://www.mercruiserparts.com/Show...1014&bnbr=120&bdesc=FUEL+PUMP+AND+FUEL+FILTER

 

[z1nonlyone]

Re: fuel/water seperator, fuel filter

10 Micron filter for ethanol? I have not heard this. I was under the impression that a 21 micron was acceptable?

 

[Fishermark]

Re: fuel/water seperator, fuel filter

mkast - my apologies. I stand corrected. :redface:

Any of the instructions I have ever seen have indicated the installation should be between the tank and the pump. Any of the installations I have done on my own boats have been between the tank and the pump and have worked well.

But.... I do see from the link you posted that it is shown between the pump and the carb.

 

[PiratePast40]

Re: fuel/water seperator, fuel filter

Conventional wisdom would be to place a filter on the suction side so that any leaks would not spray pressurized fuel. Guess it doesn't allways make sense.

 

[mkast]

Re: fuel/water seperator, fuel filter

Conventional wisdom would be to place a filter on the suction side so that any leaks would not spray pressurized fuel. Guess it doesn't allways make sense.

I posted information regarding the installation of a Mercruiser spin-on type fuel filter. If the installation is good enough for factory installation, I think it's good enough for USCG regulations.
Just a thought, isn't the spin-on engine oil filter pressurized?

 

[Rocky_Road]

Re: fuel/water seperator, fuel filter

mkast - my apologies. I stand corrected. :redface:

Any of the instructions I have ever seen have indicated the installation should be between the tank and the pump. Any of the installations I have done on my own boats have been between the tank and the pump and have worked well.

But.... I do see from the link you posted that it is shown between the pump and the carb.

You have apologized too soon...that parts list is for the 5.0 and 5.7 engine. There is no engine mounted aux fuel filter for the 3.0L.

Besides...if you follow the fuel line (part #17) in the diagram, you will see that it connects the pump to the carb. The filter in the parts diagram goes before the pump, and uses the fuel line (part #16) to send the fuel INTO the pump.

The 3.0L engine has to have an aftermarket fuel/water seperator added...and it has to be before the pump. There has been no factory exception....

Happy boating!

 

[Rocky_Road]

Re: fuel/water seperator, fuel filter

I posted information regarding the installation of a Mercruiser spin-on type fuel filter. If the installation is good enough for factory installation, I think it's good enough for USCG regulations.
Just a thought, isn't the spin-on engine oil filter pressurized?

Yes you did...but NOT for the 3.0L engine that the original poster had in mind.

And the filter that you linked shows that it belongs BEFORE the fuel pump...trace the fuel lines.

 

[Rocky_Road]

Re: fuel/water seperator, fuel filter

10 Micron filter for ethanol? I have not heard this. I was under the impression that a 21 micron was acceptable?

Not for ethanol laced gas...the 10 micron filter element was developed to correct this.

Here is a great article about these filters:

http://continuouswave.com/whaler/reference/fuelFilter.pdf

 

[mkast]

Re: fuel/water seperator, fuel filter

And the filter that you linked shows that it belongs BEFORE the fuel pump...trace the fuel lines.

Line number sixteen is attached to the fuel pump and the filter base assembly.
If line number seventeen is attached between the fuel pump and the carburetor, where does the fuel, pumped into the base assembly, go, into the bilge?
The information I posted is to illustrate a typical USCG approved installation.

 

[Eric 3.7LX Alpha 1]

Re: fuel/water seperator, fuel filter

Truthfully, it probably does not matter before or after the pump. Im sure the filter and housing can withstand the pressure. Mine is before, however... if between the pump and carb... unless I am mistaken, you can not have any hose clamps on the pressure side of the pump, to be USCG approved, so it would have to all be in inverted flare fittings and metal line. Unless I am wrong, someone correct me.

 

[Don S]

Re: fuel/water seperator, fuel filter

A stock Mercruiser type spin-on fuel filter should be mounted between the mechanical fuel pump and the carburetor.

Sorry, but that is incorrect. You NEVER want the fuel/water sep filter on the pressure side of the pump (suction side).
It should be installed before the fuel pump. This also keeps water and dirt out of the pump.

Mounting them on the transom has been done on many boats, and will not be a problem.

 

[mkast]

Re: fuel/water seperator, fuel filter

Sorry, but that is incorrect. You NEVER want the fuel/water sep filter on the pressure side of the pump (suction side).
It should be installed before the fuel pump. This also keeps water and dirt out of the pump.

Mounting them on the transom has been done on many boats, and will not be a problem.

Don, calm down.
The suction side of the fuel pump is connected to the fuel tank.
The pressure side is connected to the fuel filter base assembly (on every stock Mercruiser engine equipped with one, that I have ever worked on).
If you look at the link posted, line number eighteen (flexible) is on the suction side of the pump.
If line eighteen is connected to the tank, line sixteen (rigid) attaches from the pressure side of the pump to the base assembly. Line seventeen (rigid) attaches from the base assembly to the carburetor.

 

[Fishermark]

Re: fuel/water seperator, fuel filter

unless I am mistaken, you can not have any hose clamps on the pressure side of the pump, to be USCG approved, so it would have to all be in inverted flare fittings and metal line. Unless I am wrong, someone correct me.

That's what I had always heard too... but it is not true. You can use rubber line from the pump to the carb, but it has to be the appropriate rated line.

(a) Each hose used between the fuel pump and the carburetor must be USCG Type A1 hose.

Read more: http://cfr.vlex.com/vid/183-558-hoses-and-connections-19764324#ixzz0oIAbB1d8

If you do use hose, then the barb have to be a certain type. Here's the actual quote from the regs:

Except when used for a tank fill line, each spud, pipe, or hose fitting used with hose clamps must have: (a) A bead; (b) A flare; or (c) A series of annular grooves or serrations no less than 0.015 inches deep, except a continuous helical thread, knurl, or groove.

Read more: http://cfr.vlex.com/vid/183-530-spud-fitting-configuration-19764221#ixzz0oI87BQ5H

And since we are on the subject, the same regs outlaw any inline fuel filters -- those that are simply spliced into the line. They have to be permanently mounted either on the engine or the hull of the boat:

Each fuel filter and strainer must be supported on the engine or boat structure independent from its fuel line connections, unless the fuel filter or strainer is inside a fuel tank.

Read more: http://cfr.vlex.com/vid/183-570-filters-strainers-installation-19764375#ixzz0oI9SRr60

I couldn't find anything on mounting the separator before or after the pump. That doesn't mean it's not there... just that I couldn't find anything.

 

[ECVCHAMP]

Re: fuel/water seperator, fuel filter

Don, calm down.
The suction side of the fuel pump is connected to the fuel tank.
The pressure side is connected to the fuel filter base assembly (on every stock Mercruiser engine equipped with one, that I have ever worked on).
If you look at the link posted, line number eighteen (flexible) is on the suction side of the pump.
If line eighteen is connected to the tank, line sixteen (rigid) attaches from the pressure side of the pump to the base assembly. Line seventeen (rigid) attaches from the base assembly to the carburetor.

Take A closer look at that. #18 is on the top of the pump and is the failer line if the diaphram fails. #16 is from outlet side of filter base to suction side of pump. #17 is from pressure side of pump to carb.(thats why they list 5 different ones). hose from tank is not shown.

 

[bruceb58]

Re: fuel/water seperator, fuel filter

Actually it's mounted between the pump and the carburetor.

http://www.mercruiserparts.com/Show...1014&bnbr=120&bdesc=FUEL+PUMP+AND+FUEL+FILTER

Not sure what you are looking at but that filter is on the suction side of the fuel pump.

You never have a filter like that on the pressure side of the fuel pump. Line 16 is suction. Line 18 is rupture line. Line 17 is the only line that is pressurized and it does not attach to the base assembly as you said. It attaches to the pump.

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