Adding an in-line fuel filter

[diskord]

So I just purchased a '68 Mercury 1000. The Outboard doesn't have a fuel filter on it, and none of the lines have a fuel filter on it, since the lines are starting to get a bit hard I figured I would replace them all. I have a few questions:

1) Can I just use regular 5/16's fuel line? The stuff I got at the autoshop is a bit thinner, black, and is designed for an internal engine compartment, but at the end of the day fuel line is fuel line... right?

2) I thought adding an in line fuel filter would be wise, so I picked up one at the auto shop. It is just a plastic cylinder with a cardboardy "fan" filter inside that the fuel flows through. Looking on line, I see most of the in line fuel filters are just a mesh screen inside a plastic tube... does it matter? My one concern with the cardboard fan filter thing is will it let the fuel/oil flow through it freely, or will it restrict the flow too much since the engine doesn't have a fuel pump and just works off of vacuum pressure?

There is a marina place a ways away, so if I HAVE to have the proper fuel line and filter, I can drive and go get them, but it is a fair bit further away than the local auto shop.

Thanks for any advice!

 

[Chris1956]

Re: Adding an in-line fuel filter

5/16" fuel line is a bit marginal. I would use 3/8". The black reinforced neopreme stuff is OK. An inline filter is good for dirt, but doesn't trap water. A water seperator is a better idea. They are a few more $$ however.

 

[d.boat]

Re: Adding an in-line fuel filter

5/16" fuel line is a bit marginal. I would use 3/8". The black reinforced neopreme stuff is OK. An inline filter is good for dirt, but doesn't trap water. A water seperator is a better idea. They are a few more $$ however.

Is there any reason to have an inline filter if you have a good water separator?

 

[Home Cookin']

Re: Adding an in-line fuel filter

don't use the cardboard filters in a boat; the ethanol can eat them up and spit them into your jets.
There is probably a filter in the motor; look for a place where the fuel line goes into a round plastic housing and another comes out. There is a screen in there to catch debris.

The fuel/water seperator is also a filter and a relatively new addition to boating, thanks to ethanol. You want one.

Not everything automotive transfers to marine applications.

Good to hear you're replacing your fuel lines, essential due to ethanol as well as age.
While you're in there, look over your wiring. Some of the older merc's have cloth-covered wiring that sheds its insulation, and then it can arc out against the block.

Keep your fuel fresh. Best way is to do a lot of boating. Ask your girls; they'll agree.

 

[Brewman61]

Re: Adding an in-line fuel filter

Is there any reason to have an inline filter if you have a good water separator?

AFIK, a water seperator is also a filter. The one on my Merc 4.3 MPI is, anyway. In fact somewhere I read that Mercury pretty much says to definately not use an inline in conjunction with the water seperating filter, at least on my engine.

 

[d.boat]

Re: Adding an in-line fuel filter

AFIK, a water seperator is also a filter. The one on my Merc 4.3 MPI is, anyway. In fact somewhere I read that Mercury pretty much says to definately not use an inline in conjunction with the water seperating filter, at least on my engine.

That's the way my 200 hp Johnson is set up - water sep. filter only. I can't imagine that an inline filter would add anything to what that big filter does, except the chance for a fuel restriction. But I was wondering.

 

[foodfisher]

Re: Adding an in-line fuel filter

Inline filter just before the carbs will catch anything that could foul the carbs. IE: disentegrating hoses.

 

[edwardh1]

Re: Adding an in-line fuel filter

Yamaha says on web site 10 micron filter, plus a water seperator . They say 10 micron is very fine (it is) so they say to carry a spare.

Mercury web site says more filters will damage the engine.

who to believe?

 

[dingbat]

Re: Adding an in-line fuel filter

Yamaha says on web site 10 micron filter, plus a water seperator. They say 10 micron is very fine (it is) so they say to carry a spare.

Mercury web site says more filters will damage the engine.

who to believe?

Different motors, Different fuel pumps, Different fuel requirements.

Obviously, OK on a Yammie but not so good if you own a Merc.

 

[j_martin]

Re: Adding an in-line fuel filter

On my V6 merc, I discarded the screen type filter between the fuel pump and carbs, and installed a Racor 60 GPH fuel filter/water seperator between the tank and the primer bulb.

I'v had nothing but good from the setup, hundreds of gallons of fuel.

 

[MercGuy]

Re: Adding an in-line fuel filter

I bought a Sea Ray with a 115 2+2 Merc in 1999.

Within 3 days of ownership I cut the fuel line just before the primer bulb and installed a cheap Fram fuel filter #3G. I replace the filter every year and carry a spare in my toolbox.

Never had any problems with this setup, and it gives me peace of mind.

 

[edwardh1]

Re: Adding an in-line fuel filter

I bought a Sea Ray with a 115 2+2 Merc in 1999.

Within 3 days of ownership I cut the fuel line just before the primer bulb and installed a cheap Fram fuel filter #3G. I replace the filter every year and carry a spare in my toolbox.

Never had any problems with this setup, and it gives me peace of mind.

Yamaha now sez on their web site to use a smaller filter due to ethanol cleaning junk off the fuel system- 10 micron, most car filters are 50 or so.

 

[dingbat]

Re: Adding an in-line fuel filter

Yamaha now sez on their web site to use a smaller filter due to ethanol cleaning junk off the fuel system- 10 micron, most car filters are 50 or so.

Your fooling yourself if you think anything about 10 microns is doing any good.

Yamaha is having a lot of problems with the VST clogging up even with 10 micron filters. A lot of guys are now running 2 micron filters.

 

[edwardh1]

Re: Adding an in-line fuel filter

2 is kinda small, maybe they need to redesign the VST - whats a vst?

 

[d.boat]

Re: Adding an in-line fuel filter

...The fuel/water seperator is also a filter and a relatively new addition to boating, thanks to ethanol. You want one.....

Nah, we've been using them around here since I bought my first outboard in 1986, and it was a standard must-have then, meaning they'd been around forever. But you're right - I can't imagine why anyone would NOT have one. I suppose if you're doing close-in stuff on a well used lake where a fuel problem only means a long paddle or quick easy tow. But anywhere else, especially with a built in tank, they should be standard rigging.

 

[dingbat]

Re: Adding an in-line fuel filter

2 is kinda small, maybe they need to redesign the VST - whats a vst?

Vapor Seperator Tank. When your working with high pressures and vapor sperators, 2 microns isn't all that small.

http://www.yamaha-motor.com/outboard/feat_hpdi_2006.aspx

 

[robert graham]

Re: Adding an in-line fuel filter

For an old Merc with carbs, buy the water/fuel seperator(walmart $27), install on transom with 2 screws, between primer bulb and motor, hook up MARINE fuel lines with clamps, you'll be set to go. This unit does a great job of filtering/seperating fuel, just every now and then unscrew cartridge, dump out water/crud/dirt, re-install and good to go again! Works like a charm!

 

[dingbat]

Re: Adding an in-line fuel filter

install on transom with 2 screws, between primer bulb and motor

A water separating filters work on gravity and therefore must to be installed on the suction side of the system. Putting the filter after the primer ball puts them on the pressure side when you pump the ball. The primer may actually push the water out of the filter and into the system. Not good.

Carry a spare filter and filter wrench on-board at all times. Change the filter every 100 hours or once a year, whichever comes first. If you want to get fancy you can install a vacuum gauge on the filter head that will tell you when it?s time to change the filter. With filters running $22 a piece, I?m not blinding changing them out because it?s ?time?.

 

[robert graham]

Re: Adding an in-line fuel filter

The primer bulb pumps the gas into the top of the seperator and it exits from the top, so how can it pump the water from the bottom and out the top? And I use the primer bulb to refill my seperator cartridge after I dump it.
Where's the problem?