adding an inline fuel filter.

[Clarko]

Hi all,
If possible, can some please advise if i can add an inline fuel filter to my 1989 mercruiser 5.0lx.
I already have a water separating filter fitted but would like to add an inline filter between the water separator and the tank to protect a fuel flow meter I am about to install.
if this is possible can someone please also provide a part number that can I use?
l
Many thanks for your time and assistance.
regards
Clarkie

 

[San_Diego_SeaRay]

Hi all,
If possible, can some please advise if i can add an inline fuel filter to my 1989 mercruiser 5.0lx.
I already have a water separating filter fitted but would like to add an inline filter between the water separator and the tank to protect a fuel flow meter I am about to install.
if this is possible can someone please also provide a part number that can I use?
l
Many thanks for your time and assistance.
regards
Clarkie

I also installed a Lowrance Fuel Flow meter in my boat. The manual said to definitely install a filter prior to the meter. I read somewhere that plastic filters are a no no on boats. So I ended up buying a generic glass inline fuel filter. I imagine one of those metal Frame inline filters would work just as good. But I kinda liked to see the gas. Works for me.

 

[Clarko]

Thanks San Diego SeaRay,

Does having the second filter cause any issues regarding fuel flow restriction?
cheers

 

[Bondo]

Thanks San Diego SeaRay,

Does having the second filter cause any issues regarding fuel flow restriction?
cheers

Ayuh,...... Welcome Aboard,...... Why add a 2nd restriction point,..??..??

Just put yer transducer after the original filter,.......

'n glass is no more acceptable than plastic in the fuel system of an I/O powered boat,.......

 

[Clarko]

Thanks for the kind welcome and advice Bondo.
after the original filter is a metal pipe and it’s beyond my skill level to safely install the sender in that.
I was hoping for an easier solution in the rubber hose but like you say I’m a bit worried about restricting fuel flow.
thanks again for taking the time to help!

 

[San_Diego_SeaRay]

Thanks San Diego SeaRay,

Does having the second filter cause any issues regarding fuel flow restriction?
cheers

Nope, has not presented any problems. I'm rarely at full throttle, but when I am I've not noticed any fuel delivery issues.

 

[dingbat]

Nope, has not presented any problems. I'm rarely at full throttle, but when I am I've not noticed any fuel delivery issues.

My Garmin GFS-10 fuel flow sensor was supplied with a WIX 33033 (or equivalent) fuel filter.

Running off fore and aft tanks. Have a Racor 10 micron separator and a 20 micron inline at the fuel pump as well.

No fuel restriction to 23+ GPM

 

[San_Diego_SeaRay]

23+ GPM

 

[dingbat]

Opps....... that's 23+ gallons per hour

 

[Clarko]

Great news. Thanks very much for the info San Diego SeaRay.
I will push on with the install I think.
cheers

 

[achris]

Both plastic and glass are forbidden in an inboard engine bay. It MUST be metal. I also have a fuel flow sensor and have installed a genuine Merc water separator as the filter before the sensor. A second filter isn't a problem. At full noise I'm flowing 62LPH... No problems at all.

Bondo I was also looking at installing the flow meter after the engine mounted filter, but it's just not possible.

Chris.......

 

[Clarko]

Cheers Chris.
thats good to know it hasn’t affected the fuel flow.
ive ordered a metal fuel filter and no waiting for delivery.
thanks for letting me know

 

[AKJohne]

I installed a Lowrance in-line paddle wheel sensor on a 5.7 with mechanical fuel pump and water separator filter hard-piped to the carb, I also have a Racor on the transom and ran the line form the tank to that first then to the water separator on the engine. I installed the senor in a vertical section of hose as I think Lowrance indicates it should be in a vertical position.
So far it works excellent, it was very accurate out of the box, however it would typically error slightly (showing less fuel remaining than what was actually in the tank). I re-calibrated last season and it is within a percent or tow, still on the plus side. Even trolling and running the kicker and it still is on the money. Although it fluctuates at low RPM it still averages very accurately. One of the reasons for a filter before the sensor is the potential to restrict fuel if for some reason you sucked up some debris in the line. The filter will catch it first. can supply a photo if that would be helpful.

 

[dingbat]

I installed a Lowrance in-line paddle wheel sensor on a 5.7 with mechanical fuel pump and water separator filter hard-piped to the carb, I also have a Racor on the transom and ran the line form the tank to that first then to the water separator.

Don't get the need for the Racor on the transom if you have a second separator on the motor.

I’ve a simple inline metal filter in front of the flow sensor and 10 micron Racor separator behind.

 

[harringtondav]

So I''ll admit I'm a bit of doof on this thread. But I don't understand the concept of a fuel flow meter. Boat engines are thirsty because they require much power to keep a boat on top of the water. I rely on the tach, speedo, trim, engine sound and my throttle hand to achieve the best performance when I'm underway. ...maybe this gizmo would help optimizing fuel usage....but I'm a skeptical codger, wondering if it's worth the cost and effort.

PS edit. I don't know the particulate specs of the Merc separating filter, but I'm guessing a redundant filter isn't worth the trouble compared to an annual change of the water separating fuel filter spin on.

 

[achris]

So I''ll admit I'm a bit of doof on this thread. But I don't understand the concept of a fuel flow meter. Boat engines are thirsty because they require much power to keep a boat on top of the water. I rely on the tach, speedo, trim, engine sound and my throttle hand to achieve the best performance when I'm underway. ...maybe this gizmo would help optimizing fuel usage....but I'm a skeptical codger, wondering if it's worth the cost and effort.

PS edit. I don't know the particulate specs of the Merc separating filter, but I'm guessing a redundant filter isn't worth the trouble compared to an annual change of the water separating fuel filter spin on.

Most flow meters double as a fuel gauge. And as long as you tell them how much fuel you added to the tank each time, they'll tell how much is left. I also do use mine as a Q&D L/Nm consumption indicator. Granted it's just 'information', usually fuel consumption is dependent of load, speed and weather, most of us are just stuck with whatever it is. but, I'm an information nerd, so I like that...

The reason people are asking about second filters is because since about 1992 all Merc engines come with engine mounted fuel filters, and putting the flow sensor between the filter and the fuel pump is pretty much impossible. And since it's really clear (and for good reason, just ask me :facepalm in the instructions that a filter MUST be mounted upstream of a flow sensor, anyone installing one has little choice but to install a second filter.

Chris.......

 

[Clarko]

G’day AkJohne,
thanks for the feedback on your installation and the accuracy of the lowrance sensor as that’s what I’m going to use.
thanks for the offer of a photo of your setup. I might hit you up again if I can’t get mine to work.
im going to try an inline filter prior to the standard engine mounted filter in the first instance.
to be honest it’s the cheapest and simplest solution at the moment.
Notng you have the Racor gives me extra confidence that should the inline filter cause problems I can still get the setup to work.
thank you for your help!

 

[Clarko]

Dingbat, thanks for your info? Having the setup that I’m looking at. Do you find you have to replace the inline filter more frequently??
Also can you please let me know what inline filter you are using??
thanks heaps

 

[Clarko]

So I''ll admit I'm a bit of doof on this thread. But I don't understand the concept of a fuel flow meter. Boat engines are thirsty because they require much power to keep a boat on top of the water. I rely on the tach, speedo, trim, engine sound and my throttle hand to achieve the best performance when I'm underway. ...maybe this gizmo would help optimizing fuel usage....but I'm a skeptical codger, wondering if it's worth the cost and effort.

PS edit. I don't know the particulate specs of the Merc separating filter, but I'm guessing a redundant filter isn't worth the trouble compared to an annual change of the water separating fuel filter spin on.

G’day harrington dav,

fair question mate.
For my situation it’s less about economy and performance, (though this will be an added benefit) but more a safety factor. My fuel tank capacity isn’t great but I still have to travel a fair distance and although I have a couple of jerry cans as a reserve, I like to know when to call it quits and head for home and hopefully not have to use the Jerry’s. Probably too risk adverse I know but I’m happy being like that.
cheers

 

[harringtondav]

achris , Clarko . Thanks. I understand. I'm an inland Mississippi boater. Even on a long trip the gas docks are abundant. If I was venturing long out of sight of land, I'd have one of these.