Inline fuel filter for an I/O engine

40 year old boat with metal fuel tank in bow. Yes I know it needs to be replaced, it will have to be custom built though because size does not match anything I have found yet as a stock item. Top half of the boat will have to come off to get to the tank, all this will happen someday, maybe...

What I want to do right now though, is replace the fuel pickup without a screen at the inlet, and put an inline coarse filter between the tank and the anti-siphon valve to keep the valve from crudding up, and allow me to see how much debris is coming from the tank, if any. I am not particularly interested in the water separating versions (I am fully versed on the hygroscopic nature of ethanol, but this is not a part of the equation). Does anyone know why something like this Clear View In-Line Fuel Filter - Moeller 033319-10 - iboats says it is for outboard use only? Or are there other options other than water separators?

Re: Inline fuel filter for an I/O engine

That filter should work fine. Personally, I use an el cheapo Fram inline filter from Wally World as I'm still figuring out how to mount my new water sep filter. Been working just fine for particulates.

Re: Inline fuel filter for an I/O engine

mikecrof said:

I am not particularly interested in the water separating versions (I am fully versed on the hygroscopic nature of ethanol, but this is not a part of the equation). Does anyone know why something like this Clear View In-Line Fuel Filter - Moeller 033319-10 - iboats says it is for outboard use only? Or are there other options other than water separators?

Click to expand...

It's because of ABYC and USCG requirements.

Those types of filters are only intended for OPEN engine compartment applications (like an outboard motor) .

I/O's have enclosed compartments and the clear type inline filters don't meet USCG regs.


You need to use a filter like the following.
Fuel Water Seperator Assembly for Johnson/Evinrude, Volvo Penta, Mercruiser, OMC Sterndrive/Cobra, Mercury/Mariner, Yamaha Outboard - Sierra 18-7965-1 - iboats


You can buy it right here on iBoats too...


Regards,


Rick

I am not particularly interested in the water separating versions (I am fully versed on the hygroscopic nature of ethanol, but this is not a part of the equation).

Click to expand...

Um, Let me also add that that unless you're not operating your boat in water, It IS absolutely part of the equation! and it has NOTHING to do with ethanol.....

This is why ALL marine manufacturers install water separating filters on all their boats nowadays!!

Re: Inline fuel filter for an I/O engine

mikecrof said:

40 year old boat with metal fuel tank in bow. Yes I know it needs to be replaced, it will have to be custom built though because size does not match anything I have found yet as a stock item. Top half of the boat will have to come off to get to the tank, all this will happen someday, maybe...

What I want to do right now though, is replace the fuel pickup without a screen at the inlet, and put an inline coarse filter between the tank and the anti-siphon valve to keep the valve from crudding up, and allow me to see how much debris is coming from the tank, if any. I am not particularly interested in the water separating versions (I am fully versed on the hygroscopic nature of ethanol, but this is not a part of the equation). Does anyone know why something like this Clear View In-Line Fuel Filter - Moeller 033319-10 - iboats says it is for outboard use only? Or are there other options other than water separators?

Click to expand...

Ayuh,... The canister type fuel filters do the Whole job, Safely,....

Forget 'bout what yer lookin' at, as Rick says, it's Wrong,...

The canister will trap any rust, 'n crud, 'n ya inspect it by dumpin' it's Contents into a clear jug,...

'n the anti-siphon valve it mounted To the tank, not downstream somewhere,...

Re: Inline fuel filter for an I/O engine

HT32BSX115 said:

This is why ALL marine manufacturers install water separating filters on all their boats nowadays!!

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Huh - not sure what kind of boats you are buying, but I've never seen one stock on any runabout or ski boat.

Re: Inline fuel filter for an I/O engine

oldjeep said:

Huh - not sure what kind of boats you are buying, but I've never seen one stock on any runabout or ski boat.

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Don't know about outboards....... But since we're in a Mercruiser (I/O) forum.........Here's what I got from the Mercruiser FAQ...

Should I add an additional fine-micron filter to the system to prevent debris from entering the engine?

The addition of another filter to the system will create another possible flow restriction that can starve the engine of fuel. Mercury already provides the appropriate level of filtration to protect the engine from debris.


What kind of spare parts should I carry on my boat for my MerCruiser?

Some suggested items would include a floating prop wrench, a spare prop and attaching hardware, spark plugs, belt(s), oil, power trim and steering fluid, High Performance gear lube, water separating fuel filter, and appropriate fuses.

Click to expand...

Sort of makes me think that Mercruiser has a water separating filter on their engines.......They might not have had them in the past on all of their engines (I know I installed one on a mid 90's Bayliner with a Merc 3.0L engine)

No matter.....you should have one anyway. Is your point that since you don't see them on all the boats you're talking about, they're not needed?

Re: Inline fuel filter for an I/O engine

HT32BSX115 said:

Um, Let me also add that that unless you're not operating your boat in water, It IS absolutely part of the equation! and it has NOTHING to do with ethanol.....

This is why ALL marine manufacturers install water separating filters on all their boats nowadays!!

Click to expand...

Sorry, I was trying not to muddle the question. I have a water sep in the engine compartment, but my problem is that the screen on the pickup is old/crudded (and the pickup is copper with a brass elbow, not plastic/aluminum like everything now) as well as possibly some issues with the metal tank, and the anti-siphon valve has also locked up. So short of purchasing a custom tank and separating the hull to replace it, I need to get some type of small filter in between the tank and the anti-siphon valve to see what is going on with the fuel coming out of the tank, and to keep from introducing any sediment into the fuel lines or pump filter. Now in addition, the boat has set for a couple of years, I put it in storage and foamed the cylinders, etc. so it started up pretty good off of a portable tank, but I went ahead an rebuilt the carb because it is so easy to do. I also left it with a full tank of gas to try and keep the tank from developing any rust. Obviously, I have drained the old gas, and I did my best to orient the boat and siphon tube such that I pulled out as much sediment as possible during the draining of the tank.

Back to the inline filter, I talked with a Moeller rep today and the reason it says outboard only is because it did not meet the standards for the below deck fire test. I have since found one by Sierra that seems to have the proper rating and I have sent them an e-mail to see if it will work in this application.

Above all, this is not a permanent installation, I am only doing it to monitor the fuel for the first few tanks of gas, to see if there are really issues with the tank, or if it is generally ok.

Thanks for all the replies and input on the subject!

Re: Inline fuel filter for an I/O engine

mikecrof said:

Sorry, I was trying not to muddle the question. I have a water sep in the engine compartment, but my problem is that the screen on the pickup is old/crudded (and the pickup is copper with a brass elbow, not plastic/aluminum like everything now) as well as possibly some issues with the metal tank, and the anti-siphon valve has also locked up. So short of purchasing a custom tank and separating the hull to replace it, I need to get some type of small filter in between the tank and the anti-siphon valve to see what is going on with the fuel coming out of the tank, and to keep from introducing any sediment into the fuel lines or pump filter. Now in addition, the boat has set for a couple of years, I put it in storage and foamed the cylinders, etc. so it started up pretty good off of a portable tank, but I went ahead an rebuilt the carb because it is so easy to do. I also left it with a full tank of gas to try and keep the tank from developing any rust. Obviously, I have drained the old gas, and I did my best to orient the boat and siphon tube such that I pulled out as much sediment as possible during the draining of the tank.

Back to the inline filter, I talked with a Moeller rep today and the reason it says outboard only is because it did not meet the standards for the below deck fire test. I have since found one by Sierra that seems to have the proper rating and I have sent them an e-mail to see if it will work in this application.

Above all, this is not a permanent installation, I am only doing it to monitor the fuel for the first few tanks of gas, to see if there are really issues with the tank, or if it is generally ok.

Thanks for all the replies and input on the subject!

Click to expand...

Ayuh,... The anti-siphon valve is at the top of the tank,...

How are ya gonna put that filter between 'em,..??

If you've got a Rotten steel tank, abandon it, 'n use a remote tank, til ya find the time, 'n funds to replace the in hull tank,...

Re: Inline fuel filter for an I/O engine

Just got done going through the rotten tank thing. Best thing I did was pulling it out. If your looking at filters I will echo the other comments about the outboard filter and throw in that that thing looks suspiciously close in construction to the ones made by Spectere at the auto parts store and they are notorious for leaking. If you are just trying to find out how much crud is coming out, why not just cut open your current filter and look?

Re: Inline fuel filter for an I/O engine

Or at least shake/dump the filter contents into a clear container or bowl and see what comes out.

Re: Inline fuel filter for an I/O engine

Bond-o said:

How are ya gonna put that filter between 'em,..??

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As follows: (MIP is Male Iron Pipe and FIP is Female Iron Pipe if anyone is not familiar with plumbing terms, also other than the pickup tube, all fittings are brass)
1) 5/16" copper line pickup tube sweat soldered into a 1/4"MIP brass 90deg elbow with a 1/4"FIP out. (This is identical to the existing pickup tube and fitting)
2) 1/4"MIP to 3/8" hose barb into the elbow
3) Small section of 3/8" fuel hose
4) Inline fuel filter
5) Small section of 3/8" fuel hose
6) 3/8" hose barb to 1/4"FIP direct attached to anti-siphon valve which has 3/8" barb to main line going back to fuel pump

The 1/4"MIP on the 90deg elbow screws into the bung hole on the steel tank. I estimate the entire length from elbow to main fuel line to be about 9". All oriented horizontally, and above the level of the fuel tank.

Bond-o said:

If you've got a Rotten steel tank, abandon it, 'n use a remote tank, til ya find the time, 'n funds to replace the in hull tank,...

Click to expand...

Don't know if tank is rotten, that is the point of the investigation. Also, don't have a good remote tank, so would have to invest funds there that could go to a new tank if I can get some more time out of this one. There was enough sediment/debris that came out from the siphoning, in addition to the frozen existing anti-siphon valve, for me to be concerned about the condition of the tank. It has not leaked, and my father, the previous owner (it was purchased by him new back in 1972) says he pulled the tank about 15 years ago and had it boiled out at a radiator shop. Exterior wise the tank looks in good condition. (Yes he could have replaced it when he had it out, but $50 at the radiator shop probably sounded better than $500+ for a new custom tank, either way there is nothing that can be done about that now other than to save up for one if I am going to replace it in the future.)

Thanks again for the continued input!

Re: Inline fuel filter for an I/O engine

funk6294 said:

...that thing looks suspiciously close in construction to the ones made by Spectere at the auto parts store and they are notorious for leaking.

Click to expand...

I assume you mean the Moeller filter?

funk6294 said:

If you are just trying to find out how much crud is coming out, why not just cut open your current filter and look?

Click to expand...

funk6294 said:

Or at least shake/dump the filter contents into a clear container or bowl and see what comes out.

Click to expand...

I have thought of that, just thought a visible glass filter might be more convenient. Finding out that may not be the case...:blue:

Re: Inline fuel filter for an I/O engine

mikecrof said:

As follows: (MIP is Male Iron Pipe and FIP is Female Iron Pipe if anyone is not familiar with plumbing terms, also other than the pickup tube, all fittings are brass)
1) 5/16" copper line pickup tube sweat soldered into a 1/4"MIP brass 90deg elbow with a 1/4"FIP out. (This is identical to the existing pickup tube and fitting)
2) 1/4"MIP to 3/8" hose barb into the elbow
3) Small section of 3/8" fuel hose
4) Inline fuel filter
5) Small section of 3/8" fuel hose
6) 3/8" hose barb to 1/4"FIP direct attached to anti-siphon valve which has 3/8" barb to main line going back to fuel pump

The 1/4"MIP on the 90deg elbow screws into the bung hole on the steel tank. I estimate the entire length from elbow to main fuel line to be about 9". All oriented horizontally, and above the level of the fuel tank.



Don't know if tank is rotten, that is the point of the investigation. Also, don't have a good remote tank, so would have to invest funds there that could go to a new tank if I can get some more time out of this one. There was enough sediment/debris that came out from the siphoning, in addition to the frozen existing anti-siphon valve, for me to be concerned about the condition of the tank. It has not leaked, and my father, the previous owner (it was purchased by him new back in 1972) says he pulled the tank about 15 years ago and had it boiled out at a radiator shop. Exterior wise the tank looks in good condition. (Yes he could have replaced it when he had it out, but $50 at the radiator shop probably sounded better than $500+ for a new custom tank, either way there is nothing that can be done about that now other than to save up for one if I am going to replace it in the future.)

Thanks again for the continued input!

Click to expand...

Ayuh,... those 2 small hoses, Completely defeats in purpose of the anti-siphon valve,....

Ya may as well just toss it overboard,...

Re: Inline fuel filter for an I/O engine

Bond-o said:

Ayuh,... those 2 small hoses, Completely defeats in purpose of the anti-siphon valve,....

Ya may as well just toss it overboard,...

Click to expand...

Maybe I'm missing the point of it then. My understanding is that the valve keeps fuel from siphoning to a point lower than the tank fuel level, such as the bilge if there is a breach of the fuel system either up or down stream of the valve. The valve will open under vacuum from the fuel pump, but not just from the weight of the fuel in the line. If there is a leak prior to the valve, then any fuel in that portion (before the valve) will be released.

Is my understanding correct or am I missing something?

Re: Inline fuel filter for an I/O engine

mikecrof said:

Maybe I'm missing the point of it then. My understanding is that the valve keeps fuel from siphoning to a point lower than the tank fuel level, such as the bilge if there is a breach of the fuel system either up or down stream of the valve. The valve will open under vacuum from the fuel pump, but not just from the weight of the fuel in the line. If there is a leak prior to the valve, then any fuel in that portion (before the valve) will be released.

Is my understanding correct or am I missing something?

Click to expand...

Your thinking is correct. That is the purpose.

I just had to replace my anti siphon valve. It would stick closed (default).

Even though I have a Volvo, it is very similar-fuel delivery wise.

I went with a "spin on" water seperating filter unit right after the tank. I eliminated the fuel pump bowl filter. I left the in carb (Holley) "rock strainer" in place.

I carry one extra spin on filter. I can change it in two minutes.

Re: Inline fuel filter for an I/O engine

Fleetwin said:

Your thinking is correct. That is the purpose.

I just had to replace my anti siphon valve. It would stick closed (default).

<SNIP>

I carry one extra spin on filter. I can change it in two minutes.

Click to expand...

Thanks for that verification. So based on that understanding, here is what I see happening if there is a breach of the system before the valve. Any fuel in the elbow or pickup tube will drain back into the tank, any fuel in the small hose segments or filter could leak out onto the top of the tank. No fuel will siphon from the tank through the breach as the elbow and valve are higher than the tank fuel level and there is an air gap now between the elbow and the valve. Any fuel in the line downstream of the valve will stay in the line as the valve will keep it from coming back up out of the valve although I don't think this would be possible as the valve is the highest point in the system.

Thanks also for the idea on relocating the existing water sep. That may need to be an option at some point.

Re: Inline fuel filter for an I/O engine

mikecrof said:

Thanks for that verification. So based on that understanding, here is what I see happening if there is a breach of the system before the valve. Any fuel in the elbow or pickup tube will drain back into the tank, any fuel in the small hose segments or filter could leak out onto the top of the tank. No fuel will siphon from the tank through the breach as the elbow and valve are higher than the tank fuel level and there is an air gap now between the elbow and the valve. Any fuel in the line downstream of the valve will stay in the line as the valve will keep it from coming back up out of the valve although I don't think this would be possible as the valve is the highest point in the system.

Thanks also for the idea on relocating the existing water sep. That may need to be an option at some point.

Click to expand...

Yes, you have the idea.

I recommend a 10 micron fuel/water seperator between the engine and the tank. That will stop anything harmful.

There are many available here on iboats. Buy a couple extra filters if you think your tank is suspect. Filters are easy to change if you put the housing in a convenient place. Spin on, spin off.

Also, Double clamp every fuel line. Use the right size clamps only in Stainless Steel.

Re: Inline fuel filter for an I/O engine

"Also, Double clamp every fuel line."

Negative. Use fuel injection clamps if you are worried. Regular worm gear clamps are fine, and more than enough for the low fuel pressures you have.

Re: Inline fuel filter for an I/O engine

Confirm - Anti-siphon valve MUST BE directly attached to the fuel tank.

If you feel the tank is corroded one method of cleaning is use an electric fuel pump (large), pump the fuel out thru a canister filter and discharge directly back into the fill port. Keep recycling the fuel. You could remove the tank sending unit and drop a weighted hose in, either move it around or jack and block the trailer such to have a low spot in one corner of the tank. agitate the craft to stir up all the muck then jack /block quickly so the agitated muck can settle to the low side.

Second method, if the tank is corroded, remove the tank, drain, clean, allow to air dry completely. Pour in a quart or more of fuel tank sealer, tip tank to distribute coating covering all surface. Allow to air dry. Reinstall and forget about it, cured.

Re: Inline fuel filter for an I/O engine

CharlieB said:

Confirm - Anti-siphon valve MUST BE directly attached to the fuel tank.

Click to expand...

Actually it can have a filter before it. I just found the following link pertaining to this.

Fuel Systems - Manufacturer Requirements

Under 183.568 - Anti-siphon protection, please see item (b) below the box:

"(b) Install an anti-siphon device at the tank withdrawal fitting. The fuel distribution line may then run below the level of the tank top. A filter may be installed between the fuel tank withdrawal fitting and the anti-siphon device."

Also further down under the TO COMPLY WITH THE LAW section, bullet point #3.

"If not, is an anti-siphon device or an electrically operated fuel stop valve installed at the point where the fuel distribution line goes below the fuel tank top level?"

So once I hear back from Sierra on their filter, I will be using that for this application, if they say it is rated for below deck use.

Thanks again to all for quite a discussion!