# Engine Dying after Fuel/Water Separator Install



## Chad Cohn (Mar 8, 2018)

Installed a fuel water separating filter for my 2010 Merc 90 Opti. Engine starts and idles fine but when I got to WOT the engine just sputters and dies as I getup on plane. I think it is a fuel pressure issue but I wanted to see what the brain trust may know. Please share what you think it may be and how I can remedy the issue.

Thanks,
Chad


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## Smackdaddy53 (Dec 31, 2012)

Probably sucking air or trapped air in fuel system.


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## Chad Cohn (Mar 8, 2018)

Smackdaddy53 said:


> Probably sucking air or trapped air in fuel system.


I only have about 10 gal(28 gal tank I believe) in the boat right now. So should I - 
1) Fill it up completely
if not
2) how can I get the air out?


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## Forcefed (Aug 5, 2016)

You need to check all the hose clamps from when you installed the filter. Make sure they are all tight. Also, if you didn’t replace the fuel hose that runs through the boat, you may have cracked it when cutting and installing the filter, as the lines get brittle over time, or collapse internally and the inner liner doesn’t allow full flow and becomes a restriction as the flow rate increases with engine rpm. You can check by Bypassing parts of the system such as the primer bulb and fuel water separator to find restrictions or air gaps that may be allowing the outboard fuel pump to suck some air.


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## Chad Cohn (Mar 8, 2018)

Hose is in good shape, checked before I cut it. I will check the fittings once again. I'm leaning towards what Smack mentioned and this there is are in the lines somewhere.


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## lemaymiami (Feb 9, 2007)

If you have a screw on type filter, did you put a coat of grease on the washer before installing it? These days the alcohol in fuel can attack the washer (or gasket), and soften it so that you don’t have an air tight seal. If that’s what’s happened you’ll get enough fuel to be able to start and idle- but not enough to get up on plane and run... A slight leak anywhere along your fuel anywhere between tank and motor can cause the same problem...


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## topnative2 (Feb 22, 2009)

and/or....first, make sure u do not have water in the filter......then

get the end of your fuel hose above the gas tank and pointed up and pump the bulb till u think u ran the hose out once...keep an eye on it as u pump looking for a strong continuous flow......reconnect and try her now


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## Cej2525 (Jan 22, 2019)

Plug off the line at the tank. Use a Mightyvac to put a vacuum on the line and see if it leaks off. if it doesn't then the filter assembly may be to much of a restriction or you have a faulty / inefficient pump that deal with the new head pressure. An easy way to check that would be bypassing the filter with a barb fitting and see if the problem is resolved. A Mightyvac can be rented at some auto part stores. Hope this helps.


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## Smackdaddy53 (Dec 31, 2012)

All great advice. Try running a remote tank straight to the outboard. It will indicate if it’s your fuel system in the boat or something under the cowling.


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## lemaymiami (Feb 9, 2007)

Well said Smack... that's the first thing a pro does before getting into messing with the fuel system - make sure it's not the engine with a problem...


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## Chad Cohn (Mar 8, 2018)

Thanks everyone for the input. I'm going to double check fittings, hose clamps, etc. today. Going to re-prime the line and hope for the best. I didn't grease the gasket on the filter but I did rub some 2 stroke oil on it (like when doing an auto oil change). I'm actually running E free fuel right now due to the water in the tank I've already experienced.


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## ryan_riggle09 (Jun 14, 2018)

Had the exact same problem when I Changed fuel water separator on my 40 mercury, Did what topnative2 said was able to push all the air out of the system. Motor ran like normal with no issues after that.


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## Net 30 (Mar 24, 2012)

Had the same problem on my larger boats 150 E-Tec. Turned out to be a defective water separator. If you have the old one put it back on a see if it helps.

My mechanic said he's seen a big increase in defective seps being outsourced from China.


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## Chad Cohn (Mar 8, 2018)

Net 30 said:


> Had the same problem on my larger boats 150 E-Tec. Turned out to be a defective water separator. If you have the old one put it back on a see if it helps.
> 
> My mechanic said he's seen a big increase in defective seps being outsourced from China.


I just installed the setup on the boat as it did not have one at all. I have an extra filter, maybe I'll try that.


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## Chad Cohn (Mar 8, 2018)

ryan_riggle09 said:


> Had the exact same problem when I Changed fuel water separator on my 40 mercury, Did what topnative2 said was able to push all the air out of the system. Motor ran like normal with no issues after that.


I'm hoping that it is that easy for sure. I just want to get out, go fast and catch fish.


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## topnative2 (Feb 22, 2009)

Chad Cohn said:


> I just installed the setup on the boat as it did not have one at all. I have an extra filter, maybe I'll try that.


You may have sucked up a bunch of h2o which will cut the fuel flow down to where u can't go fast...dump it into a jar to see if it is a water issue if it is not a clear bowl model...since u did not have a water separator on it before my money is on this


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## devrep (Feb 22, 2009)

you guys are reminding me that I probably need to change both of mine. I always write the date on a new filter with a sharpie, will need to go check.


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## BassFlats (Nov 26, 2018)

When I install a new water/fuel separator I always fill the new filter with fuel before I spin it on . I've never had a problem with an air bubble.


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## Chad Cohn (Mar 8, 2018)

topnative2 said:


> You may have sucked up a bunch of h2o which will cut the fuel flow down to where u can't go fast...dump it into a jar to see if it is a water issue if it is not a clear bowl model...since u did not have a water separator on it before my money is on this


I drained the tank before I installed the filter setup but I'll double check that too.

On the subject of changing filters, the one that I am using states it is reusable. I thought hat was odd because of what it is used for. I have a second new filter and I may go ahead and just swap filter for now.


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## topnative2 (Feb 22, 2009)

We use to shake the water out when the filter got filled.It is better to get the ones w/ the clear bowl because u can see the water and then open the relief knob and tap it till the water is gone and re-tighten.

The filters can be used for awhile they are pretty tough.


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## topnative2 (Feb 22, 2009)

I had an old T-craft that had a leaky sending unit. And, when the filters got full, I would have to stop and dump the water out so I could "run" again.
Always something........................


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## efi2712micro (Sep 17, 2015)

I just disconnected the fuel line from the tank and saw separation of the inner plastic layer from the core. From the outside, the line looks great!It was put in in 2013 and it looks like time has done a number on it. Now I feel that I need to replace the whole line to prevent down the road issues. Is that a common problem? Could it be what’s happening here?


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## Smackdaddy53 (Dec 31, 2012)

efi2712micro said:


> I just disconnected the fuel line from the tank and saw separation of the inner plastic layer from the core. From the outside, the line looks great!It was put in in 2013 and it looks like time has done a number on it. Now I feel that I need to replace the whole line to prevent down the road issues. Is that a common problem? Could it be what’s happening here?


That’s the number one issue with fuel line that is not ethanol compatible then second is a clogged fuel filter from bits of degraded fuel line restricting the pump. If I were you I’d replace every inch of it or you’ll likely be having more issues in the future.


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## Smackdaddy53 (Dec 31, 2012)

topnative2 said:


> We use to shake the water out when the filter got filled.It is better to get the ones w/ the clear bowl because u can see the water and then open the relief knob and tap it till the water is gone and re-tighten.
> 
> The filters can be used for awhile they are pretty tough.


You can take a clear container to the gas pump and put some gas in it, cap it and shake it up real well then let it sit for a minute and the water and ethanol will separate from the gas and you can really see what’s going in your tank. 
I contemplated getting a 200-300 gallon overhead tank and putting a sight glass at the very bottom with a needle valve to drain off the ethanol and water but ethanol has not plagued my outboard, mower or anything else yet. Just run it and you’ll be fine.


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## efi2712micro (Sep 17, 2015)

Smackdaddy53 said:


> That’s the number one issue with fuel line that is not ethanol compatible then second is a clogged fuel filter from bits of degraded fuel line restricting the pump. If I were you I’d replace every inch of it or you’ll likely be having more issues in the future.


Thanks Smack ... new ethanol compatible line going in! This is new territory for me but nothing better than trial-by- to learn


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## Chad Cohn (Mar 8, 2018)

efi2712micro said:


> I just disconnected the fuel line from the tank and saw separation of the inner plastic layer from the core. From the outside, the line looks great!It was put in in 2013 and it looks like time has done a number on it. Now I feel that I need to replace the whole line to prevent down the road issues. Is that a common problem? Could it be what’s happening here?


This is exactly what happened to mine. I had gotten so tired of messing with it I took it to the shop and let them deal with and do he annual maintenance at that time too. I'm running E-free from here on out even if that means that I am dragging 2-3 5 gal gas cans with me on trips.


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## Chad Cohn (Mar 8, 2018)

Well it appears my engine issues weren't resolved completely. Took it out this weekend and initially it ran great. Fished for a while and decided to run to the other end of the lake and once on plane boom here it goes sputtering again. I'm freaking stumped so I'm going to take it back to the shop and let them figure it out since they told me it was good to go. Considering getting it running and just trading it and taking the hit but at least I would have newer with hopefully less problems.


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## Smackdaddy53 (Dec 31, 2012)

It’s something simple. Almost always is.


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## Chad Cohn (Mar 8, 2018)

Smackdaddy53 said:


> It’s something simple. Almost always is.


I'm sure it is but unfortunately I don't have the time or patience right now.


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## flyclimber (May 22, 2016)

I had something similar, it would die maybe 10-30 seconds after getting on the throttle. The priming bulb was very soft. After I got on plane I continued to prime it while running. I assumed that the engine was getting air locked. Haven't had an issue since.


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## SomaliPirate (Feb 5, 2016)

Chad Cohn said:


> I'm sure it is but unfortunately I don't have the time or patience right now.


Replace the backflow valve deal at the tank and the primer bulb. Both are cheap and easy and just might do it. Also check to make sure the tank vent is clear? People smarter than me chime in, but if the tank isn't vented well it could cause some fuel starvation, right?


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## lemaymiami (Feb 9, 2007)

For those not aware, ethanol compatible fuel lines are clearly marked on the outside of the line continuously ( USCG Type One Acol... etc.) so you can tell they’re safe to use with ethanol. Avoid any mass market retailers (Walmart, etc.). Only buy fuel components from authorized dealers or from solid marine hardware outfits.

By the way, if you ever suspect that your fuel bulb is old or faulty... The one BRP sells is the best of all of them...


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## Smackdaddy53 (Dec 31, 2012)

A collapsed fuel line (the internal liner) can be impossible to troubleshoot. Fuel hose is cheap compared to constantly fighting fuel delivery issues.


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## State fish rob (Jan 25, 2017)

Nothing good happens w Ethanol


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