# Fuel Tank Feed Distance-25hp Merc.



## Rollbar (Oct 20, 2016)

I have a 6gl portable tank that I want to mount up front for ballast reasons (pic below).
I added a 10' 3/8" fuel line to the tanks feed/fuel line and when running 1/2 throttle it did ok. 
When I opened her up it ran good and then I could see I had to pump the primer bulb to keep it going. 
I really would like to mount it up front but since my experience mentioned above, I removed the 3/8 line (except for a short piece) and running the stock length/6'.
Question is:
1. If you are running a forward portable tank, how are you maintaining the fuel feed?
2. Are any of you running a electric pump, if so, what, or what pound pump?
3. If running an electric pump, won't it push to much against the carb and cause a forced flooding of the motor since it is a small outboard (I don't think so but then again I'm not a outboard mechanic?
Thanks,

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Boat
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## Jason Cooper (Dec 6, 2016)

It could be the filter you have on the line. 

Also you have a new epa tank it looks like. I took my cap apart and removed the check valve in it to make it breathe. Also it dont swell up anymore.


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## firecat1981 (Nov 27, 2007)

You have to many joints in the system and need to trouble shoot. None of us run a seperated electric pump. My tank has, if memory serves, 14ft of A1 3/8" fuel line, and I've never had an issue. Take out the short splice, and the lawn mower style fuel filter and try it again.


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## lemaymiami (Feb 9, 2007)

Years and years ago I ran a 16' aluminum skiff (an old Starcraft we built a bonefish interior for -decked front and rear with two portable six gallon tanks all the way forward - so a 13 to 14 foot fuel line to the rear....). The old BoneBreaker had a 55hp Evinrude motor on it and that setup worked just fine...

If your motor isn't getting enough fuel with a longer fuel line - my first check would be to make certain your portable tank is actually breathing properly when you're running. At the first sign it was starving out -I'd loosen your filler cap (leaving it in place...). If that solves your fuel starvation problem you know that your tank isn't venting properly.... Hope this helps -if that isn't your problem then you'll have to check the rest of your fuel line components...

That said, here's a forty year old pic of me on the bow of that skiff....


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## DuckNut (Apr 3, 2009)

As mentioned above. You have an air leak.

My tank is 12' away and not an issue. Just need to crack the fill cap to allow air in, tighten when done.


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## bw510 (Sep 1, 2011)

I just had this issue and found a loose hose clamp and while inspecting the lines I noticed the fuel line was separating on the inside and could have been sucking closed.i haven't ran it yet but I'm sure this fixed it.
Also is the fuel filter completely filling up maybe it's pulling air from that??


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## Rollbar (Oct 20, 2016)

I was thinking of getting rid of the filter since there is one on the motor. I just wasn't sure if the motor could suck that far etc and not use to these new tanks. I'll look and remove that white piece (I think) and go from there. New fuel line all the way through and tight connections. I only use non-ethanol fuel so the lines should be good/month old.
Thanks again,


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## Marsh Pirate (Sep 15, 2016)

If all else fails, try a bigger hose.


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## MooreMiller (Sep 10, 2016)

As long as there is no leaks, your engine should be able to suck fuel through 500 miles of hose if all the hose is at the same height. 

I personally would not feel comfortable running an outboard with only one fuel filter.


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## Rollbar (Oct 20, 2016)

MooreMiller said:


> As long as there is no leaks, your engine should be able to suck fuel through 500 miles of hose if all the hose is at the same height.
> 
> I personally would not feel comfortable running an outboard with only one fuel filter.


Thanks, I'm going to change out the filter to a small 3/8" one that is about the same size as the hose.
I'll try these recommendations hopefully this week.
Thanks again all,


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## No Bait / Lures Only (Apr 10, 2011)

I have a similar situation, 12 portable plastic tank mounted under front deck. Hose is then routed under gunnels to transom thru a canister filter mounted an then up to fuel bulb up at the motor. Probably 15' total length, only thing is as the boat sits for a week it does require me to pump the fuel bulb for a few minutes minimum and choke the engine to crank. This is a 25 hp Yamaha 2006 2 stroke 2 cylinder 2 carbs.


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## WhiteDog70810 (May 6, 2008)

Is the fuel pump working properly? I had this exact problem with my mudmotor. In the end, the wimpy diaphragm fuel pump couldn't overcome the resistance of 14' of 3/8" fuel line and I had to add an electric fuel pump, but outboards generally have a more robust fuel pump than a mudmotor. I checked every mentioned point of failure... ...twice! A bad fuel pump, an air leak, an overly restrictive fuel line or an unvented fuel tank will all look the same; the motor will starve for fuel. You have to work from front to back to find the problem. If the bulb is getting sucked down, the tank may not be venting properly. Let's hope that is the case because it is the easiest fix.

Nate


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## Rollbar (Oct 20, 2016)

WhiteDog70810 said:


> Is the fuel pump working properly? I had this exact problem with my mudmotor. In the end, the wimpy diaphragm fuel pump couldn't overcome the resistance of 14' of 3/8" fuel line and I had to add an electric fuel pump, but outboards generally have a more robust fuel pump than a mudmotor. I checked every mentioned point of failure... ...twice! A bad fuel pump, an air leak, an overly restrictive fuel line or an unvented fuel tank will all look the same; the motor will starve for fuel. You have to work from front to back to find the problem. If the bulb is getting sucked down, the tank may not be venting properly. Let's hope that is the case because it is the easiest fix.
> 
> Nate


Nate, my thoughts as well/overcoming the distance etc.
No the bulb has never sucked flat and I ran 1/2 throttle and no problem w/the cap tight on the tank.
Question, what fuel pump did you use and did you put a fuel pressure regulator in-line.
To others, what pressure does the '94 Merc 25hp 2S need?
Thanks, and to cold to test today


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## WhiteDog70810 (May 6, 2008)

The pump is an electric pump that is attached to the side of the Honda small engine on my mudmotor. It is a whole different creature than an outboard. Mine is actually a "pusher" pump that is supposed to be installed closer to the tank than the motor, but I have it set in a "puller" application and it works. I have no inline fuel pressure regulator. You will not need a remote pusher pump on an outboard, but you do need to ensure your pump is working properly.

Nate


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## ol' superskiff (Oct 22, 2015)

lemaymiami said:


> Years and years ago I ran a 16' aluminum skiff (an old Starcraft we built a bonefish interior for -decked front and rear with two portable six gallon tanks all the way forward - so a 13 to 14 foot fuel line to the rear....). The old BoneBreaker had a 55hp Evinrude motor on it and that setup worked just fine...
> 
> If your motor isn't getting enough fuel with a longer fuel line - my first check would be to make certain your portable tank is actually breathing properly when you're running. At the first sign it was starving out -I'd loosen your filler cap (leaving it in place...). If that solves your fuel starvation problem you know that your tank isn't venting properly.... Hope this helps -if that isn't your problem then you'll have to check the rest of your fuel line components...
> 
> That said, here's a forty year old pic of me on the bow of that skiff....


That's a cool pic captain!


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## DuckNut (Apr 3, 2009)

Rollbar said:


> I was thinking of getting rid of the filter since there is one on the motor. I just wasn't sure if the motor could suck that far etc and not use to these new tanks. I'll look and remove that white piece (I think) and go from there. New fuel line all the way through and tight connections. I only use non-ethanol fuel so the lines should be good/month old.
> Thanks again,


The motor does not really do the sucking. The primer ball does the pushing.


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## Jason Cooper (Dec 6, 2016)

DuckNut said:


> The motor does not really do the sucking. The primer ball does the pushing.


The primer ball is just to prime the system. The motor has a fuel pump to pull the fuel.


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## Rollbar (Oct 20, 2016)

Jason Cooper said:


> The primer ball is just to prime the system. The motor has a fuel pump to pull the fuel.


Yes, looking through the fuel filter you can see the fuel being pulled with out the bulb being pumped.
Bulb prevents back flow to the tank if I understand it right.


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## Rollbar (Oct 20, 2016)

FYI~Cracked open the fuel tanks cap and no problems.
Next to add the 3/8" hose back on and go.
Thanks,


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