Fuel Questions

[Splash]

Hi Team.

Just got the Fuel 3100 Fuel Flow Meter (with transducer) and need some help..

Manual states: "...The action of inserting an in-line fuel transducer creates back pressure in the engine's fuel delivery system...."
Q1 - How do I ensure excessive back pressure is not created in this instance?

I have a single OB with two 100L fuel tanks on board (which are not plumbed together).
Q2 - One tank already has fuel filler access from outside. What is the best and safest way to fill the send tank - without lifting it in and out of boat?

With the Fuel 3100 FFM, I want to measure fuel economy.
Q3 - Which speed instrument is best used in this application - paddlewheel (STW) or GPS (SOG)?


I want to have my fuel tanks going through the one primary fuel filter (which is before the in-line fuel transducer). When first tank empties, I want to be able to switch over to the second tank.
Q4 - Best and safest way to turn off empty tank line and turn on second full tank (some sort of valve or something)?

Would appreciate your help in this matter.

Splash

[Hamish73]

Hi Team.

Just got the Fuel 3100 Fuel Flow Meter (with transducer) and need some help..

Manual states: "...The action of inserting an in-line fuel transducer creates back pressure in the engine's fuel delivery system...."
Q1 - How do I ensure excessive back pressure is not created in this instance?

I have a single OB with two 100L fuel tanks on board (which are not plumbed together).
Q2 - One tank already has fuel filler access from outside. What is the best and safest way to fill the send tank - without lifting it in and out of boat?

With the Fuel 3100 FFM, I want to measure fuel economy.
Q3 - Which speed instrument is best used in this application - paddlewheel (STW) or GPS (SOG)?


I want to have my fuel tanks going through the one primary fuel filter (which is before the in-line fuel transducer). When first tank empties, I want to be able to switch over to the second tank.
Q4 - Best and safest way to turn off empty tank line and turn on second full tank (some sort of valve or something)?

Would appreciate your help in this matter.

Splash

Q1. depending on the engine. Unless you have a massive engine, or 2 engine with marginal fuel hoses, I wouldnt expect a problem. I wouldnt expect a manufacturer to make a product that leans out engines in the top end due to fuel starvation. I gues that section of the manual is more of a 'disclaimer' than anything else.
If you engine has an electric fuel pump, you could disconnect the outlet hose from the fuel pump and measure before and after fuel flow to see if there is a restriction. The only other option I can see is to do a WOt run, cut the ignition and pull out the plugs and inspect for a lean condition. No lean condition = she'll be right.

Q2 see Q4. Open the valve when filling and the tanks will both fill. The crossover pipe and valve will have to be reasonably large, as will the breather on tank 2
Q3 GPS definately. paddlewheel is effected by current
Q4 I would install a fuel spec ball valve between tank 1 and 2. When 1 is empied, open the valve which will allow fuel to flow to tank 1, being supplied to engine via tank 1 filter.

I have quite a few years of performance engine experience, but I'm no marine engineer.... so I'd seek professional advise, but this is what I'd do.

[FNQCairns]

Hi Splash,

Q number 1 will not apply to your application, boat not long enough and max height of fuel line above pump not high enough.

Q2. Unsafe to do anything else but lift it out unless you have a filler plumbed from outside and also breathers plumbed to outside.

Q3. GPS nothing else is acurate in a repeatable way in comparison.

cheers fnq

[Chimo]

Leaving aside for others all but Q 4
Peter Webster and Ruth Cuunningham in the Sept 2006 no 123 Fisherman and Boatowner p 51 have given a useful account of their method of dealing with multiple fuel tanks and the method of linking them up. It would be worthwhile having a look at their solution, elements of which may well suit you too.

Chimo

[Roughasguts]

Splash where you been ? working hard I hope.

Mate I would have two seperate fuel water separators on for each tank, both
join at a Y piece with a tap on each side, to run one with the other off, or run both at the same time.

On the single line comming out of the Y' piece the fuel tranducer goes, sounds easy doesn't it.

Do the same with the fuel tank filler Y' piece at the fuel cap one line each goes to the fuel tanks, the single line, the fuel cap, should all work provided the fuel filler nozzle can slot in to each side of the Y' piece at the filler cap.

Your fuel breather hose should have a few loops coiled in to it just before the outlet vent, acts as a bit of a water trap, hopfully stopping condensation.

[Splash]

Thanks Boys.

This is going to need a bit more planning on my behalf (hooking up both tanks) - SOme greeat ideas with different viewpoints.

Regarding Q1 - For those those who are not aware - my OB is 110HP 1989 OMC [non-overheated version;-)] - just to confirm - no need to worry about excessive back pressure?

Q2 - Has anyone lifted a 100L fuel tank into a boat?

Q3 - Would my garmin 292C SOG signal be able to plug into the NAVMAN Fuel3100 for speed capture - compatilibility? and I thouhgt STW better represented true speed of boat - as opposed to SOG??


Q4 - Any ideas on spec. I need for a fuel spec ball valve? Am I silly to suggest having a fuel tank (raised from floor) in the bilge area just in front of transom? Chimo - can u possibly scan that article through on a PM? Guts - Is a water/fuel separator the primary fuel filter and I presume you are talking about two(2) separate 'Y' connections?

GUTS - Yeah - working hard, new job, new life, etc..been pretty wet up here and hope to get amongst the sailfish and small black marlin come July-August..

Good to hear you guys are still in loop and are still prepared to answer my queries...really appreciate it!

Splash!

[Roughasguts]

Hi Splash, Q2 yep lifted out me emty 85 litre tank out me boat bloody heavy, couldn't do it full of fuel.

Nah just one Y' piece same as fuel line diameter for the two out let hoses that come out of each fuel water seperator, BIAS have ones with the taps installed.

The remaining out let from the Y' piece goes to your motor with the tranducer in the middle some where.

Oh and one big Y' piece for the petrol filler cap, someone could make it up for you at work in Stainless steel. Yeah I have strange ideas.

But that extra fuel tank I would rather have up forward of your existing tank just to balance the weight better on the water. Then you have to consider tow ball weight as well.
But I guess there's not much in the way of RTA inspectors up there, to ping you on Max trailer weights.

[Chine]

G'Day Splash,

QU3...GPS

QU4......

I have just gone through an exercise of plumbing a spare 25ltr tank into my existing 85ltr inbuilt fuel system and used a 10mm, brass body, three way valve from Bias (Cat. No.4854 $29.90)...... this side of the existing fuel/water separator. Very successful to date.

Best of luck.

Chine

[Roughasguts]

Chine so how do you fill that 25 litre tank.
Do you have a seperate filler ?
Or does it feed through via the fuel line.

I wouldn't mind having a separate 25 litre tank forward of the 85 litre tank I got.
Think it would do wonders for stopping the stale fuel issues, on short sparse trips and better to have more weight forward, my tub way to heavy in the arse in my opinion.

[Splash]

Thanks Guts and Chine.

Guts - I will now retain my original plan of underfloor 2nd fuel tank front half of boat..

Regarding trailer - You may recall, I also upgraded my trailer (with help of my twin) last year - and put on a 1.4t rated axle, new wheels and brakes. Fully loaded weight on trailer (with extra 100kg of fuel) would come to around 1200kg..I believe. (Fingers crossed.)

To confirm at fuel filler nozzle: I don't understand when you say "...provided the fuel filler nozzle can slot in to each side of the Y' piece at the filler cap..."??

Is a water/fuel separator the primary fuel filter?

Hamish - What is the specification of the fuel spec ball valve you referred to?

Chine - will check out bias on Cat. 4854..thanks

Splash

[Chine]

Chine so how do you fill that 25 litre tank.
Do you have a seperate filler ?
Or does it feed through via the fuel line.

I wouldn't mind having a separate 25 litre tank forward of the 85 litre tank I got.
Think it would do wonders for stopping the stale fuel issues, on short sparse trips and better to have more weight forward, my tub way to heavy in the arse in my opinion.

G'Day RAG,

This is exactly why I went down this route......my DF 70 4S Suzi was using so little fuel that invariably the centre tank went stale and I got fed up with turfing 85lts into the mowers (or elsewhere).

I now keep the centre tank permanently full as an emergency supply only (with the view that at least I can get home on reduced revs) and run fresh 95 RON via the 25ltr which is hard plumbed and stowed for'd (cuddy cabin between the two berths). I normally consume between 15~20ltrs. When filling, I detach the fuel line, pull the tank aft and fill inside the boat. This setup also addresses the problems with filling a permanent centre tank in a Signature (subject of another thread).

Must fess up and say that I am far happier knowing that fresh fuel is going through every time.

Cheers

Chine

The centre (emergency) tank will be replenished on a regular basis.

[Splash]

Great aspect Chine - will certainly consider this in my travels as well!

Still not clear on two(2) points -
(1) If your center tank is permanently full - fuel will still go stale will it not?
(2) DO u take out the 25L tank out of boat to fill? If not, how do you manage to climb into the boat with a fuel dispenser connected to the fuel bowser?

Splash

[Roughasguts]

Splash yep the fuel water separator is the primary fuel filter, cost about 130 bucks each made by Racor, Not Ryco. I think there is another brand out there much cheaper for the replacable filters, in the Racor brand there around 90 bucks.

Yeah trying to explain my Y' piece filler Hmmm... try to imagine when you take your petrol filler cap off and look inside down the guts of the Y piece you will see one pipe spread in to two pipes.

If you stick the bowser nozzle in there you should be able to point it in either direction as to which tank your going to fill, EG: left side or right side.

I think it should work well.

[Roughasguts]

Hi Chine yeah I have a signature as well, same fuel filling problem if I move the existing tank forward I would have the fuel filler pipe sticking up in the way of me floor, plus a slower fill. Yeah I should go this way and get a placcy 30 litre tank and put under the floor in front of the existing one.

Me average trip is 30 litres, which is around 30 miles. So I figure if I drain me big tank again fuel must be 4 months old by now, put 30 litres in it and keep the placcy for reserve. And after a month dump the petrol from the placcy tank in the car. Should solve all my fresh fuel and boring syphoning concerns when I use the boat.

Cheers.

[Chine]

Great aspect Chine - will certainly consider this in my travels as well!

Still not clear on two(2) points -
(1) If your center tank is permanently full - fuel will still go stale will it not?
(2) DO u take out the 25L tank out of boat to fill? If not, how do you manage to climb into the boat with a fuel dispenser connected to the fuel bowser?

Splash

Splash,

1. Indeed it will and I am going to keep a careful eye on how often I actually use it to determine how often I replenish it. I reiterate......this supply is for emergency use only. It may well be that I find that my normal usage elevates to say 30ltrs/trip in which case, I will replace the 25ltr tank with a larger unit. The other problem I have with the 85ltr plastic tank (besides the difficulty of trying to fill it) is that it is unbaffled and creates free surface when partially filled. Very detrimental to lateral stability.

2. No. I guess it is a similar scenario to all other boats who use portable tanks. In my case I reach across from inside the boat and fill the tank.

Trying to improve a poorly designed fuel system and keep my engine out of the workshop.........

Regards

Chine