Fuel system plumbing question

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
paulga said:
is the female pipe thread welded to a hole on the top of the tank?
if the same hole is used as a source rather than a return, what tank fitting do you install there?
Click to expand...
There is a section of the tank top where thicker aluminum is welded to the top, maybe 4" by 16". At one end of the tank there are four return fittings (two of which are used). At the other end there are four fittings with two for supply lines (with draw tubes). At each end of the tank there is one vent line in one of the fittings. The two supply fittings have tubes (draw tubes) welded to the pipe bushing that reach to within an inch or two of the bottom of the tank.

Each tank has a 1/2" drain valve at the lowest corner on the inboard side of the tank. This is where I connected my fuel polisher / transfer system.

Ted
 
paulga said:
yes, i traced the fuel hoses so I know hose A is fueled from the portside tank.

the genny takes fuel from the starboard side tank and return to the portside tank
the engine takes fuel from the portside and returns to the starboard side

these returns are thin cooper fuel lines that do not have a valve, they are as thick as the cooper line (purple D, to which hose A is tapped) shown in photo 2 and 3 in post #1.

the low pressure by pass valve as i understood, is a strain relief for the polishing pump that will create much higher psi that could render leaks if both return lines are turned off when this pump is turned on. the leak in this thread is likely due to the same reason.
Click to expand...
From the way the system was setup, it appears that the pump is pushing fuel through the Racor filters. The Racors aren't designed for pressure (all though they are rated for some), they're designed to operate in vacuum. Your Facet pump should have been placed after the Racors, pulling fuel through them.

Below is a link to Facet fuel pumps. You will find the maximum pressure (only available on some models) is 8 PSI. They are capable of lifting fuel 24" to the pump. They are a plunger style (piston, spring, and electric coil) pump that simply stops flowing fuel when head pressure (8 PSI) is exceeded.


What through me off was the pump. I was assuming the pump was pulling fuel through the filters, not pushing it through.

Ted
 
O C Diver said:
From the way the system was setup, it appears that the pump is pushing fuel through the Racor filters. The Racors aren't designed for pressure (all though they are rated for some), they're designed to operate in vacuum. Your Facet pump should have been placed after the Racors, pulling fuel through them.

Below is a link to Facet fuel pumps. You will find the maximum pressure (only available on some models) is 8 PSI. They are capable of lifting fuel 24" to the pump. They are a plunger style (piston, spring, and electric coil) pump that simply stops flowing fuel when head pressure (8 PSI) is exceeded.


What through me off was the pump. I was assuming the pump was pulling fuel through the filters, not pushing it through.

Ted
Click to expand...
The bleeding instructions says the racor lid need to be open before the pump is turned on. So the pressure will not build up in the racor unit
 
O C Diver said:
There is a section of the tank top where thicker aluminum is welded to the top, maybe 4" by 16". At one end of the tank there are four return fittings (two of which are used). At the other end there are four fittings with two for supply lines (with draw tubes). At each end of the tank there is one vent line in one of the fittings. The two supply fittings have tubes (draw tubes) welded to the pipe bushing that reach to within an inch or two of the bottom of the tank.

Each tank has a 1/2" drain valve at the lowest corner on the inboard side of the tank. This is where I connected my fuel polisher / transfer system.

Ted
Click to expand...
Are all the 8 pipe bushings screwed/welded onto the 4"x16" plate? 4 returns on one side and 4 supply on the other side of the plate?

Does the boat have two tank vent fittings on each side below the rubrail?
 
paulga said:
Are all the 8 pipe bushings screwed/welded onto the 4"x16" plate? 4 returns on one side and 4 supply on the other side of the plate?

Does the boat have two tank vent fittings on each side below the rubrail?
Click to expand...
There are 2 areas roughly 4" x 16" on top of each tank at opposite ends. So there are 8 fittings on top. The bushings with or without the draw tube determine which are supply and which are return. There is also a Tank Tender tube (determines fuel level) in each tank.

There are two tanks in the boat. Each tank has two vents at opposite ends. The fill pipes and the tank vents are located inside the aft deck area on each side. No fuel spills. No salt water entering the vents. You can hear the tank venting gas through the vents. When the sound changes, turn off the fill nozzle. Absolutely a great design. Upper right corner of the attached picture.

43189-ad6f7f0b9bb7046b5bfdf708dbf928cb.jpg


Ted
 
paulga said:
The bleeding instructions says the racor lid need to be open before the pump is turned on. So the pressure will not build up in the racor unit
Click to expand...
The fuel pump for priming the fuel system was an after production modification. A really piss poor design by a Jack leg.

Normally the pump is after the Racor separator so that the Racor acts as a filter for that pump. There is a small strainer screen in the bottom of that pump, but it doesn't protect the pump from water in the fuel.

Once fuel flows through the pump, it primes the engine pump and final filter (which are designed for pressure). To prime the engine system with your setup requires you to positive pressure the Racor. Would have been simple to install the pump after the lower "Y" valve before it goes to the engine.

Ted
 
O C Diver said:
The fuel pump for priming the fuel system was an after production modification. A really piss poor design by a Jack leg.

Normally the pump is after the Racor separator so that the Racor acts as a filter for that pump. There is a small strainer screen in the bottom of that pump, but it doesn't protect the pump from water in the fuel.

Once fuel flows through the pump, it primes the engine pump and final filter (which are designed for pressure). To prime the engine system with your setup requires you to positive pressure the Racor. Would have been simple to install the pump after the lower "Y" valve before it goes to the engine.

Ted
Click to expand...
To connect the facet pump after the lower 3 way valve - does it require adding one T before and one T after that 3 way valve?

Btw, the Ford Lehman 135 engine spin on fuel filters have a bleeding screw on top of each housing. User loosens the screws then use the manual lever on the lift pump to prime. When changing the racor filter only, I didn't have to prime the engine side.

IMG_20240720_104317.jpg
 
paulga said:
To connect the facet pump after the lower 3 way valve - does it require adding one T before and one T after that 3 way valve?

Btw, the Ford Lehman 135 engine spin on fuel filters have a bleeding screw on top of each housing. User loosens the screws then use the manual lever on the lift pump to prime. When changing the racor filter only, I didn't have to prime the engine side.

View attachment 156620
Click to expand...
I've seen people pull fuel through their primer pump. Believe that's what the Racor primer pump does if you add their kit. You could also insert two tees with a valve in between to bypass the primer pump.

If you want to bypass / eliminate the primer pump, fill the Racor to the rim with diesel, put the lid back on, and use the manual lever on the lift pump. It will accomplish the same thing. That's the way I always did it.

Ted
 
O C Diver said:
I've seen people pull fuel through their primer pump. Believe that's what the Racor primer pump does if you add their kit. You could also insert two tees with a valve in between to bypass the primer pump.

If you want to bypass / eliminate the primer pump, fill the Racor to the rim with diesel, put the lid back on, and use the manual lever on the lift pump. It will accomplish the same thing. That's the way I always did it.

Ted
Click to expand...
Does "two t with a valve in between" mean connecting two such diverters in series?
The middle spout in the two t together will by pass the pump


Screenshot_2024-07-20-18-59-26-17_40deb401b9ffe8e1df2f1cc5ba480b12.jpg
 
paulga said:
Does "two t with a valve in between" mean connecting two such diverters in series?
The middle spout in the two t together will by pass the pump


View attachment 156653
Click to expand...
Ok, time for some nomenclature. On a "T", the straight line across the top is called the "Run" as it's a straight line through the "T". The down leg is called the "Bull". Think of a male cow with his horns across the top.

While you can certainly do it with 2 "Y" valves, it's even simpler if you plumb to tees with the "Runs" in line with a connecting hose ( T T ). Then plump the pump to go out one Bull and back in the other Bull. Now in the hose between the two Runs, insert a valve.

To prime, close the valve and operate the primer pump. When priming is complete, open the valve. The fuel will take the path of least resistance through the two Runs. The pump also has valves that add resistance to the flow, making that path less desirable.

The above description is how your primer pump is currently plumbed.

Ted
 
O C Diver said:
Ok, time for some nomenclature. On a "T", the straight line across the top is called the "Run" as it's a straight line through the "T". The down leg is called the "Bull". Think of a male cow with his horns across the top.

While you can certainly do it with 2 "Y" valves, it's even simpler if you plumb to tees with the "Runs" in line with a connecting hose ( T T ). Then plump the pump to go out one Bull and back in the other Bull. Now in the hose between the two Runs, insert a valve.

To prime, close the valve and operate the primer pump. When priming is complete, open the valve. The fuel will take the path of least resistance through the two Runs. The pump also has valves that add resistance to the flow, making that path less desirable.

The above description is how your primer pump is currently plumbed.

Ted
Click to expand...
Thanks for the technical names. I was not find them from google

When the prime pump is running, it pushes diesel to the engine that is off. The fuel will push through the spin on filters, lift pump, oil cooler etc. then simply return to tank via the return line, right?

Btw, why is this T plus valve called a Y?
Screenshot_2024-07-20-18-59-26-17_40deb401b9ffe8e1df2f1cc5ba480b12.jpg
 
paulga said:
Thanks for the technical names. I was not find them from google

When the prime pump is running, it pushes diesel to the engine that is off. The fuel will push through the spin on filters, lift pump, oil cooler etc. then simply return to tank via the return line, right?

Btw, why is this T plus valve called a Y?View attachment 156656
Click to expand...
A long time ago in a far away land....

The original "Y" valve resembled a "Y", with the down leg either supplying the left or right upper branch. It doesn't take a master plumber to figure our that using a "T" in a congested panel is a more efficient use of space. The gas blending panel from my scuba business:

20191119_145657.jpg


Once the Y gave way to the T shape, it was easy to also incorporate "all closed" or "both" into the valve.

BTW, I didn't make the above panel, a Dupont master plumber, engineer, and very good friend, engineered it and built it for me.

Ted
 
O C Diver said:
A long time ago in a far away land....

The original "Y" valve resembled a "Y", with the down leg either supplying the left or right upper branch. It doesn't take a master plumber to figure our that using a "T" in a congested panel is a more efficient use of space. The gas blending panel from my scuba business:

View attachment 156666

Once the Y gave way to the T shape, it was easy to also incorporate "all closed" or "both" into the valve.

BTW, I didn't make the above panel, a Dupont master plumber, engineer, and very good friend, engineered it and built it for me.

Ted
Click to expand...
Thanks, I get where the Y is from. This plate looks so well organized. even I can kind of follow the flow in my mind.

my other question was, with the engine off, the prime pump keep pressurizing diesel to the engine. will the fuel be pushed through the spin on filters, lift pump, oil cooler etc. then simply return to the fuel tank via the return line? i don't know if this passage remains open when the engine is off.
 
paulga said:
my other question was, with the engine off, the prime pump keep pressurizing diesel to the engine. will the fuel be pushed through the spin on filters, lift pump, oil cooler etc. then simply return to the fuel tank via the return line? i don't know if this passage remains open when the engine is off.
Click to expand...
Yes. If you think about your lift pump manual lever, it allows you to suck fuel from the tank, through the plumbing, through the Racor separator, and to the lift pump. Then the pump pushes fuel through the final filter, through the injector pump, and finally the return line to the fuel tank. Basically the valves throughout your fuel system (from the fuel tank back to the tank) are check valves or one way valves, often spring loaded, allowing fuel to easily pass in one direction and then closing till the next pulse of fuel.

Ted
 
O C Diver said:
A long time ago in a far away land....

The original "Y" valve resembled a "Y", with the down leg either supplying the left or right upper branch. It doesn't take a master plumber to figure our that using a "T" in a congested panel is a more efficient use of space. The gas blending panel from my scuba business:

View attachment 156666

Once the Y gave way to the T shape, it was easy to also incorporate "all closed" or "both" into the valve.

BTW, I didn't make the above panel, a Dupont master plumber, engineer, and very good friend, engineered it and built it for me.

Ted
Click to expand...
Wow, apologies if I cause offence as its surely a masterpiece, but in my humble opinion a costly overengineered and unecessaraly complicated system. Every joint a potential leak and thats just on this panel alone.
 
Irish Rambler said:
Wow, apologies if I cause offence as its surely a masterpiece, but in my humble opinion a costly overengineered and unecessaraly complicated system. Every joint a potential leak and thats just on this panel alone.
Click to expand...
No offense taken.
You don't know what I did, so you wouldn't understand the required complexity.

Ted
 
O C Diver said:
No offense taken.
You don't know what I did, so you wouldn't understand the required complexity.

Ted
Click to expand...
Thanks Ted. I just have a simple pickup coming through a Caterpillar centrifrugal water separator/filter, lift pump, engine filter with button pump to save bleeding.
Enjoy your semi retirement buy keep posting, you've a lot to teach some of the young 'uns, and a few older guys who need guidance too !
 
O C Diver said:
I suppose grease would work for a pipe thread sealant in this application as there is zero pressure.

The manifold and elbows aren't aluminum which negates the need for dielectric sealant. Just make sure whatever sealant you use is diesel rated.

Ted
Click to expand...
I have some questions on the manifold

1. i have a manifold from mcmaster. It labels the inlets (two, 3/4" npt) on the two ends, and outlets (three, 1/2" npt) on one side. Can each inlet be used as an outlet, and each outlet be used as an inlet?

5975k35c1-c01f-digital-master1566217285-p9@2x_637017980660921575.png


2. the supply hose to the engine is 5/16", does it require the manifold outlets (if i add a manifold) and all the plumbing pieces need to be at least 5/16"?

Image_202407211138521.jpg


3. the material is anodized aluminum, the elbow/nipples that go into the outlets are brass. does it need dielectric grease on the female thread inside the outlet, if i'm going to use the yellow rector 5 on the elbow theads?
 

Attachments

  • 5975k35c1-c01f-digital-master1566217285-p9@2x_637017980660921575.png
    5975k35c1-c01f-digital-master1566217285-p9@2x_637017980660921575.png
    72.3 KB · Views: 12
paulga said:
I have some questions on the manifold

1. i have a manifold from mcmaster. It labels the inlets (two, 3/4" npt) on the two ends, and outlets (three, 1/2" npt) on one side. Can each inlet be used as an outlet, and each outlet be used as an inlet?

View attachment 156674

2. the supply hose to the engine is 5/16", does it require the manifold outlets (if i add a manifold) and all the plumbing pieces need to be at least 5/16"?

View attachment 156675

3. the material is anodized aluminum, the elbow/nipples that go into the outlets are brass. does it need dielectric grease on the female thread inside the outlet, if i'm going to use the yellow rector 5 on the elbow theads?
Click to expand...
1. Yes, each hole can be used as an inlet or outlet.

2. If you head off the beaten path a little, you will find on line, brass hose barbs to male pipe threads in all sorts of different configuration sizes. You will find 1/8" hose barb to 1/2" MPT. You will find 3/8" hose barb to 1/8" MPT. I'm sure you can find 5/16" hose bard to 1/2" MPT. If you're looking for 90 degree adapters, pickings aren't as plentiful.

3. I wouldn't bother on manifold fittings. It's unlikely that water will sit anywhere where brass and aluminum come together, based on flow rates and no open air space. A fuel tank has open air space and theoretically could be exposed to internal sweating. The cost and difficulty of replacing a fuel tank, takes my OCD to a different stratosphere.

Ted
 
O C Diver said:
1. Yes, each hole can be used as an inlet or outlet.

2. If you head off the beaten path a little, you will find on line, brass hose barbs to male pipe threads in all sorts of different configuration sizes. You will find 1/8" hose barb to 1/2" MPT. You will find 3/8" hose barb to 1/8" MPT. I'm sure you can find 5/16" hose bard to 1/2" MPT. If you're looking for 90 degree adapters, pickings aren't as plentiful.

3. I wouldn't bother on manifold fittings. It's unlikely that water will sit anywhere where brass and aluminum come together, based on flow rates and no open air space. A fuel tank has open air space and theoretically could be exposed to internal sweating. The cost and difficulty of replacing a fuel tank, takes my OCD to a different stratosphere.

Ted
Click to expand...

i found the three plumbing pieces online. now the questions are

1. 3/8" barb fits the hoses to the pump but is a bit larger for the 5/16" engine supply hose. is it good to fit the 5/16" hose onto a 3/8" barb?

2. how to mount these pieces to the bulkhead?


3/8“ T fitting x 2
Screenshot 2024-07-21 131001.png

3/8" hose Barb x 3/8" NPT x 2

71EOhIm0uPL._AC_SX679_PIbundle-2,TopRight,0,0_SH20_.jpg


3/8" ball valve
Screenshot 2024-07-15 231235.png
 
paulga said:
i found the three plumbing pieces online. now the questions are

1. 3/8" barb fits the hoses to the pump but is a bit larger for the 5/16" engine supply hose. is it good to fit the 5/16" hose onto a 3/8" barb?

2. how to mount these pieces to the bulkhead?


3/8“ T fitting x 2
View attachment 156676
3/8" hose Barb x 3/8" NPT x 2

View attachment 156677

3/8" ball valve
View attachment 156678
Click to expand...
This can adapt: Amazon.com
As can this: https://www.amazon.com/Joywayus-Red...ix=3/8+to+5/16+tee,industrial,130&sr=1-1&th=1

Mounting such items is a relatively trivial challenge that can be done many ways.
 
paulga said:
i found the three plumbing pieces online. now the questions are

1. 3/8" barb fits the hoses to the pump but is a bit larger for the 5/16" engine supply hose. is it good to fit the 5/16" hose onto a 3/8" barb?

2. how to mount these pieces to the bulkhead?


3/8“ T fitting x 2
View attachment 156676
3/8" hose Barb x 3/8" NPT x 2

View attachment 156677

3/8" ball valve
View attachment 156678
Click to expand...
5/16" hose needs to be on 5/16" hose barb. Buy a pipe thread tee and get the correct hose barb to pipe thread adapters. Alternatively check the fitting on the engine and replace it with 3/8" hose barb, and replace the fuel line.

Thought you had a manifold?

Ted
 
O C Diver said:
5/16" hose needs to be on 5/16" hose barb. Buy a pipe thread tee and get the correct hose barb to pipe thread adapters. Alternatively check the fitting on the engine and replace it with 3/8" hose barb, and replace the fuel line.

Thought you had a manifold?

Ted
Click to expand...
got it. I have seen a 4mm fuel hose is fit onto a 5mm or 6mm barb in a diesel heater installation. In my test, this is pretty easy to fit. Maybe this flexibility doesn't scale to larger hoses.

using just one manifold, without ball valve + T, is it possible to by pass the pump?
 
paulga said:
using just one manifold, without ball valve + T, is it possible to by pass the pump?
Click to expand...
No, if you setup a bypass for the priming pump without a valve or check valve on the other line, the fuel will likely travel in the loop you created and will likely not prime your fuel system.

Ted
 
O C Diver said:
No, if you setup a bypass for the priming pump without a valve or check valve on the other line, the fuel will likely travel in the loop you created and will likely not prime your fuel system.

Ted
Click to expand...
how do you use the manifold plus valve to do the by pass?

it's more cost effective to use those couplers in my post #50 without using a manifold
 
paulga said:
how do you use the manifold plus valve to do the by pass?

it's more cost effective to use those couplers in my post #50 without using a manifold
Click to expand...
It will require a manifold, a tee, and a valve. Come out of the manifold with the valve. Attach the tee Run to the valve. Come out of the manifold and go to the primer pump inlet. Tie the output of the primer pump to the Bull of the tee. The other end of the tee Run goes to the engine.

Why don't you just use a Y valve and a tee? The Y valve selects primer pump or bypass. The tee brings the 2 lines back together.

Ted
 
O C Diver said:
It will require a manifold, a tee, and a valve. Come out of the manifold with the valve. Attach the tee Run to the valve. Come out of the manifold and go to the primer pump inlet. Tie the output of the primer pump to the Bull of the tee. The other end of the tee Run goes to the engine.

Why don't you just use a Y valve and a tee? The Y valve selects primer pump or bypass. The tee brings the 2 lines back together.

Ted
Click to expand...

a Y and a T further simplifies it, great thanks!

this three way Y valve has two screw holes, so I can mount it on a plywood piece. are there T fitting with mounting holes? or can it be soldered or welded to a metal bracket?

61bP0SkrpdL._AC_SL1050_.jpg


Screenshot 2024-07-21 131001.png
 
paulga said:
a Y and a T further simplifies it, great thanks!

this three way Y valve has two screw holes, so I can mount it on a plywood piece. are there T fitting with mounting holes? or can it be soldered or welded to a metal bracket?

View attachment 156687

View attachment 156688
Click to expand...
Don't solder or weld anything to the tee.

The below pic shows electrical conduit PVC pipe clamps available at Home Depot and lowes. Sizes range from 1/2" pipe to 3" pipe. Assemble the hoses on the tee and then close to the tee, fasten the hoses to the bulkhead. You will see them in post #15 holding hoses to the bulkhead.

20240722_112938.jpg


Ted
 
O C Diver said:
Don't solder or weld anything to the tee.

The below pic shows electrical conduit PVC pipe clamps available at Home Depot and lowes. Sizes range from 1/2" pipe to 3" pipe. Assemble the hoses on the tee and then close to the tee, fasten the hoses to the bulkhead. You will see them in post #15 holding hoses to the bulkhead.

View attachment 156689

Ted
Click to expand...
got it, this will reduce the vibration.

I intend to put the Y and T at the lower left corner as shown below. or do you see any better arrangement?

Image_202407211138523.jpg
 

Attachments

  • Image_202407211138522.jpg
    Image_202407211138522.jpg
    162.7 KB · Views: 8
You must log in or register to reply here.

Similar threads

dhays
Cracks in coolant hose
2
Replies
49
Views
3K
Irish Rambler
Irish Rambler
C
Fuel Valve position question
Replies
2
Views
389
O C Diver
O C Diver
balder8
Flue system, high temp fuel shut up and overflow feature in Dickinson install
Replies
0
Views
434
balder8
balder8
M
1990 California 59’
Replies
0
Views
124
michaelgurvin
M
mncruiser
My boat plumbing sucks more than yours! Maybe.
Replies
11
Views
1K
mncruiser
mncruiser

Latest posts

Back
Top Bottom