Gas Line

HPLou

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2 x Mercruiser 4.3LX
I will be installing 2 Fuel Water Separator because I have none installed at the moment.
My installation require to install 90 degree connector on the Gas Line.
Is it OK ?
Will it cause Flow Restriction in the hose ?
HPLou
 
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Grub54891

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Nope as long as it's sized right for the line.
 
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alldodge

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2 x Mercruiser 4.3LX
I will be installing 2 Fuel Water Separator because I have none installed at the moment.
My installation require to install 90 degree connector on the Gaz Line.
Is it OK ?
Will it cause Flow Restriction in the hose ?
HPLou

+1 agree with grub, and will ask a question; my guess is you do have filters right, and are they part of the fuel pumps?
 

HPLou

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No AllDodge I do not have Fuel Water Separator installed on both of my engines.
I've bought the kits and the location were I want to install them require a 90 degree fitting at the Outlet to get strait to the Fuel Pump.
 

alldodge

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Gee no fuel filters at all on the boat, go figure
 

HPLou

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Fuel Filter/Water Separator Question

I am following up on my Fuel\Water new installation Kit.
Resume;
I have Twin Merc 4.3LX 1989 and no Fuel\Water Filter installed.
I bought 2 Fuel\Water Kits SeaSense # 50052113, one for each engine.
I have filled both filter with fuel. I was able to start both engines. After approx 30 secs both engine stalls. When I remove the filters both are empty 2\3.
I fill them of fuel again and same happens, they empty 2\3 and both engines stalls again. The filters are installed about 1 feet over the Fuel Pumps on the engines.
I am thinking that the fuel from the Fuel Tank does not go throught the filters.
I have carefully followed the Arrows on the Fuel Bracket for the installation. Without The Water FilterKits installed, both engines works perfectly.
The fuel lines have 3\8'' ID. I have not modified the fuel lines lenght. I have only cut the Rubber Fuel Lines and add the Bracket.
Do I have the right Fuel Water Kits for my engines?
I read all the replies from my original message and the installation location does not matter, so I guess my install is OK.
Any body can help me please ?
 

carrier82

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To me it sounds odd that a filter could be added anywhere. Perhaps anywhere between the tank and the pump, but above the pump? To me that sounds like asking for trouble as the pump would have to do extra work. If you remove the fuel filters from their brackets (still attached to the fuel lines) and test them below fuel pump level, my guess is it would have a better chance of working. After googling the fuel filters you use, I think they should be okay for your application.
 

alldodge

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HPLou your last post is messed up somehow, not your issue hope the web kolks can fix. You posted

I am following up on my Fuel\Water new installation Kit.
Resume;
I have Twin Merc 4.3LX 1989 and no Fuel\Water Filter installed.
I bought 2 Fuel\Water Kits SeaSense # 50052113, one for each engine.
I have filled both filter with fuel. I was able to start both engines. After approx 30 secs both engine stalls. When I remove the filters both are empty 2\3.
I fill them of fuel again and same happens, they empty 2\3 and both engines stalls again. The filters are installed about 1 feet over the Fuel Pumps on the engines.
I am thinking that the fuel from the Fuel Tank does not go throught the filters.
I have carefully followed the Arrows on the Fuel Bracket for the installation. Without The Water FilterKits installed, both engines works perfectly.
The fuel lines have 3\8'' ID. I have not modified the fuel lines lenght. I have only cut the Rubber Fuel Lines and add the Bracket.
Do I have the right Fuel Water Kits for my engines?
I read all the replies from my original message and the installation location does not matter, so I guess my install is OK.
Any body can help me please ?

Since you have an 89 4.3 your fuel pump will have the filter above the pump as in the pic below
11 fuel pump.jpg

You don't want to have both filters installed. Also check your anti-siphon valve on the tank
 

UncleWillie

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...my guess is you do have filters right, and are they part of the fuel pumps?
I do not have Fuel Water Separator installed.
Gee no fuel filters at all on the boat...

"What we have here, is Failure to communicate."

There are Fuel Filters, and then there are Water Separating Fuel Filters.
Don't confuse the two! The OP may be adding Water Separating Filters,
but that does not mean there are not Fuel Filters already part of the Fuel Pump that he may not be aware of.
Pumping unfiltered gas straight from the tank into the carburetor is just asking for trouble.

To me it sounds odd that a filter could be added anywhere. Perhaps anywhere between the tank and the pump, but above the pump? To me that sounds like asking for trouble as the pump would have to do extra work.

Once the fuel lines have been primed, and as long as you do not try to suck gas up more than ~40 feet;
The only thing that matters is the difference in the height of the two end of the fuel line.
The pump only works as hard as the difference between the pump inlet and the Top of the fuel level in the tank.
The path the fuel hose takes in getting to the pump has no effect on the pressure/suction at either end. Think "Siphon".

If the filter is located above both the tank and the fuel pump. Changing the filter will not involve a minor fuel spill every time.
Once you remove the filter, any fuel in the lines will tend to run away from the open lines instead of toward them.
 

Texasmark

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Where I went to school any fitting is a restriction and interferes with the unrestricted flow of a liquid and can change laminar flow to turbulent which further restricts movement. Most fittings, QDs, and valves reduce the diameter of the conveyor and full flow is not maintained. Most systems are analyzed using the Reynolds graph and subsequent numbers of the system vs a straight pipe. Question is, what is the capability and what is the requirement? Usually testing of that system is required for the correct answer. So do what you need to do then take her out and test her at WOT loaded. If she passes you're good to go. If not time for Plan B.
 

carrier82

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UncleWillie, yes what i was referring to is the priming phase. I would imagine changing the filter would introduce air in the system, even when pre filled with fuel. I was told earlier that electric fuel pumps are self priming but tuhat can't be true on all occasions.
 

HPLou

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Thank you for the replies.
All I want do to is add a Fuel Water Separator on each fuel lines cumming from the same Fuel Tank. I have none installed.
I am not taking about Fuel Filters at Fuel Pump.
I want to prevent Water in Fuel Tank (if there his) to go throught the Fuel Lines.
And when added (new installation) , the engines stalls after 30 seconds. The Fuel from the Tank does not reach the Water Fuel Separator because after engine stalls , there is only 1\3 of Fuel in it.
Alldodge, thanks for the diagram. My installation is fine, I have followed the arrows.
 

dingbat

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Where I went to school any fitting is a restriction and interferes with the unrestricted flow of a liquid and can change laminar flow to turbulent which further restricts movement. Most fittings, QDs, and valves reduce the diameter of the conveyor and full flow is not maintained. Most systems are analyzed using the Reynolds graph and subsequent numbers of the system vs a straight pipe. Question is, what is the capability and what is the requirement? Usually testing of that system is required for the correct answer. So do what you need to do then take her out and test her at WOT loaded. If she passes you're good to go. If not time for Plan B.

Ding,ding, ding....correct
 

dingbat

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Thank you for the replies.
All I want do to is add a Fuel Water Separator on each fuel lines cumming from the same Fuel Tank. I have none installed.
I am not taking about Fuel Filters at Fuel Pump.
I want to prevent Water in Fuel Tank (if there his) to go throught the Fuel Lines.
And when added (new installation) , the engines stalls after 30 seconds. The Fuel from the Tank does not reach the Water Fuel Separator because after engine stalls , there is only 1\3 of Fuel in it.
Alldodge, thanks for the diagram. My installation is fine, I have followed the arrows.
Your vacuum locked. You have to "prime" the filters. Take them off, fill with fuel then re-install. Problem solved
 

alldodge

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Thank you for the replies.
All I want do to is add a Fuel Water Separator on each fuel lines cumming from the same Fuel Tank. I have none installed.
I am not taking about Fuel Filters at Fuel Pump.
I want to prevent Water in Fuel Tank (if there his) to go throught the Fuel Lines.
And when added (new installation) , the engines stalls after 30 seconds. The Fuel from the Tank does not reach the Water Fuel Separator because after engine stalls , there is only 1\3 of Fuel in it.
Alldodge, thanks for the diagram. My installation is fine, I have followed the arrows.

As uncle mentioned, any fuel pump should have no issue with pulling fuel from the tank and through the filter if there is no restriction, the pump is not weak and the lift is not to high. Your sucking fuel from the primed filter but your not bringing it up from the tank. I'm guessing you have a mechanical fuel pump
 

UncleWillie

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Any fuel pump is going to be self priming. They are positive displacement pumps, Not impeller pumps.
I have a 6hp OB that pulls fuel from a tank sitting on the ground with the engine in a barrel.
It has to lift fuel 4 feet, at idle, and has no trouble doing it.

Lets not confuse restriction with blockage.
He has a 4.3 with 3/8 fuel lines. He could add six 90 deg fittings and 12 feet of fuel line and still not have a problem.
He is running out of gas in 30 seconds at idle.

As AllDodge mentioned, "You're sucking fuel from the Primed Filter but your not bringing it up from the tank."
The problem is between the Filter and the tank. A minor air leak will kill it.
And it will be leaking Air In and not Fuel Out. Nothing to see!
Check that the hoses are all secure.

Just checking the obvious...
Your filter has 4 ports on it.
ALL 4 ports need to have something in them; either a hose or a plug.
If an unused port is open, it will suck air.
The Filter Cap pictured in Post #8 does Not have a fitting in the Upper Right Input Port!
 

carrier82

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You will prime the OB with the primer pump before operation so the comparation does not apply. In this case OP may not have a primer pump in his system. In case there is some air in the system, the mass of air is a lot less than that of the fuel so at priming the system the pump has to generate enough vacuum to suck the fluid to its highest point. I doubt your pump can pump 4 feet without priming.
 

carrier82

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Although I don't completely deny it, as the positive displacement pump type is unknown to me. But at least theoretically it would be harder to make a pump that would pump both gas and fluid equally well. My OB doesn't work unprimed (well, haven't tried if it could start without being primed, but at least it would take time).
 

carrier82

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What I'm trying to say here, is that when the fuel flows vertically upwards and air goes downwards, the hydrostatic pressure of the fluid will build up as long as it has to travel vertically. When there is air flowing downwards from the filter, the mass of the air doesn't help to build hydrostatic pressure downwards to the pump. That's why, at least to my knowledge, the priming phase would require the pump to be able to generate enough vacuum to overcome the hydrostatic pressure of the fuel at it's highest point. There must be some limitation on how much vacuum the pumps can generate. Or did I at sleep at the physics class?
 

dingbat

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Although I don't completely deny it, as the positive displacement pump type is unknown to me. But at least theoretically it would be harder to make a pump that would pump both gas and fluid equally well. My OB doesn't work unprimed (well, haven't tried if it could start without being primed, but at least it would take time).
Positive displacement pumps have an expanding cavity on the suction side and a decreasing cavity on the discharge side. Liquid flows into the pumps as the cavity on the suction side expands and the liquid flows out of the discharge as the cavity collapses because of their low compressibility. A pump's efficiency drops to near zero when trying to pump a compressible media like air.
 
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