Height our Racor 110A and Tank Bottom.

[DinoKanuck]

Question on ....Height of Racor vs Tank Bottom.
Any issue with putting a Racor 110A 10” above the bottom of a diesel tank?
This puts the top of the Racor 110: 1” below the 113 liter mark ( tank capacity) but 1” above the 90 liter mark and 5” above the 40 liter mark? I need a shut between the Racor and the tank. But any other considerations on what I propose or why I have the problem? (See below)
Reason for question…
I’ve been finding air in my Racor 200FG since buying the LM28 with a VP 2003 in 2013 and was blaming it on old copper fuel lines but I changed those and found air again.
A professional mechanic said the Racor needs to be lowered. The old 200FG was 23” above the bottom of the tank and 18” above the height of the fuel when I ran into a serious air-in-the-Racor problem last week. Because the 200GF has a plastic bowl and lowing a Racor requires going closer to the mixing elbow and rubber exhaust hose I am switching too a metal bowl Racor 110A and replacing 28” of aged exhaust hose.
Dino Kubik
LM28 with a happy and much quieter than a Yammer" VP 2003 with 2000 hours.

 

[Gunni]

Dino;
My Racor 110 is located well above my fuel tank. Perhaps 4-5" from the bottom of the filter body to the tank top. The remote fuel shut off valve is located at the fuel pickup connection. The fuel comes up to the filter body and down to the engine fuel pump. The filter is the highest point on my engine. No problems.

 

[jibes138]

My engine installation manual requires the fuel return line to run below the bottom of the tank then back up to the fuel return fitting. You may have a siphon since the fuel pickup is lower than the return line fitting. If the mechanical fuel pump is weak and allows fuel to back feed it might drain the line back to the filter until air in the filter stops the siphon. Do you also have an electric fuel pump in the fuel system?

 

[Lee Hadjiosif]

The filter will work at any height on the supply line, however, they usually place it on the lowest point on the hose to allow for air bleeding when you drain the filter.

 

[DinoKanuck]

My engine installation manual requires the fuel return line to run below the bottom of the tank then back up to the fuel return fitting. You may have a siphon since the fuel pickup is lower than the return line fitting. If the mechanical fuel pump is weak and allows fuel to back feed it might drain the line back to the filter until air in the filter stops the siphon. Do you also have an electric fuel pump in the fuel system?

Jibes 138... my return line comes up off the engine and crossed over the top of the Racor then down to the tank.

Are you suggesting the return line drop to the bottom of the hull then up to the return fitting on the tank? I can take it off the engine and route it always lower than the feed line and then up to the return fitting.

Only have the engine's lift pump. No electric pump

Dino

 

[DinoKanuck]

The filter will work at any height on the supply line, however, they usually place it on the lowest point on the hose to allow for air bleeding when you drain the filter.

Lee, I had the Racor 200FG at the highest point in the feeding system. Bad idea I guess.

 

[jibes138]

Jibes 138... my return line comes up off the engine and crossed over the top of the Racor then down to the tank.

Are you suggesting the return line drop to the bottom of the hull then up to the return fitting on the tank? I can take it off the engine and route it always lower than the feed line and then up to the return fitting.

Only have the engine's lift pump. No electric pump

Dino

. A siphon happens when the pressure head in one side of a hose is greater than the other side. Your pickup tube is almost at the bottom of the tank and you return is at the top of the tank. If the pump allows fuel to leak through it when the engine isn't running the fuel might siphon back to the tank resulting in air in your line and filter until the air breaks the siphon the way a vented loop does. If the return line loops down below the tank the pressure head on the loop will be greater than the pickup tube section preventing a siphon. This is my interpretation of the intent in my owners manual for the engine.

 

[DinoKanuck]

I can easily follow this approach to avoid a siphon situation.