In the process of replacing fuel lines, lift pump, and primary filter assembly. Planning to install a “Y” after the secondary filter with shut off valves on the two outlets so that I can connect one side to the engine and one to the return line to the tank for purging air after filter changes. Question: can I simply add a “T” in the return line or do I need to add a valve between the “T”and the engine? Don’t want to put modest pressure on the fuel thingies on the engine if that would be a bad thing.
Fuel flow question
- Thread starter Elrod
- Start date
Prairie Schooner
Jeff & Donna, E35-3 purchased 7/21
What kind of engine do you have? Our Universal M25 has a bleed valve which does exactly what you describe.
(You might consider adding some basic engine info to your signature line. I find it helps me get more targeted advice.)
Prairie Schooner
Jeff & Donna, E35-3 purchased 7/21
JSM
Sustaining Member
Put a new on on mu M25xp last year. Check Amazon under Kubota fuel bleed valve they can be had for as low as $12.00.
Pete the Cat
Sustaining Member
If you turn off the fuel at the tank before you open the system to change filters, you should not have to purge any air from any of the lines. Maybe i am not understanding your issue.
Hi Ray, I was initially concerned about back pressure on the fuel return line at the high pressure pump on the engine. The suggestion to just add a bleed valve and the in-between assembly seems like the route I will be taking.
Thanks for your interest, but not sure that I agree with you about not needing to purge air from lines. In my personal experience, it is virtually impossible to avoid some air in the system even when pre-filling the spin-on filters with fuel, perhaps you are more agile than me. (likely)
Thanks for your interest, but not sure that I agree with you about not needing to purge air from lines. In my personal experience, it is virtually impossible to avoid some air in the system even when pre-filling the spin-on filters with fuel, perhaps you are more agile than me. (likely)
Pete the Cat
Sustaining Member
Not sure I understand. The MX 25XP installation has an electric fuel pump that pumps at some fairly low PSI (7lb?) that has a hard time in some installations lifting column of fuel from a distant, lower tank if the fuel line is emptied back to the tank. But if the shutoff valve is closed before you open any of the system up, you can hold the incoming fuel column and it will immediately produce fuel for bleeding when starting. There may be a need for bleeding the system but the air will only be from the filter or the line between the lift pump and the injector pump. The pressure in the return line is low--I am not sure what you mean by "back pressure" there. Most Yanmars are self bleeding so this is doubly important with those engines as they can take some time and cranking of their mechanical lift pumps to pull the fuel column to the injector pump.
Ray,
I need to replace fuel lines (from pump to filter one, from filter one to filter two, filter two to engine, and between injectors) per recent insurance survey. One hose is not ABYC compliant, apparently (though installed by a pro four years ago), and others are showing signs of age. I’ve just begun to ponder the whole process.
Do I understand correctly that closing the fuel valve between my tank and fuel pump may allow me to proceed this winter with changing the lines, not being too concerned about air/fuel in the new lines until start-up in the spring when I can open the valve, activate the fuel pump, and use the bleed valve on the engine? This may be too naive a question at this point of my learning curve—feel free to say so.
Thanks,
Deborah
Pete the Cat
Sustaining Member
Short answer is yes there will be no problem over the winter and you should close the tank valve before starting to open anything on the fuel system--it will save you a lot of pumping in the Spring. You will have air to remove in the Spring from the lines you replace. If are talking about the fuel return line when you said "the line between the injectors" I am going to assume you are talking about the fuel return line to the tank; that line does not need to be bled. Yes you can bleed the system at the bleed valve. Fill the filters before installing them and it should not take too much running of the electric fuel pump to get the air out. If you have bled the system (no or few bubbles) and it still won't start, you might have to loosen the top of one of the injectors to see if you got air between the pump and the injector--but if you didn't open the lines between the injector pump and the injectors that should not be necessary. Do you have Nigel Calder's Boatowners Manual? Gives a good explanation of the process. There are Youtube videos on this. I really have come to hate surveyors. There is really nothing really special about CG labelled fuel line and a good surveyor should know that. But there are a lot of surveyors who have just read some books, some how passed a test, and look for a list of things to write up rather than actually assess the seaworthiness of a vessel.
Prairie Schooner
Jeff & Donna, E35-3 purchased 7/21
What you say is true, Ray. The other part of the picture is ABYC and insurance companies. Our surveyor explained to us that even though a non-marine component could be fine, if there's an insurance claim, payment could be denied if ABYC guidelines are not followed. So I end up doing an informal risk/benefit analysis whenever I contemplate the use of a non-marine part.