Fuel injection fuel line return fitting options

[mylesm260]

Re: Fuel injection fuel line return fitting options

To be completely honest, I'm not sure what the actual USCG regs are for fuel hose and EFI.

I know they all have to have some rating that is associated with strength and fire resistance (as in how many seconds can it be in flame before it burns through and bursts).

I chose hydrolic hose because I know it is many times better than whatever the USCG spec are in both those categories.

You're going to have to go and research it if you want to make sure you're USCG spec'ed.

It would be a shamed if it wasn't, because in my opinion, it's the safest way to go for sure, especially if you factor in the crimped fittings.


That's stuffed rated for 3000 PSI at stupid temperatures, I'm sure it's way stronger and way more heat/flame resistant than the minimum USCG requirements. It just may not be "pre-approved"

 

[JustJason]

Re: Fuel injection fuel line return fitting options

Type A1 to and from the tank will do just fine. On the engine itself should be all steel lines.

 

[mylesm260]

Re: Fuel injection fuel line return fitting options

*brainfart*


I've got the perfect solution right here, easy as pie.

Take out you're sender, and drill and tap it with a 1/8 NPT.

If you look at the picture of the sender you posted, it looks like they simply added a return fitting to a regular plane jane sender.

So long as there is enough "meat" on you're sender plate, I can't see why you couldn't just remove, drill, tap, reinstall and be done. Wouldn't even have to drain or clean out the tank after, or buy anything new.

 

[PRW]

Re: Fuel injection fuel line return fitting options

That very well may work! I still need a new sending unit either way. Mine is leaking like crazy from the center (not the gasket area)

 

[rodbolt]

Re: Fuel injection fuel line return fitting options

marine power makes an adapter to cut the return fuel line into the fuel fill line. I have used many.
I have also used the sender with a return line.
best bet is a vapor seperator type system and water cool it like 99% of the marinizers do, and eliminate the return fuel.
in years past you could get an MPI GM engine from marine power with either a water cooled returnless system or a return system that Teed into the fuel fill line.

 

[mylesm260]

Re: Fuel injection fuel line return fitting options

marine power makes an adapter to cut the return fuel line into the fuel fill line. I have used many.
I have also used the sender with a return line.
best bet is a vapor seperator type system and water cool it like 99% of the marinizers do, and eliminate the return fuel.
in years past you could get an MPI GM engine from marine power with either a water cooled returnless system or a return system that Teed into the fuel fill line.

IF you cool the fuel at some point, or the rail(s) themselves, I agree, you should be able to T you're return into you're main fuel line pre-pump.


The downside is you would loose you're fuel system's natural ability to push out any air bubbles (which can happen with low fuel and fuel swishing around in the tank)

having said all that, which is easier: adding the return, or adding cooling to you're fuel system?

especially since you're fixing you're sender ANYWAY, I would just add the proper return and be done with it.

 

[rodbolt]

Re: Fuel injection fuel line return fitting options

mylesm260.
thats why 99% of the EFI motors use a vapor seperator with or without a return to tank line.
when a returnless system is used the fuel MUST be cooled or at low speeds the pump and fuel will overheat and vapor lock,seen it personnaly.
on a fuel return type system what fuel isnt being consumed gets returned and cooled in the fuel tank.
most,not all, systems use a lift pump then a high pressure boost pump. most MPI systems typically run at 45 to 55 PSI.
fuel ,when compressed,gets very hot and if not cooled on the return will get even hotter the next time its compressed.
wanna see a fuel pump get really hot?
when the E fuels dissolve the paint from the inside of the fuel cell assy and the debris clogs the fuel pressure regulator screen and the rail pressures exceed 100 psi(my snapon guage assy only goes to 100 and the needle got pegged) the engine not only runs nasty rich but the pump overheats and wipes itself out if not caught and corrected soon.
goes back to routine maint and part of it is checking fuel rail pressures reguardless of customer complaints.

 

[180shabah]

Re: Fuel injection fuel line return fitting options

One more possible solution, with minimal "work". You can buy a fitting that allows you to tap into the 1 1/2" fuel fill line. Cut the fill line, clamp the "tee" inplace, hook up your return line and just let it "dump" back into the tank. It has been a while since I was looking, but I think I found these on Dennis Moore's ebay listings.

 

[PRW]

Re: Fuel injection fuel line return fitting options

I've thought about that but I haven't been able to find the proper hardware.

 

[rodbolt]

Re: Fuel injection fuel line return fitting options

all the marine power adapter was was a double ended 1 and 1 half inch brass hose barb with a 3 eighths hose barb brazed into it.
not very complex but it worked just like cars did for years.
its just that,especially for repowers, its easier to use a returnless system and a fuel cooler.
Yamaha does it,merc and volvo do it as well as many other marinizers.

 

[PRW]

Re: Fuel injection fuel line return fitting options

all the marine power adapter was was a double ended 1 and 1 half inch brass hose barb with a 3 eighths hose barb brazed into it.
not very complex but it worked just like cars did for years.
its just that,especially for repowers, its easier to use a returnless system and a fuel cooler.
Yamaha does it,merc and volvo do it as well as many other marinizers.

I scoured the Marine power website and wasn't able to find that adapter listed on the site

I did actually find all the parts I would need to setup the returnless and fuel cooler system. Unfortunately that would cost me several hundred dollars to get that into operation.
I think that the sending unit with the return line fitting incorporated into it is probably the most economical solution for me at this point. Plus it's probably the safest solution short of retrofitting the entire cooler/returnless system.

 

[Fishermark]

Re: Fuel injection fuel line return fitting options

I think that the sending unit with the return line fitting incorporated into it is probably the most economical solution for me at this point.

mylesm260 mentioned it earlier, and I would agree with him. The most economical and easiest way would be to modify your existing sender.

If you look at a closer picture of the link you posted, you will see exactly what they did:

I also note from the link that it specifically mentions it is for a diesel application. There may be no difference, but I would think it is a good idea to see what makes it specifically diesel. It may or may not work for your setup. Modifying what you currently have would be as simple as removing your sender, drilling and tapping, and then screwing in the appropriate sized fitting.

 

[mylesm260]

Re: Fuel injection fuel line return fitting options

You can buy a fitting that allows you to tap into the 1 1/2" fuel fill line.

Remember guys, his existing sender needs work, at the very least he needs to pull it. He may very likely need to replace it. He might as well run his return there.

I also note from the link that it specifically mentions it is for a diesel application. There may be no difference, but I would think it is a good idea to see what makes it specifically diesel.

I think it's just a mater of the vast majority of OEM EFI setups run returnless, and the aftermarket / automotive EFI systems run a return so they're not trying to market their product to gasoline efi people.

Where as the vast majority of diesel engines run a return to purge the air out of the fuel filter. Diesel engines run extremely high fuel pressure, and the high pressure pumps HATE air. So they're constantly "bleeding" the fuel filter back to the tank, to eliminate any air that ends up in the system.

That thing says for diesels, because for every 1 person out there that needs it for an aftermarket / automotive EFI system, there are 50 that need to replace their OEM diesel sender that had a return from the factory.

 

[rodbolt]

Re: Fuel injection fuel line return fitting options

gotta disagree with mylem260 again.
many modern electronicly controled diesiels run returnless systems.
the fuel return on a return style system had NOTHING to do with air pruging and everything to do with maintaining a specific PSI in the rail and keeping the unused fuel cool.
you are right on the dislike of air,some diesel rigs are a pain to reprime if the system is airbound.
on a gas EFI marine engine you have 3 choices,return the unused fuel from the rail to the tank for cooling.
use a vapor seperator that is water cooled or has a cooling device.
or idle for about 20 minutes and watch the engine shut down due to vapor lock and the pump and rail are so hot you cant touch them,I have seen that one .
as to why the above fitting is only diesel rated,liability and a lack of a UL rating for gasoline vapors.
same as the old walbro pumps that Grady white used for years as a fuel system primer.
liability made the pumps unrated for gasoline but still rated for diesel.

lets take the average mercruiser 8.1LHO.
takes about 28 gallons per hour at WOT but we still have to have about 45PSI on the fuel rail.
now we gotta idle in the stupid no wake zone.
now we still have to maintain 45PSI on the rail but our fuel consumption just dropped to about 1.3 GPH.
now we have a few choices,monitor rail pressure and fuel consumption and alter the pump operating voltage,rather complex but doable.
or regulate the rail pressure with a fuel pressure regulator and let the pump simply run at its max and the heated compressed unused fuel gets returned either to a vapor seperator thats water cooled or return this fuel back to the fuel tank for cooling.
as most marinizers have no clue who built the fuel cell or arranged the lines or even built the hull most opted for an engine mounted fuel cooler and vapor seperator.
thats why boats have them and automobiles dont, well that and most autos dont spend a lot of time in the water.
back in the mid 2000?s Marine Power offered a 300 HP mPI 5.7L with either a G Force vapor seperator that was water cooled from the seawater pump or you could opt to return the fuel via a tap in the fuel tanks fill line.
failure to do one or the other and the engine would idle about 20 minutes and shut down due to fuel boiling in the vapor seperator.
wanna see an engine,either diesel or gas EFI,run nasty and shut off? pinch off the rail return line.

trust me, I sold many of these and installed a few.

 

[mylesm260]

Re: Fuel injection fuel line return fitting options

gotta disagree with mylem260 again.
many modern electronicly controled diesiels run returnless systems.
the fuel return on a return style system had NOTHING to do with air pruging and everything to do with maintaining a specific PSI in the rail and keeping the unused fuel cool.

The return in a diesel has EVERYTHING to do with purging air.

Okay, we've established that the high pressure diesel pumps hate air. Look at this picture. Note how the low pressure diesel flows THROUGH the high pressure pump? This is to bleed out any air bubbles in the system. If there was no return, there would be nowhere for the air to go.


I drove commercial crane trucks for many years, some with a return, some without.

If you run out of fuel on the trucks with a return, you can simply add fuel to the tank, cycle the pump a few times and re-start the engine.

On trucks WITHOUT the return, even if you turned a corner with very little fuel left in the tank, you would get air in the filter, and the ONLY way to restart the engine would be to add fuel to the main tank and REMOVE the fuel filter and manually prime it. (most trucks had a manual prime button next to the fuel filter, but you would still have to unthread the fuel filter most of the way to brake the seal to allow the fuel to displace the air in the system.

Also, you're confusing different types of diesel engines. When you say RAIL, you are referring to a Common Rail Diesel. This is a relatively new technology that I believe isn't used in very many marine applications yet.


Older diesel engines will not have a "rail." They will have a high pressure pump with one output for each cylinder.


My tow rig is actually a Jeep liberty CRD.


Now we've verged way off topic.

Bottom line:
His existing fuel system is likely NOT going to work returnless.
He needs to fix/replace his sender

it seams pretty obvious what his best course of action is.

 

[PRW]

Re: Fuel injection fuel line return fitting options

Bottom line:
His existing fuel system is likely NOT going to work returnless.
He needs to fix/replace his sender

it seams pretty obvious what his best course of action is.

That is the bottom line. I'm going to go ahead and use the Moeller sending unit with the fitting already in place. Someone mentioned that it's actually a diesel specific part... it's not as you can see in the product description on their website.


http://www.moellermarine.com/aftermarket/fuel_systems/fuel_senders/

 

[windsors03cobra]

Re: Fuel injection fuel line return fitting options

Wow I figured that sending unit was the way to go when the OP posted it in like the 3rd post.
I would add you should put some kind of downpipe on that sender you dont want that returned fuel spraying all over in there like that, it'll foam, fume, mess and all other junk, tap the brass fitting for whatever size pipe you've decided will work.

 

[mylesm260]

Re: Fuel injection fuel line return fitting options

You know...


I had the same thought process when I first added my return, and it turns out that just dumping it back into the tank at the top and letting it fall down to the fuel level is just standard operating procedure. Many oem's do it that way.


My thought process at the time was along the line of yours. The tank is vented. If you have fuel falling down to the fuel level, you would think the turbulence would create fumes which would be lost out the vent in the form of hydrocarbon emission.

Either way though, there are plenty of setups out there that work that way

 

[PRW]

Re: Fuel injection fuel line return fitting options

Wanted to follow up on this..

I went ahead and bought the sending unit with the return line fitting. Everything is installed and the mess of hoses has been cleaned up. So far it works perfectly, no issues at all.