fuel line return issue

[Autumns Wind]

I recently installed a new fuel tank with only 3 ports. Vent, fill, supply. Yet on my 30HP universal diesel, I have a fuel return line. So with out taping a hole in the tank. Can I 1 reroute the return to supply with a tee leading backk to fuel filter back to engine. 2 connect to vent with a check vale on return side. 3 cap line and abandon return line. Thanks Paul M

[Cheechako]

2, connect to vent is fine. Been there done that.

[HappyMdRSailor]

This has nothing but trouble written all over it....

You need the fuel circulating to keep it cool, clean it... AND not introduce CRAZY pressure in lines and components not designed to handle it....

Tap another hole in your tank...

[HappyMdRSailor]

Originally Posted by Cheechako

2, connect to vent is fine. Been there done that.

Vent tap I can see... capping the return, or re-routing it to the supply after the pickup... I can't...

[fishtrap]

I've T'eed return lines into vent lines and had no problems. The engine draws more fuel than it returns so the negative pressure in the tank pulls in the return fuel as well as air from the vent. I don't see any reason for a check valve. Obviously, if you have more than one tank you have to return to each tank via a valve and change return lines when you switch tanks. It's not recommended to return back to the feed line although some small engines are actually designed to do just that, go figure. The return is there for a reason, I wouldn't advise capping it.

[GILow]

Have a similar setup. Prefab tank with only a filler point, pickup pipe and breather.

Have been advised for my engine that the fuel return is critical to the longevity of the injectors (96 hp Nissan) so capping it would be an absolute no-no.

Our return is teed to the breather, but I needed to take care when replacing it that the breather line was a straight fall from the exterior vent to the tank so that return fuel could not pool in the line and effectively cause a mild airlock. This was first made evident when I was filling the tank one day only to have a small amount of fuel come out the breather into the cockpit. About 20 mls at most, but messy all the same. Once I straightened the line all has been good, and a lot less work in our case than drilling a new fitting would have entailed.

Matt

[Ziggy]

My return line is teed to the vent also. No problems. I don't see any need for a check valve.

[Autumns Wind]

Thanks guys. installing a tee in the vent, sounds like a plan.

[captain58sailin]

On my commercial fishing vessel it was tapped into the fill pipe about 12" below the cap, not a lot of pressure so it wouldn't cause problem with opening it while the engine was running.

[Roy M]

Ditto the fill pipe. Zero issues with flow or pressure, vent line remains clear. My vent line has the in-line overflow preventer.

[Pirate999]

Just a caution. If there is any back pressure, over time it will damage your injector pump. It's $800+ to repair. Personally, I'd do it right and put in a proper return. If you use your vent, make sure there are no blockages, ever.

[Blue Crab]

A modest thread drift. My PO (a diesel mechanic) mentioned he had changed tanks, and I wouldn't be able to fill the tank with the Yanmar 2GM running. I didn't think much of it, and the tank is in a tough spot to see what's what, but the thread on topping off underway got me to worrying. I cannot believe the PO would shortcut a critical mechanical system. Thoughts?