OBS to LQ4 Fuel system

[watdog]

So I am helping a relative with this conversion and have a couple fuel system questions that I can't exactly find the answers too.

The stock system was a return system. It has two rubber lines by the firewall into some metal lines. I need to know if these rubber lines will be able to hold the new amount of fuel pressure or not?

The new engine has two lines coming off it for the fuel system. Can I use a return system on this engine or do I need to convert it over to a returnless fuel system? If so what do most people do with the other fuel line.

Also what type of connector is this on the engine? I looked at the 2003 tahoe and it looks like it's a push on style that automatically locks on the fuel line.

If anyone has any links that is always appreciated also. Read the OBS to LS1 conversion sticky and still need some help. Thanks in advance.

[RedHeartbeat]

The single line is a 3/8" snap-loc fuel line that has an oring internal to the female connector. A dual line will have a 5/16" snap-loc connector. The fuel lines in non-vortec engine will only be safely rated for about 15 psi. What year truck is the OBS since the later models were setup for high pressure in the vortec engines.

[watdog]

The vehicle is a 94 suburban. The new engine is the 6.0L LQ4.

[RedHeartbeat]

If the LQ4 has a single feed fuel rail, do the conversion to a Corvette style fuel filter as mentioned in the conversion topic. The filter will supply a constant 58PSI to the fuel rail and the fuel pressure regulator on the fuel rail will give you 50 PSI at idle and 58 at WOT. Cut the lines at the stock fuel filter and splice the Corvette filter in there. The return line is also there. You will have two lines on the back side of the filter and one line from the filter going to the engine. All the parts required to make it work are available from most any auto parts store. Be sure you use hose rated for 60 PSI or more.

[watdog]

So the fuel line on the engine looks like it has both a supply (before the regulator) and then a return line (after the regulator). If I run both lines down to the corvette style fuel filter then I would connect them to the two sides of the fuel filter. The supply line would then run into the fuel filter inlet. So now I am confused at where I would connect the return line that goes back to the tank.

On the tahoe it looks like both lines come off the engine and then run to that style fuel filter. And then the supply from the fuel pump goes to the inlet on the fuel filter. Didn't see a return line for the tank. However, maybe it is down there.

PS thanks for your patience.

[RedHeartbeat]

Okay, if you have a supply and return line on the fuel rail then you can use both lines coming from and returning to the fuel tank, you will just have to alter the ends so that your connectors will lock onto the fuel rails. Did you install a high pressure pump in the fuel tank?

[hewlett2002000]

very good info

[Jgoodfella069]

So I was curious, if the OBS lines have been replaced with steel braided, don't know what PSI max though, they should be fine to run with a high pressure pump? Just convert the ends to match the quick connects on the rails? I'm doing a conversion right now and was needing to know the details of the Fuel system. Don't mean to butt in.

[RedHeartbeat]

Braided hose should be good to 300 psi if I remember correctly

[r6z4o6]

I used the factory braided lines from some undetermined year OBS and didn't have to cut any lines, spent less than $50.00.

800-078 + 800-058 = 3/8 line
800-079 + 800-057 = 5/16 line