Identifying fuel line from tank and return fuel line

On this 2007 1grfe prerunner, these 3 lines run together under the truck towards the fuel tank.

not sure what the line on the left and the filter like object on it is. Also can't tell which of the 2 lines on right is the fuel return line. Can anyone enlighten me on these 3 lines. Thx.

This pic is drivers side of engine.

 

The one with the canister is the EVAP purge line, the canister is just a pulse damper for the purge valve. Nothing more than a hollow can.

I believe the middle one is the fuel supply line and the rearmost one is the return line.

 

Thx! I was looking for a directional arrow to distinguish between the supply and return, but found nothing. Some thread said they are distinguished by the diameter of the line but both look same size to me.

 

Yea I just looked through my pictures, the middle one is the supply line (circled in blue) and the rear one is return.
What are you trying to check?

 

Thx for confirming. The truck has been throwing a P0171 and P0174 lean bank 1 and bank2 codes for a while. Mechanic said it was maf sensor. Replaced and same problem. Then said it was brake booster vacuum leak. Replaced and same problem.

But soon afterwards also saw a P0300, random multiple cylinder misfire in addition to the above 2 codes. Reading thru some threads I noticed this was similar problem people with fuel line issues were having. The truck has 235k miles on it and there is occasional random hesitation when pressing accelerator.

Long story short I plan to test the fuel pressure for any anomalies this weekend.

 

Ah yea you need to tee into the line, the easiest place is at the quick connect I have circled in blue on the pic above.

You will need a tee adapter like this or similar.

$31 BETOOLL Fuel Pressure Test Kit 0-100PSI with 9.497.896.30 Fuel Line Fittings

https://www.amazon.com/BETOOLL-Fuel-Pressure-0-100PSI-Fittings/dp/B07LF26ZTJ?th=1

 

Super! I ordered that yesterday with some hesitation as it came closest to any tool at a reasonable price. Though some did complain that the hoses on the units are not for fuel but water and air and that it deformed after a year of use. But those were mechanics using it with much greater frequency and I really need to test it now.

 

I have the "pro" kit like that, the hose has gotten hard but it hasn't broken yet. The gauge has died but I just replaced it with a different one.
If the hose does get bad I'll just cut the crimp sleeves off and put some fuel injection hose on it with hose clamps.

 

That's good to know. I ordered the "not" professional one. But at least when the time comes I can mod it. Thx for your advice. Will get me going in the right direction.

 

Yea I basically bought the "pro" kit for the adapter pieces, the hose and gauge aren't great but are sufficient for DIY.
I have a whole collection of different adapters and fittings I've collected over the years, comes in handy for checking fuel pressure and other stuff on various things.

 

The fuel pressure, using the above gauge is at 25 psi with engine on. It remains there after 5 mins, which implies there are no leaks. The manual says fuel pressure should be about 41 psi. So I guess it's a weak fuel pump that needs replacement.

 

That would match up with the symptoms you are having.

 

You were a great help. Thanks for sharing your insights.