Bad fuel consumption

[Jody Breeze]

hello. I have 96 explorer 4.0 OHV 4X4. Why does it seem like im burning more fuel in idle than when I actually drive it? I have changed 02 sensors, plugs and wires, coil pack, cleaned maf sensor, installed new IAC and EGR valve, solenoid and dpfe. Checked fuel pressure it's reading 30psi. New fuel filter. No exhaust leaks. Cleaned fuel regulator. I am getting a 171 and 174 lean codes which I'm thinking is manifold gasket. Could this be the culprit?

 

[C420sailor]

What makes it seem that way?

Lean codes can absolutely be caused by a manifold gasket. Could also be caused by a vacuum leak elsewhere…cracked/broken vacuum hoses/evap lines, etc

 

[Jody Breeze]

well for example I can drive maybe 30 miles and burn maybe an 8th of a tank but just idling earlier for 5 or 6 minutes my gas gauge moved another 8th. I have checked under hood for vacuum leaks until I'm blue in the face and only found intake manifold with small leak but as engine heats up it tends to go away but I still hear a loud hiss or sucking noise and sure that's a problem but can't find it. Now that you mention evap leak I do have a evap inc. On my obd2 scanner when I check for codes under the IM readiness. Basically I'm getting 171 174 under codes and under freeze frame my stft( short term fuel trim) is in the positive 20s and ltft(long term fuel trim) is in the positive 20s but have seen them both in the 30s and under IM readiness it shows evap inc and cat monitor inc when I got this truck last year it had 15 codes so I have come a long way but this fuel consumption in idle only has got me puzzled.

 

[C420sailor]

Gotta find the hiss. If it’s audible, I’m betting on a hose or cracked line somewhere…that’s a big leak.

1/8 tank in even 10 mins is about 13 gallons per hour. My bet on that is an erroneous fuel level indication. You’d snuff the motor out spraying that much fuel into it at idle, if the injectors would even flow that much.

Find the air leak and we’ll go from there

 

[Jody Breeze]

Gotta find the hiss. If it’s audible, I’m betting on a hose or cracked line somewhere…that’s a big leak.

1/8 tank in even 10 mins is about 13 gallons per hour. My bet on that is an erroneous fuel level indication. You’d snuff the motor out spraying that much fuel into it at idle, if the injectors would even flow that much.

Find the air leak and we’ll go from the

10-4. I will do some in depth searching again tomorrow hopefully I can find something because I can hear it with the hood closed. That bad it should not be a problem but so many places to check. I will let you know what I come up with. Thank you for your response and time. I appreciate it.