Hi fellow Ford friends. I'm having some issues with my pickup and am out of ideas on what's wrong with it and was hoping someone here might have a good idea. I drive a 96 f150 with the 302 and it has a little over 240k miles. The truck is running very lean right now. It's getting too much air and not enough gas. If I go above 2 RPMs it sounds awful and won't really go as high as 4. I took it to a mechanic and they said maf sensor so I changed that and it didn't fix it at all. Its got a clean new k&n. New fuel filter, no change. The o2 sensor isn't that old either. The sensor at autozone recommended a $2 part (pcv valve I think is what it was) and that didn't fix anything. If anyone has a good idea what my next step should be, please let me know. Thanks guys!!

 

Low Fuel pressure is my first thought, clogged cat a second. Your truck should have 3 O2 sensors too, one each side upstream and one after the cat.

 

Find a new mechanic that knows how to diagnose the codes stored in your computer.

How do you know she's running lean ?

 

The scanner at O'Reilly gave me a code that read P0174 and said that the bank 2 system ran too lean. So that's how I'm figuring it's running too lean, although I don't really know what the bank 2 system is tho

 

Ok thanks, I know when I replaced an 02 sensor I only replaced one, so you think that could be the main culprit here?

 

possibly, when an O2 fails, it puts out a low voltage, or none, which is interpreted as a Lean condition.
did you replace the one on the drivers side ?

have you cleaned your MAF (Mass Air Flow) Sensor ?

 

I actually have a brand new sensor, so it's definitely clean. I haven't tried replacing additional 02s yet, so I'm thinking that would probably be the next thing to do. I'll have to crawl under and look to remember which one I have changed

 

No next thing you should do is pull codes and check fuel pressure. If you don't have a code reader then now is the time to get online and order a bluetooth OBD2 module to use with your phone, with your truck you can not only see and clear codes with it you can also see realtime data which can be really helpful when diagnosing problems.

 

Have you changed the fuel filter with 240kmi on it, you need fuel pressure gauge, to check fuel pressure, at the least it needs to be 30-32psi at idle, and when you remove vacuum line from the fuel pressure regulator, it should go/jump up to 38-40psi depending on how low it reads at idle, then if that checks out ok, need a longer hose to be seen while your driving and someone watch gauge while you drive, I've zip-tyed mine to windshield wiper and had friend watch while I drove, and write down what he see's so he dont have to remember, is safest way

 

So I was just under the truck looking at things and i'm 90% sure the 02 I replaced was on the driver's side. I found another one right by the catalytic converter. Ive been looking for oen here on the passenger side and it's kinda tricky to find. Just curious, it's there a way to test the 02s?

 

I did change the filter, that was a cheap easy thing to do plus it was due for a change anyway. Didn't change anything unfortunately. I'm learning towards an 02 senator right now but hoping I can find a way to test that before I sink any more money into this

 

Need to check fuel pressure

 

depending on your OBD 2 scan tool, it can check o2 sensor for you, you really need to see what fuel pressure does while idling, and under load, but maybe this link will help you check o2 sensor
www.obdadvisor.com/test-o2-sensor-with-scanner/

 

https://troubleshootmyvehicle.com/fo...-flow-sensor-1

 

I finally checked the fuel pressure. It read right at 30, so with how it's running I don't think that's the problem. I'm trying to figure out where to go next, stil thinking it's possibly an 02 sensor