So, I was throwing 5 codes prior to today, the same 2 lean codes, air pump, purge valve and cyl 1 misfire.

Today i changed out most of the vacuum lines, put the proper belt on so the air pump is working again *PO has a smaller belt on it* did an oil change and trans fluid/filter change...

Truck cranks a little faster, shifts smoother but runs like crap! Took it to oreillys to check the codes and all of them are gone except lean bank 1 and bank 2.

surely changing vacuum lines out didnt cause it to run bad, is it the air pump?

Also, sprayed everything with carb cleaner, cant find the vacuum leak that i thought was causing the lean code.

So, air pump causing the running rough? I need it to pass inspection.

96 f150 2wd auto 4.9

 

Start by checking your fuel pressure with the engine running, and verify the fuel pressure increases as you increase throttle.

Next I'd think about replacing your O2 sensors, but both banks reading lean at the same time indicates the issue is likely elsewhere.

 

Thanks for the reply.

I just find it odd, it ran fine before, changed some vacuum lines with new ones, and put the OEM size belt back on for the air pump and now it runs like crap. But got rid of 3 out of 5 error codes at the same time.

 

anyone else?

 

Post back with your results

 

Hello Jim, i just went through the same thing with my 96,4.9,found the front fuel pump was weak ,it showed up with a hard draw in fuel,could switch to rear tank and it all cleared up...joe