I have a 97 f250hd with a 7.5 that is running rich ,new o2 sensor , no vaccum leaks . Any help would be appreciated

 

How do you know it's running rich?

 

What codes does it have? Is that truck OBD I or OBD II? could be either in that year. One possibilty is a stuck fuel pressure regulator, so check fuel pressure.

 

You can smell it's running rich. It is an obd 1 system . had it hooked up to a snap on scanner and it is showing that the egr isn't opening also , checked the fuel pressure and it's good . there is no vaccum at the egr but there is at the solenoid. also replaced the coolant temp sensor going to try replacing the intake air sensor

 

EGR really doesn't have anything to do with running rich. What codes did you get with the scanner? What are the fuel trim numbers?

 

the codes were 171,173,332,334 . don't know the fuel trim numbers off hand , heading to the garage now to work on it . I will take the laptop with me and post the numbers , Thanks

 

Did you remove the vacuum line at the Fuel Pressure Regulator to inspect it for signs of fuel by sight or smell? A ruptured FPR diaphragm is very common.

Why blindly replace sensors if there is no code for them?

 

Measure the EVP sensor output with a meter with the engine off, key on. Do the same with the engine running. Apply vacuum to the EGR, verify the EVP signal increases.

EVP= EGR Valve Position sensor, it sits on top of the EGR valve.

 

Check the evap solenoid see if its stuck open, that will cause a vacuum leak.

 

Are you referring to the Canister Purge (CANP) solenoid? If so, your theory is wrong. When that solenoid opens it routes the gas fumes to the input side of the throttle body.



Perhaps you meant EGR Valve Regulator (EVR)?


For reference: Fuel Injection Technical Library » EGR Vacuum Regulator (EVR)

 

No, That not what I'm talking about.
This is


When it fails in the open position you have a 1/4 vacuum leak

 

I disagree. The CANP routes the fuel tank vapors to the atmosphere side of the throttlebody.

 

That CX1100 connects to manifold vacuum, when it's open at a idle you have a vacuum leak, the O2's go lean, fuel trim is off. I'm pretty sure it's meant to open only at cruise. I had a Ranger a couple weeks ago that the fuel trims were way off, poor idle, at a idle that solenoid was open, the new one isn't, that fixed it.
That solenoid is used on most Fords from the mid 80's to about 97, probably all OBD1 vehicles.

 

I am more familiar with the 5.0/5.8L engines the CANP is connected to the throttlebody. I will check my manuals to see how the 7.5L is plumbed.

 

I just looked in Mitchell, 5.0, 5.8, and 7.5 49-States are all plumbed the same way, looks like the same diagram, you better look at it.