Running lean code
Thread Starter
|
New User
Joined: Sep 2021
Posts: 15
Likes: 1
Running lean code
I have running lean code on 1994 Ford F-150 5.0l engine. List of new parts or replace: brake booster, fuel pressure regulator, vacuum lines in engine, check valves on secondary air injection system. Egr, vacuum solenoid's and all exhaust is tight. I'm not sure what else is there.
Cargo Master
Joined: Nov 2009
Posts: 2,190
Likes: 620
Check for vacuum leaks in the intake path. Between the throttle body and the heads. (i.e. Between the throttle body and plenum, between the upper plenum and lower manifold, between the manifold and heads, the EGR and IAC Gaskets, etc.)
Lead Driver
Joined: Jun 2021
Posts: 5,221
Likes: 805
I have running lean code on 1994 Ford F-150 5.0l engine. List of new parts or replace: brake booster, fuel pressure regulator, vacuum lines in engine, check valves on secondary air injection system. Egr, vacuum solenoid's and all exhaust is tight. I'm not sure what else is there.
Thread Starter
|
New User
Joined: Sep 2021
Posts: 15
Likes: 1
The straight piece of air intake hose after the air filter is a little cracked at the connection but I sealed it off with duck tape.
Cargo Master
Joined: Nov 2009
Posts: 2,190
Likes: 620
How did you "check" them? If it's just a visual inspection, that doesn't mean a whole lot, other than verifying the gasket is there.
Trending Topics
Cargo Master
Joined: Mar 2010
Posts: 3,342
Likes: 294
From: Laramie, WY
When was the last time you changed the fuel filter?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Thread Starter
|
New User
Joined: Sep 2021
Posts: 15
Likes: 1
I sprayed carb cleaner around the gasket areas no change in idle
Thread Starter
|
New User
Joined: Sep 2021
Posts: 15
Likes: 1
What was the fuel pressure, and under what operating condition? Sometimes the pressure checks out at idle, but when under load and fuel consumption goes up, the pump can't keep up, and the system goes lean. Therefore I advocate checking fuel pressure under load. It can be a little tricky, but I tape the gauge to the windshield and go for a drive.
When was the last time you changed the fuel filter?
When was the last time you changed the fuel filter?
What is the normal operation psi range while driving. If it's low it's a tell sign a fuel pump problem?
Cargo Master
Joined: Nov 2009
Posts: 2,190
Likes: 620
Ok, so that leads me in 2 directions. A) Verify that the carb cleaner you used is actually flammable (I know, it sounds fecking stupid, but not all of it is, and I've gotten my **** bit by it before when using it to try and chase down vacuum leaks), and B) if you verify that it is, I'd start looking at fuel pressure and/or exhaust leaks.
Thread Starter
|
New User
Joined: Sep 2021
Posts: 15
Likes: 1
Ok, so that leads me in 2 directions. A) Verify that the carb cleaner you used is actually flammable (I know, it sounds fecking stupid, but not all of it is, and I've gotten my **** bit by it before when using it to try and chase down vacuum leaks), and B) if you verify that it is, I'd start looking at fuel pressure and/or exhaust leaks.
On the exhaust connection (ball and socket kind) I replaced the bolts, cleaned and sanded the rust around the connection for better seal.
Thread Starter
|
New User
Joined: Sep 2021
Posts: 15
Likes: 1
I don't recall off hand but it's running lean on bank 1. I'm not sure if it was upstream or downstream.
Cargo Master
Joined: Nov 2009
Posts: 2,190
Likes: 620
I generally use some Red or UltraCopper RTV on the ball/socket connection when I hook those up. I honestly don't know if it's necessary, but it's something that I just got in the habit of doing on snowmobiles over the years, as they use a similar ball and socket exhaust connector, and they're *much* more sensitive to exhaust leaks, being 2-strokes.
