The Dreaded Lean Code

[Xjorgeypoox]

For each 10 horse power you need 1 GPH or 2.6 LPH flow

So 200HP would need 2.6 x 20 = 52 LPH
300HP 2.6 x 30 = 78 LPH
500HP 2.6 x 50 = 130 LPH

That's the FLOW the engine needs AT the carb or injectors

Fuel pumps flow rate should be listed with 5/10psi(carb), 30/40psi and 50/60psi as those are the most common pressures used
And at 13.5volt, running vehicle is 13.5volt to 14.5volt, for racing vehicle with no alternator there can be a 12volt flow listed

As pressure goes up the pumps flow rate goes down, it doesn't drop all that much between 30 and 60psi

I think the EFI Rangers all used 90-110 LPH at 40psi, so were fine with 60psi change in 1998, Ranger engines were all well below the 300HP mark, lol
Even a V8 swap would work with stock pump, unless you were modifying the stock 302/5.0l V8

There is no benefit in using a higher flow pump than needed, the fuel line size also matters as well
But it doesn't hurt anything to use a higher flow pump

And this is the info I was trying to find/calculate.
This is great. I feel much better about this fuel pump. I’m sure this will be the end to my lean running issue.
I’ll be sure to post an update as soon as I get this pump in and data logged

 

[Xjorgeypoox]

buddies old fuel pump finally came in... surprise surprise there’s a walbro in there!
The new kemso has been wired in and installed and sender assy has been thoroughly cleaned out.
It was nice for my soldering iron to take a poop 3/4 of the way done. So soldering isn’t the prettiest, but it will hold. Put heat shrink on both wires and added extra security to the hot wire.

my other buddy is coming over this Sunday so we can pull the bed off and replace this pump!
Any tricks or things to watch out for?

 

[Xjorgeypoox]

Alright fellas!
Another update. Got the new fuel pump in as well as new MAF sensor.
Truck is night and day running way better. Idle is smoother and power has returned.

Fuel trims in bank 2 are still a bit high, but I was able to get all sensors to now read as passing for emissions, and CEL has not come back on. Could a faulty DPFE sensor lead to higher fuel trims than should be? I’m just concerned that with driving the truck around, sooner than later those lean fuel codes could end up returning....
Thanks everyone!

*edit* I should note, fuel trims seem a bit erratic, but I would chalk that up to the computer relearning it’s fuel trims... I could be wrong though

 

[Dirtman]

You need to drive for a while for all the values to readjust. Put a full tank of gas worth of driving on it of mixed highway/city driving and then check again. The computer puts each little engine load/rpm range in whats called a cell. Each cell needs to relearn from idle to wide open throttle. None of those numbers are necessarily bad or in the slightest bit harmfull to the engine. The computer is back in full control (lean code goes off when the computer can no longer compensate). I've been through this, you will drive yourself nuts trying to focus on the numbers. Let it be, check again later.

 

[Xjorgeypoox]

You need to drive for a while for all the values to readjust. Put a full tank of gas worth of driving on it of mixed highway/city driving and then check again. The computer puts each little engine load/rpm range in whats called a cell. Each cell needs to relearn from idle to wide open throttle. None of those numbers are necessarily bad. I've been through this, you will drive yourself nuts trying to focus on the numbers. Let it be, check again later.

Great. I’ll have to do that.
Only thing kind of really making me scratch my head is the maf reading.
from what I understand, the g/sec reading should be closer to the 3.0 since I have a 3.0 engine... this being a brand new maf, why would it still report almost double the amount of air required? Any ideas?
Or am I misunderstanding something?

 

[Dirtman]

Those readings are a snap shot. Like taking a picture of a fast moving object, they will be "blurry". Scan tools differ in refresh rates (the time per second that they update the data) its not an instantaneous feedback unless you have s reaallly good scanner and even then, the data is only really good when graphing. Your looking at a Polaroid picture of F22 flying at mach 2 lol.

 

[PetroleumJunkie412]

View attachment 45847View attachment 45848
buddies old fuel pump finally came in... surprise surprise there’s a walbro in there!
The new kemso has been wired in and installed and sender assy has been thoroughly cleaned out.
It was nice for my soldering iron to take a poop 3/4 of the way done. So soldering isn’t the prettiest, but it will hold. Put heat shrink on both wires and added extra security to the hot wire.

my other buddy is coming over this Sunday so we can pull the bed off and replace this pump!
Any tricks or things to watch out for?

That explains it.... NEVER buy a Walbro pump..... Complete sh*t.

 

[Dirtman]

That explains it.... NEVER buy a Walbro pump..... Complete sh*t.

Or Spectre or airtex....

 

[Dirtman]

I know ill catch crap for this but....

My factory fuel pump on my 2009 was loud as crap, massive whining noise. Still perfect pressure but annoying. I started filling with a few tanks of shell nitro+ (only comes in 93 octane). After two tanks my pump is silent. I don't drive the truck enough to care much about the extra cost and don't need the octane but that shell nitro crap is really good fuel. Did some research and from what I found (and experienced,) its not a gimmick. It has way more cleaners and lubricant in it than any other gas. Plus max ethanol is 5% instead of 10% if i understand it.

I don't usually buy into gimmick fluids but i actually think this stuff is worth it if you dont drive the truck much and wanna keep the pump/fuel system clean. If you put major miles on then the cost is probably too much. Stuff is like 60 cents more per gallon.

 

[RonD]

The "rule of thumb" you are thinking of is when engine is at 500RPM, and its 1g/sec per Liter
so a 3.0l at 500rpm would show about 3 to 4g/sec

Yours was never at 500rpm, most engines don't idle that low

The 800rpm and 7g/sec looks right but also depends on elevation, outside air temp and humidity
MAF measures the WEIGHT of the incoming air, computer already knows the VOLUME of air coming in at any RPM and throttle position, thats just straight math, its a 3 LITER engine
What computer doesn't know is the WEIGHT of the air, how much oxygen it has in it, thats what the MAF and air temp sensors are for

But in general it looks fine

 

[Dirtman]

The "rule of thumb" you are thinking of is when engine is at 500RPM, and its 1g/sec per Liter
so a 3.0l at 500rpm would show about 3 to 4g/sec

Yours was never at 500rpm, most engines don't idle that low

The 800rpm and 7g/sec looks right but also depends on elevation, outside air temp and humidity
MAF measures the WEIGHT of the incoming air, computer already knows the VOLUME of air coming in at any RPM and throttle position, thats just straight math, its a 3 LITER engine
What computer doesn't know is the WEIGHT of the air, how much oxygen it has in it, thats what the MAF and air temp sensors are for

But in general it looks fine

Wanna pet my goats?

 

[RonD]

Wanna pet my goats?

Not unless their EYES are CLOSED!!!

 

[Xjorgeypoox]

The "rule of thumb" you are thinking of is when engine is at 500RPM, and its 1g/sec per Liter
so a 3.0l at 500rpm would show about 3 to 4g/sec

Yours was never at 500rpm, most engines don't idle that low

The 800rpm and 7g/sec looks right but also depends on elevation, outside air temp and humidity
MAF measures the WEIGHT of the incoming air, computer already knows the VOLUME of air coming in at any RPM and throttle position, thats just straight math, its a 3 LITER engine
What computer doesn't know is the WEIGHT of the air, how much oxygen it has in it, thats what the MAF and air temp sensors are for

But in general it looks fine

Sounds good.
So driving the truck around, for nearly 3/4 of a tank (lots of driving past few days) bank 2 fuel trims are definitely much higher than bank 1. Bank 1 stays around 6-7 ltft, while bank 2 hovers around 12-18.
no fuel trim codes, but EVAP system fluctuates between passing and not passing.
Looking through pages and pages of threads, it seems 1 of 2 things is going on.
1. Lower intake gasket is possibly leaking on bank 2
2. (Unlikely but possible) o2 sensor on bank 2 is failing.
All in all, I could theoretically pass emissions test right now, but I obviously want the truck running properly.
Thoughts?

 

[RonD]

Exhaust manifold leak on bank 2(drivers side) as well

O2s start to fade lean as they run out of chemicals, 125k miles or so

Both the above are "false" leans, pull a spark plug on bank 1 and bank 2 and have a look at the tips, if bank 2 is a little darker you have "false" lean

Vacuum leak is a "true" lean, meaning computers air data was incorrect, so spark plugs will look the same on both banks, because computer corrected for the unreported air so burn was good

 

[Xjorgeypoox]

Exhaust manifold leak on bank 2(drivers side) as well

O2s start to fade lean as they run out of chemicals, 125k miles or so

Both the above are "false" leans, pull a spark plug on bank 1 and bank 2 and have a look at the tips, if bank 2 is a little darker you have "false" lean

Vacuum leak is a "true" lean, meaning computers air data was incorrect, so spark plugs will look the same on both banks, because computer corrected for the unreported air so burn was good

Great info!
Other than pulling off parts and replacing them, is there a way to test intake gaskets and exhaust gaskets?
I’ll be pulling off spark plugs in the next few days and checking them out