Fuel pump flowing too much?

[SVTContique]

So i was having some issues last fall, i thought it was my fuel pump going out causing me to run lean but it turns out it was my MAF was dirty. Anyways, before i figured that out i swapped my old 255LPH pump for an Aeromotive 340LPH pump.

The car has not really run right ever since then, I couldnt figure out if it was the MAF or something with the fuel. What happens is sometimes the car will be pulling fine, and then all of the sudden my AFR will just jump from 11.1ish to over 12 (lean). Usually this happens at higher RPM's but it seems to do it randomly.

Here is my question, is the 340LPH pump flowing too much and causing my FPR to fail? Could this be my MAF?

I have no CEL, its not a spark issue because its so random.

Thanks for the help.

 

[4vRedone]

What was your car doing

 

[98fourvalve]

Wait, I'm a bit confused... Last fall you had an issue (running lean) that you thought was fuel related so you replaced the pump with a 340, but it turned out to be a MAF issue, which you found out after you replaced the pump. But ever since the pump was replaced it has never ran right and has had lean issues at times?

 

[encasedmetal]

what is your fpr reading at wot? fuel pump wouldn't cause a lean condition unless it's maxed out or losing voltage due to battery issues.

 

[SVTContique]

Wait, I'm a bit confused... Last fall you had an issue (running lean) that you thought was fuel related so you replaced the pump with a 340, but it turned out to be a MAF issue, which you found out after you replaced the pump. But ever since the pump was replaced it has never ran right and has had lean issues at times?

Last year the car was running totally ****ed, i left it over the winter thinking the fuel pump was out of sorts (it had gotten louder), so when spring time came i started it up, car ran odd still, i swapped the fuel pump for the new 340LPH pump. Car was still being weird so i took apart my piping and cleaned it all and sprayed down the MAF with contact cleaner. That got rid of the problem i was experiencing. What is happening now is that my car will run fine (pull fine) and then all of the sudden my AFR will shoot up. No indication of why, it just does it randomly.

Last winter i couldnt even drive the car it was so bad. Now i can drive it, i just cant go WOT which is really annoying. It seems any sustained load and it starts to lean out. And i am talking like instant lean, like the car is fine, and then BAM, 12.5AFR.

what is your fpr reading at wot? fuel pump wouldn't cause a lean condition unless it's maxed out or losing voltage due to battery issues.

I dont have a fuel pressure gauge. Battery is fine, its a brand new one and my volts are fine all the way to redline, my datalog proved that.

Is there anyway to figure out more info via my datalog on what the car is doing? No OBD2 sensor for fuel pressure i am guessing.

 

[encasedmetal]

send me a datalog of the issue to [email protected]
I will need the following PIDs
analog 1 (your wideband reading)
coolant temp
IAT temp
maf ad counts
load
rpm
spark
TP absolute
battery voltage
fuel pump duty cycle

I don't care about stft's as you'll be in open loop when you try and go WOT (or past 555 maf counts for that matter) and the o2's aren't reading then anyways

 

[SVTContique]

I dont think i can data log my duty cycle. I dont remember seeing that option on my SCT.

 

[encasedmetal]

I dont think i can data log my duty cycle. I dont remember seeing that option on my SCT.

then do fuel pump volts

 

[1996MysticSnake]

Are you using the factory regulator?

 

[SVTContique]

Are you using the factory regulator?

Yes i am

 

[1996MysticSnake]

I would get a fuel pressure gauage and make sure the factory regulator is doing its job. I have seen guys complain about pressure issues when running aftermarket pump at high rpms