lean under boost, almost stock w/190lph

[rstchris]

Ok, my car is a 98 gsx. It has the 6 bolt swap along with the first gen fpr (35psi) so i added an afpr set to 45psi. A 2.5" catless and a injen intake. Under boost the car gets leaner with rpm at a measly 10psi. I ported the wg so there's only one psi of creep and as soon as boost builds the fuel pressure drops to 30psi. I checked the afpr with a air comp. at idle and it's raising fp. I replaced the stock fp with a wally 190 and a new fuel filter and still the same problem. I just ordered a 255 but i'm reading that i shouldn't need it yet. There are no boost leaks and no fuel leaks. Any input will be great. TIA

 

[eclipsetuner_21]

Yep I would say it is your pump, its probably going bad or the sock is clogged.

 

[pboglio]

Take a volt meter and measure the voltage coming off the fuel pump electrical plug. If your pulling around 11 volts at WOT then a fuel pump rewire would be in order. But to be going lean at that low of a boost/power level something radical is going on. I usually take the factory fuel pressure tester, attach a gage and tape it to the outer windshield and go for a WOT pull and check the fuel pressure to make sure its rising with boost.

You didn't mess with the MAF honeycombs or MAF screw did you? If that checks out then I'd pull the injectors and have them sonically cleaned and backflushed by somebody like RC Engineering. What are your injector duty cycles and 02 voltages?

 

[rstchris]

I checked voltage at the pump under load and it held above 12v but I rewired it anyways, i tried the gauge taped the windshield trick with both pumps and got the same result. 48 psi idle, 55psi static, 40psi under boost. the MAF is untouched and the afr's showed 14.x@idle, 12.x static, 10.9-11.1 @ partial throttle and 13.0 and leaner @10 psi and gets leaner with rpm. I have an Inovate wbo2. Btw, pressure is consistant from the pump to the regulator, i put the gauge on both ends to look for line blockage.

 

[pboglio]

Exactly how are you connecting the vacuum boost source/line to your AFPR. Are you running it thru the fuel pressure solenoid or not?

 

[rstchris]

The stock fpr has the solenoid inline but the afpr does not, strait to manifold. I thought i covered all my bases but something is sneaking by me. The wally 255 should be here tomorow and i'll post my results.

 

[rstchris]

So, i pulled the 190 to put in the 255 and the fuel pump strainer is covered in snaut. Turns out there was urine in the gas tank before i got it and it turned to snaut and clogged the strainer so i got the super duper big strainer for now til i can drop the tank and clean it. Thanks for the help.

 

[habitatguy187]

Out of curiosity, what is "snout"?

 

[95redturboawd]

And why was there piss in the gas tank?

 

[habitatguy187]

And why was there piss in the gas tank?

, no kiddin'. Tell us a story.

 

[airmail96]

Yeah I am curious about the piss as well . Never thought it would turn into snout. Learn something new everyday.

 

[Spades]

I had this exact problem (lean mixture, not the piss in gas tank thing) when I bought my car, it had a 255 in there and it ran lean at WOT, I suspected bad pump so I ordered a new 190 since the car didnt have an AFPR on it, so while I waited for my order to arrive I had a spare OEM pump laying around and installed it, made no difference... A week later my 190 arrives and I look over the instructions and notice the O-ring is supposed to be installed on the other side of the spacer, whoever installed the 255 before me had it wrong and I reinstalled the OEM the exact same way. If not for the instructions I may have never known which way was correct, no leak would be obvious because it will be leaking right back into the tank. Anyway I go in and correct the O-ring installation and just to satisfy my curiousity I left the OEM pump in and suddenly plenty of fuel

 

[rstchris]

Yeah, snaut, not snout! The gas turned the urine into slime and gummed up the strainer. Aperently the previous owner brought the car to a shop to have repairs done, left a deposit and waited months. Later asked for the deposit to be returned aswell as the car so the disgruntled mech's put urine in the tank. , now it's my problem.

 

[datrip]

Man that is pretty wild. Pissing in a gas tank, .