hardcore97

my brother just finished up his build which consists of an 82mm GSR, ls rotating assembly, ITR replica pistons, b16 head, pro1 cams, aem fuel rail, dsm 450's(cleaned and checked prior to install) stock FPR, stock IM and TB. got the car on the dyno and it was losing fuel pressure at 3k-3.5k and going stupid lean, pulled the pump and it had the complete wrong sock on it, sock was the dirtiest i have ever seen. replaced the fuel pump(new walbro 255) and fuel filter. took it out for some street tuning to see if the issue was solved, now it starts doing the same thing but around 5k. is it because of the stock FPR? like i said the fuel filter and pump are both brand new. i cant think of anything else that would cause it to do that. am i overlooking something simple? there should be more than enough injector there as this should only make a little over 200 whp. any advice is appreciated

AllMtrRex

What type of fuel are you using?

Sounds like rust/trash in the tank. I would pull the new pump and check the sock once again. Also replace the injectors with a set of stock ones for now if the sock turns out to be clean. Stock fpr is fine for that setup, it could be faulty but it would be a rare instance.

hardcore97

premium pump gas, i will let him know to check the sock again. might just drain the tank and see what comes out.

hardcore97

actually i forgot we drained the gas in the tank before the swap was put in because it was regular 87, i didnt see any excessive rust or dirt come out

AllMtrRex

The sock was dirty, and this is after you drained the gas before installing the engine.....

hardcore97

yes, the car had a walbro 255 when my brother bought it 3 years ago, he sold it to a friend, who sold it to a different friend, who sold it back to my brother. none of them changed the pump/sock so its been in there at least 3 years. we didnt pull the pump until we tried tuning it and saw that pressure was dropping the first time and replaced the pump/sock and filter. tomorrow he will pull the pump and check the sock again.

AllMtrRex

gotcha, I'd recheck the new sock and try stock 240cc injectors just to see if the same thing happens. Also make sure injectors are not leaking and wiring is in good condition to each injector.

hardcore97

he just mentioned to me that it used to sputter really bad when the gas got below a 1/4 tank and its below that now, gonna try putting more gas in it and see what happens. would be nice if it was that easy.

shiroitenshi

possibly faulty FPR? you said you replaced em, but you could have gotten the rare defect FPR.

hardcore97

what should voltage be to the fuel pump when the key is turned to on?

jdmh22eg2

It is sock filter. I am going thru same issue on my hatch. My. Ar sat for 2 yrs getting built and rust and old gas turned to ****. Dropped tank cleaned, recleaned. Installed new 255 and sock and with in 10 miles sock was horrible. I have cleaned my sock filter 2 more times and replaced sock another, and vac tank at pump baffles again. Finally making progress. If u have a nasty tank (may not see it) it will take a good while to get things straight


Have you acually tried to diag the prob or just throw parts at it. I would suspect the latter. Do a volume test aprox 1 pint of fuel off main incoming line in 15secs is standard

hardcore97

il have him check the sock again to verify if thats the issue.

hardcore97

just pulled the filter/sock. its still clean, took a metal rod and slid it along the bottom of the tank, didnt stir anything up

00coupe

here is a pic of the sock... the inside of the tank looks clean/shinny

AllMtrRex

Were the pro 1's degree'd in? Are you using a resistor box with the DSM injectors?

hardcore97

yes he is using a resistor box, no cams were not degreed in, not sure why that effect the problem with the fuel.

AllMtrRex

It won't. I'm just curious if the leaning out problem could be a result of a mechanical problem. Check voltage at injectors, replace injectors with known working ones, replace fpr with known working one, make sure fuel return and feed line are in working order.

hardcore97

Fuel pressure is 95 at idle. With the key on it reads around 40. Bad fpr? I don't know what else would cause it to be that high

bambam

:O

hardcore97

new problem. he just got a new fpr on it. idles around 44 psi but at WOT it drops to 20 psi. drops down with the vacuum line connected and disconnected. this wasnt with a load on the engine, this was just revving up.

raverx3m

iTrader: (1)

daaaamn.95psi at idle thts like over 100 psi pressure at the pump.

why you need so much pressure? set it to 50-55PSI with engine off.
i made that mistake and my fuel maps were all fked up i almost blew my engine up.
it was set at 65psi and would drop to 50 psi
my car was tuned at 45psi and it would run 11afr at idle and got to 17-18 at WOT..

i realized my dumb mistake and set the fuel pressure properly now it idles at 12.5 and 13-14 at wot. just from adjusting fuel pressure to where it needs to be

check for damaged fuel pipes? maybe rust got into them.

00coupe

Dont need that much pressure, that is why we said we are trying to get it down, at the time i didnt have an adjustable fpr now i do with a gauge, put it on it read 45 at the rail had one in the filter at the same time it read 95-100 turned out to be the nut or what ever its called that holds the fuel line onto the rail, swapped it with a different one and its fine now, doesnt lose fuel pressure at all now, i will post a pic of what caused and fixed the problem tomorrow

raverx3m

iTrader: (1)

wtf lol never heard that.
i know that the OEM fuel filter nut has a very small hole that restricts fuel flow but never knew it was that bad... im gonna go check my nuts now.

oh wait you mean the vibration dampener? the mushroom looking thing on the end of fuel rail. i had to replace mine as well. now that i remember i had same problem. i decided to **** with it and adjusted the screw. turns out its a bad idea. because cant tell where it supposed to be at after.

00coupe

It wasnt the holes restricted it, it was that the nut had no holes in it at all, the one i put on had the holes on it, in the pic the old one is on the left and one that fixed it on the right

JDMBoosted

Thank you for this 00coupe, if I hadn't found this thread I would be waiting another week for a new walbro unit. During tuning I noticed that my walbro was shitting out and going lean above 5 psi of boost so I replaced the unit and was in your situation except with over 100psi of fuel pressure with the engine running. Checked out my fuel damper and lo and behold looks just the issue i read here. Now I'm wondering if my old walbro unit was actually good but this thing was giving pressure problems at higher boost..