never-ending lean condition: fuel pressure low? bad pump? VOODOO CURSE?

in the million-year effort to diagnose why my car is still running lean, i've been doing some more poking around...

i think my fuel pump itself is going out (walbro 190). i did a bunch of reading on tuners and the only thing i hadn't checked for was crimped fuel lines. i cycled my pump last night and checked everything from head to toe, and there's def no leaks anywhere and all the hardlines look immaculate, besides for being insanely dirty.

however, while the pump was running i squeezed the fat rubber line that comes down from the top of the tank and could feel the fuel PULSING. shouldn't it be one continuous stream of pressure? it was like i was squeezing my dick after sex, i could feel it throbbing like a heartbeat, instead of just staying pressurized continuously.

spark plugs are still whiter than my ass and the motor gets hotter than hell after 10m of idling.

getting my AFPR w/gauge back today. gonna hook it up and see what my pressure is at. any other thoughts?

btw i checked the voltage at the fuel pump and its ~14.1v, rewire still holding strong. there's only about 80K miles on the pump, could it be bad already?

Could be a timing issue dude... if your engine is running that hot, you may not be getting any timing advance.

Hey Matt, have you messed around with the thermostat? I know it has anything to do with A/F mix, but it can keep the engine hotter than usual. I just got my engine temp measured and it was 209 deg and our stats are set at 190 deg. If you go to a parts store they only have 180 and 170 deg. I just got 170 deg stat to keep it cool for the summer months.

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Originally Posted by mko

Hey Matt, have you messed around with the thermostat? I know it has anything to do with A/F mix, but it can keep the engine hotter than usual. I just got my engine temp measured and it was 209 deg and our stats are set at 190 deg. If you go to a parts store they only have 180 and 170 deg. I just got 170 deg stat to keep it cool for the summer months.

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No, no, no.... all fucking around with different thermostat temperatures is going to do is cause your engine management to never exit warm-up mode. This would WORSEN this problem, negating the few degrees it lowers coolant temp.

DSMers get that problem when they go with 160 deg or lower since they have the aftermarket ones made for lower temp. I guess Ill know in a couple of days

Are you using something to tune your car? If so, what are you using?

Do you have non-stock injectors?
Are your injectors clean?

everything is 100% oem. no fuel computers or piggybacks or anything. timing is dead-on oem spec. the car, minus suspension and body kit, is verbatim to how it rolled off the factory floor. i don't even have any aftermarket parts, all oem.

you probably fucked something up when you decided to stand in the engine bay

is your egr system functioning properly?
is your PCV valve functioning properly?
are you vacuum lines, including your throttle body vac lines properly arranged and matched to the factory diagram? This includes all your solenoids.

Is your coolant fresh and healthy? How old is your thermostat?
As suggested, and for good measure(its cheap anyways) if you haven't already, you oughtta change your coolant to a proper 50/50 mix and instal a new OEM mitsu thermostat.

Peano did you check the hard lines under the car to make sure none of them are dented? Maybe the line is a little pinched just enough to mess up the fuel flow and cause this.

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Originally Posted by DOHCstunr

is your egr system functioning properly?
is your PCV valve functioning properly?
are you vacuum lines, including your throttle body vac lines properly arranged and matched to the factory diagram? This includes all your solenoids.

Is your coolant fresh and healthy? How old is your thermostat?
As suggested, and for good measure(its cheap anyways) if you haven't already, you oughtta change your coolant to a proper 50/50 mix and instal a new OEM mitsu thermostat.

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as far as i know, the EGR system is fine. valve opens/closes as normal, and no CEL.

PCV valve is good. all vacuum lines good. coolant is only 2 months or so old, fresh 50/50 mix from the bottle. thermostat could be old for all i know, should replace that.

but i really don't know it's any of these things. the reason i think it's fuel pressure is because when i disconnect the fuel lines immediately after turning off the car there's no pressure. it just leaks out lazily, there isn't even a minor burst. should be 38psi at idle and still hold pressure after turning off for a little while, which it doesn't...

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Originally Posted by Stewi

Peano did you check the hard lines under the car to make sure none of them are dented? Maybe the line is a little pinched just enough to mess up the fuel flow and cause this.

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i'll be rechecking trmw.....

I am assuming this "lean" condition was happening even on your previous motor...correct? If so...when did it start happening?

Before you turbo'ed?
While you were turbo'ed?
After you removed the turbo?

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Originally Posted by 4-G-rim

I am assuming this "lean" condition was happening even on your previous motor...correct? If so...when did it start happening?

Before you turbo'ed?
While you were turbo'ed?
After you removed the turbo?

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it was happening on the old motor, and that's what made it eventually go out. and that's why i'm so stressed trying to fix it on this one, so i'm not just swapping engines 3 times a year and blowing thousands of dollars.

it started happening while i was turbo. something changed in the car and i havn't been able to get it to run properly since. when i was turbo i would play with every combo of settings on the afc2, and the wideband o2 never changed; it was always lean. even after i removed the turbo and went back to 100% stock, wideband o2 was always lean. i've removed the wideband since to save some life on it, and the narrowband has never been normal.

way back in the day, when i would floor it, the narrowband would peg into the rich (show one solid green line all the way at the most rich position) and you could feel it pull. now it pulls like shit, and the narrowband barely gets into the green, if maybe by a few bars.

i know narrowbands are probably the most innacurate things since blind snipers, but the plugs are stark white, engine gets hotter than fuck, no fuel pressure after turning car off, and i can just tell. also now i'm springing leaks in gaskets on the block cause i think the excess heat is wearing them down. oil is everywhere.

i'm reaching my wits end with this car.....it's sad but true. i shouldn't have to spend thousands of dollars and every waking moment stressing and diagnosing. i've taken it into mitsubishi shops and it stumps everyone.

all that remains is the fuel pump and the ECU itself. i'm weary on replacing the ECU cause it's another triple digit expenditure, and the fuel pump isn't exactly cheap either.

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Originally Posted by peanotation

everything is 100% oem. no fuel computers or piggybacks or anything. timing is dead-on oem spec. the car, minus suspension and body kit, is verbatim to how it rolled off the factory floor. i don't even have any aftermarket parts, all oem.

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Wait a tick, a few posts back you said you were using a wideband and a SAFC2 to tune.

Since you upgraded your fuel system, have you ever been able to get a normal reading? I suspect that either you don't have the means to properly control the fuel system or that you put a turbo on there with the stock injectors and expected it not to run lean.

What is your injector duty cycle during your logs?

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Originally Posted by diablos991

Wait a tick, a few posts back you said you were using a wideband and a SAFC2 to tune.

Since you upgraded your fuel system, have you ever been able to get a normal reading? I suspect that either you don't have the means to properly control the fuel system or that you put a turbo on there with the stock injectors and expected it not to run lean.

What is your injector duty cycle during your logs?

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i was using a wideband and afc2 to tune back when i was turbocharged. since then, everything's been turned back to stock.

after i upgraded my fuel pump to a walbro 190, it ran normal/fine back in the day. then i went turbo and thats when the trouble started.

when i was turbo i had the dsm 450cc injectors. i don't know the injector duty cycles cause i've never had a logger. injector harness is soldered back together after being hacked for the resistor pack.

Maybe you got a replica walbro... I know I saw something about some bad one being sold on ebay a while back. I would start with a new one or regular oem pump since your not turboed anymore..

Hmmmm....you removed the SAFC and I am sure that you had to get the wires that had to be cut and spliced back to "stock" right? Wires that were spliced were reinsulated properly and the MAF wires were properly reconnected right? Not to make you feel dumb...but just asking questions just in case. :cool:

nah it's cool man, ask away. i'm sure all of this is caused by something really stupid i overlooked, that's why i'm asking you guys, it's gotta be something easy/obvious...

maf wires were reconnected and resoldered, electrical taped and covered with wire loom. teh ECU wires that I cut for the afc2, i just twisted back together and put tape on them. stupid, yes i know, but i'll be resoldering them later this week. i don't think that's the problem though, it's gotta be this fuel pressure bs

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Originally Posted by phizzalot

Maybe you got a replica walbro... I know I saw something about some bad one being sold on ebay a while back. I would start with a new one or regular oem pump since your not turboed anymore..

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i'm leaning on it. i bought my walbro from slowboy racing way back in the day, but that was 80K miles ago

Ok cool...well start checking the fuel system and diag from there. Have you noticed your MPG being worse than before?