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?

hmm started when you went turbo and has been hot and running lean since then no matter what you do.. i would look at things that have always been there not things you changed.. the pump might be bad after many miles.. you say it pulls like shit now.. does it misfire at all??? or just no power at all???

heat issue might be radiator or thermostat, but these little engines do run really hot.. are all ur fuel lines stock or steel braided? as you might have a leak somewhere idk im stumped :017: :confused:

nah i've checked for leaks, everything's bone dry. i'll try to recheck tmrw with a lighter, hahahahahaha

i think the heat issue is because it's running so lean. i'll be changing the thermostat this week, and the radiator is brand new, 2000miles on it.

it just doesnt pull at all, and the motor is only 115K miles with great compression. keep changing the plugs every month cause they get so white.

going to inspect pump and recheck for leaks tmrw. check in-tank seals too. going to resolder the ecu and see if i can get the afpr installed

i just pulled my plugs today - white as snow....wtf......I guess I was running really hot.

worst feeling in the world ^. you running NGK copper regulars or NGK V Power?

for some reason all the VatoZones here don't carry the regular ones, just the v power ones. they're like oh yeah we have regular NGK copper plugs for your car; come back to the counter 5m later "oh we seem to be out of stock, but we have V power" UGH. i just want normal spark plugs

I use $2.50 spark plugs from Walmart. The last set lasted an year w/o a problem, but I have some NGK turbo ones for when go turbo.

i just dont get it man.. you took out the fpr when you took off the turbo i presume and you put ur old one back in i take it.. um.. it might be the regulator.. but this happened when you were turbo as well so idk im still confused

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Originally Posted by Galanttuner10

so idk im still confused

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yeah, tell me about it

0psi

i installed my aeromotive afpr today with the gauge. turned the car on. gauge reads 0psi.

has to be a faulty gauge, right? i'l be going to see if i can get a new one tmrw.

the car feels about the same and the narrowband o2 reads about the same, maybe a little more rich.

but now the fuel pump is making a new whirring noise thats on a different frequency than it's standard operating noise. W...T....F....

did you ever replace that fuel pump strainer sock?

You know there is a way to eliminate the fuel pump o-ring all together?

you cut just above the socket where the fuel pump outlet and oring slide into.

so now there would be just a straight tube on the fuel pump assembly.
Now you just get a 2" piece of fuel hose and clamp it to the pump outlet, and then to the hardline that you just cut.
done. never again will you have fuel pressure drop after you turn off the car.

I'm kind of thinking about what Kevin said with the wiring of the MAF.
Did you ever change ECU's when going turbo?
Did you do any rewiring of the injection system?

I feel the problem lies somewhere in the ECU telling the Injectors to open up more for the air that it is reading. Possibly you may have a faulty MAF that is causing the sensors to read less air than you actually have. Maybe you can get a replacement MAF form a JY just to see.

Or yyou could have a leak in your intake system that is post MAF. What type of intake pipe are you using? Does it have any holes that aren't hooked into the system that might be sucking in air? Are there any cuts in the couplers? Do you have a good seal where the intake pipe meets the throttle body? Throttle body to intake Mani sealed perfectly? How about Mani to the block? Did you get all the bolts in? Maybe do a leak test?

Are most of the intake parts the same as when you were boosted? It's Possible you damaged something minor while you were boosting. The leak was so small, you could adjust for it with the AFC2, and now that you don't have a managament system, the regular ecu won't compensate.

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Originally Posted by DOHCstunr

did you ever replace that fuel pump strainer sock?

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yup, replaced that. my old one was filthy...

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You know there is a way to eliminate the fuel pump o-ring all together?

you cut just above the socket where the fuel pump outlet and oring slide into.

so now there would be just a straight tube on the fuel pump assembly.
Now you just get a 2" piece of fuel hose and clamp it to the pump outlet, and then to the hardline that you just cut.
done. never again will you have fuel pressure drop after you turn off the car.

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i've thought about that since the pump started making this new whirring noise last night. IDK wtf this thing is doing, so i want to eliminate as many things as possible

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Originally Posted by Blue Ice

I'm kind of thinking about what Kevin said with the wiring of the MAF.
Did you ever change ECU's when going turbo?
Did you do any rewiring of the injection system?

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never changed ECUs. i rewired the injector harness to use the resistor pack with the 450cc injectors. since wiring it back to the oem injectors, i've resoldered the harness straight to the clips, oem setup.

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I feel the problem lies somewhere in the ECU telling the Injectors to open up more for the air that it is reading. Possibly you may have a faulty MAF that is causing the sensors to read less air than you actually have. Maybe you can get a replacement MAF form a JY just to see.

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already got a MAF from another 7G at the junk yard, using it atm.

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Or yyou could have a leak in your intake system that is post MAF. What type of intake pipe are you using? Does it have any holes that aren't hooked into the system that might be sucking in air? Are there any cuts in the couplers? Do you have a good seal where the intake pipe meets the throttle body? Throttle body to intake Mani sealed perfectly? How about Mani to the block? Did you get all the bolts in? Maybe do a leak test?

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oem intake pipe. no holes, i've checked it a million times. the seal at the TB is foreskin tight. TB to intake mani has a brand new OEM gasket. mani to block has brand new OEM gasket.

leak test is a good idea.........

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Are most of the intake parts the same as when you were boosted? It's Possible you damaged something minor while you were boosting. The leak was so small, you could adjust for it with the AFC2, and now that you don't have a managament system, the regular ecu won't compensate.

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all that i used when i was turbo was the maf, everything else was different and since has been removed or replaced.

thanks for all the advice everyone, i feel like i'm real close to getting this fixed, keep the ideas comin'.....

soldered the wires on the ecu harness that were spliced or cut&twisted from the afc2 days. also got a new fuel pressure gauge and put it on the apfr, dialed in factory fuel pressure.

nothing's changed.

it just hit me i'm using dohcstunr's 60mm TB still. going to swap my original 56mm back on, but i still don't think that's it. at this point there's not much left to do....

56mm? its more like 48mm

Man, get an accurate reading if the A/f ratio.

What kind of intake do u have - stock, ram or cai. Usually aftermarket intakes make your engine run lean, cuz they heat sink.

OEM intake. everything is OEM. everything. well, except for the fpr now, but i think the aeromotive is a step up from the oem.

i could throw in my wideband again, just means i have to get a bung welded into the downpipe. i'm really tired of blowing money on this thing; i'm tapped for cash right now so it will have to wait.....

hopefully the throttle body fixes it a little bit. i'm about to borrow a grand from my girlfriend and just drop it off at the stealership......

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Originally Posted by peanotation

OEM intake. everything is OEM. everything. well, except for the fpr now, but i think the aeromotive is a step up from the oem.

i could throw in my wideband again, just means i have to get a bung welded into the downpipe. i'm really tired of blowing money on this thing; i'm tapped for cash right now so it will have to wait.....

hopefully the throttle body fixes it a little bit. i'm about to borrow a grand from my girlfriend and just drop it off at the stealership......

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DONT BRING IT THERE!!!! lol cuz when you get it back that problem will be gone but something else will be wrong

id really want an accurate reading before i go all crazy as narrowband is inaccurate, but my narrowband can peg rich with a heat soaked short ram so somethings up... do you still have the original ecu or did u get 1 from a 96 2 match? i dont think there is a difference for the fuel cycle but you never know

nah, still on my weak-ass mysterious obd1.5 94 ecu. i wonder if the afc2 permanently screwed it up, because no matter what i dialed in, the wideband a/f never moved on a wot pull. EVER. i could crush everything -50% or go +50% across the board, do a wot pull, and the wideband never budged.

Take it to Arthur...he is a lot cheaper and you know you can trust him! Stay away from the stealership. Borrow the grand anyway though. If you think its the ECU...I have a 96 ECU sitting here. You can borrow it to see if it will help. Pay me for the shipping and you can have it. If it works...keep it. You did a lot for me with helping with my swap its the least I can do!

He has to swap many pins to get the 96 ECU working in 94 car

yeah i'm on the hunt for a 94 ecu right now, fed spec. that's the only thing i havn't replaced....lol....building a brand new car at this point

well i officially made the car worse.

up until this post, i had been running dohcstunr's 60mm GS throttle body. the more i thought about it the more i was like DUH! way more air = way more lean!

so i swapped the significantly smaller (original) OEM sohc throttle body onto the car, transfered the blockoff plate over (cause i hate the iac and fiav valves), double checked the vacuum lines.

before, the narroband a/f gauge would cycle a little bit into the rich.....now it doesn't even touch the rich side, and is more biased to cycling through the lean side. there is a definite difference, and the gauge is shower a much more lean condition.

i'm taking it in on thursday, i'm officially out of ideas. anyone wanna buy a kidney so i can pay for the bill? lol