i wasnt sure what section to put this into so i figured general may be good or if it gets moved ill track it down.
ok heres whats going on with some background info first. i installed a walbro 255 lph fuel pump, cant remember the part number but its the one the guys on the quad 4 forum told me to use. its been in the car for id say about 3 months now, give or take. 2 weeks ago i sent the car off to get the exhaust done, 3 inch exhaust, mandrel bent, its tight but oh so pretty. a few days ago on the way to work the fuel pressure took a dive in a big way, about 12 psi according to my incar fuel pressure guage and it stayed around there. car idles like a bag and barely ran. i limped it to work from a block or two away form where it started. left it and assumed a tow call was in my future. when i pulled into work i turne the car off and then turned the key on, the pump is loud no doubt about that, my car is bare past the front seats so i hear it all.
the pump would grunt first and then turn on and pressure woundt go up at all. also i noticed that when the rpessure was about to dro the pump got really loud as if being starvedfor fuel, i was right in between a half tank and a quarter tank of sunoco 94, i fueled up the nite before.
i started thinking its gotta be the fuel pump, its done for, i went out on first break from work, about 1.5 hours after shift start and the car fired up and pressure was fine, no problems at all. so i drove it home, drove it around the next day and drove it to work today where it happened again. oh and the day after it happened i flled up with 94 just to make sure it wasnt starved for fuel. at first i was thinking maybe its bad gas, i work in a small town, fuel prices are high and not alot ofpeople will buy the 94, then a guy at work was saying it could be vapor lock, the new exhaust and the heat we;ve had could be causing a bad combination.
when it happened today the fuel pressure was all over the place, it wasnt holding steady but rather bouncing around. almost like theres air in the lines and its passing the sending unit in the fuel line. its weird, once again happened around the corner from ork so i limped it there and shut it off, turned the key back on and the pressure jumped back to normal, good and high where its supposed to be. turned the key off and on a bunch of times and it was still up, i didnt get a chance to start the car again bceause i was about to be late, came out on my first break again and she fired up and then tonite i drove it home again.
so right now im not too sur ewhat to think, tomorrow i plan on putter header wrap on the exhaust where it goes near the tank to make sure there isnt excessive heat hitting the lines or anything, who knows, might solve the problem or the pump might be showing me signs of early death. hope this makes sense, its late and im tired, anyone have ayn input on this at all?
parting out my built and boosted 97 z24 so4x4.com/cavy.html for pics and a parts list
hmm.
only idea i have is that when they were doing your exhuast they bumped your tank/ a gas line and fubar'd up your filter.
maybe try changing that. Or CHECK the wiring going to the pump.
good luck
Not sure if this applies but I know the GTP guys have a problem with the way the walbro gets it's fuel from the bottom of the tank and the way the stock sending unit is designed. The two sending units are very similar (size being the only difference) to a cavalier/sunfire. Here is a link to an article on the problem...
http://www.zzperformance.com/articles1.php?id=40
I have no clue if that is what is causing your problem but something to think about.
Quoth the Raven 'Nevermore
raven@accesswave.ca
Raven Autosports
55 McQuade Lake Cres,
Halifax, Nova Scotia, Canada
(902) 850-3330
10.82@132
hmm good read there. makes sense. heres what im finding, its only bad on hot days. today was cool and i did a solo2 event all day and had no problems. saturday i went out of town and on the hiway it was fine, no issues at all, and it was a hto day, once i got into town it gave me the problem 3 times, nbut after a few seconds of sputter, i kicked the throttle a bit and it woke back up like nothing had happened. and the drive home today from nearly an hour and a half away was fine, even in the city and it was a cool day, so its somehting with the heat. i wrapped the exhaust in header wrap but i think i need to wrap it down further still, i was thinking that maybe the fuel was evaporating in the lines right above the exhaust before it had a chance to get anywhere, mainly because sitting in the city in traffic or whatever the car wont use much fuel and the hot fuel will barely flow. but on the hiway at speeds its using more gas than it would say sitting in traffic
parting out my built and boosted 97 z24 so4x4.com/cavy.html for pics and a parts list
Good read Raven. Thank you. I understood when I installed my fuel pump that I would have "run out" of gas before my tank was empty, and I understood why, I just haven't thought of a good way to fix the problem. I wanted to come up with something concrete before I dropped the tank again. I thought that would be what this thread is about, but I guess not. I guess I can't contribute much here, but did the author of that article come up with a fix? My only plan was to get a stock pump assembly, and figure out a way to make my Walbro work in that. I just cut the bottom of the cup so that the pump drew directly from the tank... the only thing I could think of was to extend it's draw somehow, or lower it a bit.
<img src="http://www.saskjbody.org/iB_sjc/uploads/post-9-45611-matt_pt.2_2.jpg"/>
Painting the Z - one inch at a time!
only fix is a new pump or to have this one rebuilt. its the pump for sure, its worse and i talked to a friend whos had similar problems and he said its the pump, gets bad on hot days and in the city, on the hiway its fine.
guess i should have read a bit more before running the tank down below a quarter, lol. oh well, atleast everything is still clean undetr the car from the last time i did it and wont be too bad to remove, guess i found a task for the weekend, that or drinking, lol
parting out my built and boosted 97 z24 so4x4.com/cavy.html for pics and a parts list
Does it do it when your given it gas? From a stop and then hit the gas? Or just anytime? I had a problem like this it was a FPR.
FU Tuning
itll happen randomly, its fine on the hiway or on a cool nite. but in the daytime when it gets warm it just does it randomly in the city. at a light, while driving, anytime it wants. i talked to a friend the othe rnite and he had a similar problem withhis pumps. i sucked air into it, @!#$ happens and now i get to replace it again, lol. anyone have the number for walbro? see what they say about warranty work or something. if not theres a lcoal place that rebuilds pumps, cant be too much to rebuild it
parting out my built and boosted 97 z24 so4x4.com/cavy.html for pics and a parts list
My car is having the same problem.When its really hot out,the car would sputter like its running out of gas.When im on the highway or at a steady speed its fine.When im driving in stop and go traffic it starts doing it.It did it just a couple of hours ago.I was getting ready to take off,and the car would barely run.I pulled over and my fuel gauge on the rail was reading almost no fuel pressure.The engine was just running on fumes.Than all of a sudden it jumped back up and the car ran fine.One thing i do notice when this happens is that the temp gauge reads very hot.My fuel mods are:walbro intank and an accel adj fuel regulator.At first i thought it may of been my injectors because i just got a set of stock ones from ebay and i thought they might have been clogged or something.Im gonna put the stock fpr back on and see if that helps.This problem started happening last week,so i havent really looked into it.
Peter
'06 Cobalt ss/sc W/G85 Package
Gm Stage II W/2.79" Pulley
K&N Drop In Filter
Custom Magnaflow Dual Exhaust
I'm thinking your FPR is the problem.
FU Tuning
judgez24 wrote:hmm good read there. makes sense. heres what im finding, its only bad on hot days. today was cool and i did a solo2 event all day and had no problems. saturday i went out of town and on the hiway it was fine, no issues at all, and it was a hto day, once i got into town it gave me the problem 3 times, nbut after a few seconds of sputter, i kicked the throttle a bit and it woke back up like nothing had happened. and the drive home today from nearly an hour and a half away was fine, even in the city and it was a cool day, so its somehting with the heat. i wrapped the exhaust in header wrap but i think i need to wrap it down further still, i was thinking that maybe the fuel was evaporating in the lines right above the exhaust before it had a chance to get anywhere, mainly because sitting in the city in traffic or whatever the car wont use much fuel and the hot fuel will barely flow. but on the hiway at speeds its using more gas than it would say sitting in traffic
now that u say that i think my car has had this issue once in a great while.
time i remember is when i was sitting in a mcdonalds drive threw and it was like 80 some degree's out and it was bogging down when i crept foward . then it did it right at that stop light when i pulled outta there. then next time i was there i think it acted up a little bit on me. I thought it was the greasy mcdonalds air not liking my car, lol. but this theory makes total sense.
I have the walrbo pump/ stock injectors/fpr and cartech FMU. basically 99.5% of the time the pump is perfect. I can live with it though. I do alot of express way driving.
How come we cant have a non ghetto fuel pump with these cars?. i mean we cant run it under a half/ 1/4 tank or it will fuel cut on us, now we find out that it acts up a little when it is super hot out.
arggggggggggggggggh
yeah when the fuel level gets low and you get on it you get that hesitation, that means your sucking air into the pump and burning it out. these pumps need fuel to kep them cold and the more fuel the better. i didnt realize that until after it ws too late and the damage had already been done.
its not your fpr, my problems the same, pressure will drop to virtually nothing, i think i was getting 12 pounds when it first happened and then itll come up by itself. the last time i did it i had to idle it about a mile to work.
your cars getting hot because its not getting enough fuel, another thing with engines is that if you lean them out, they will run hot and things will melt so be careful when your car acts up. mines been sitting since tuesday nite, its gonna get alot of things done to it over the next few week, finally gonna get my new oilpan on, relocate the batt like ive been meaning to, and get my turbo on and hopefully by mid september ill have the car back on the road to enjoy the last month or two before the white @!#$ falls
parting out my built and boosted 97 z24 so4x4.com/cavy.html for pics and a parts list
he's right check the FPR
Friends Don't Let Friends Drive Stock!!!!!
i always keep my car at a half tank or better. Suck we have such ghetto fuel pump set up's.
I am going to sand down the bottom of my gas tank and paint it with some 1200 degree paint and see what that does. Plus too from taking it in and out 2 times it has some nice dings and scratchs on it that i dont want to start to rust.
i will keep a eye on this (havent driven my car in a week or so due to me needing tranny mounts) fuel problem when i get it back on the road again. I really am not too worried about it, as 95% of my driving is expressway or a few stop and go lights and most the time i drive at night (work till 10pm) so i get on my car then
It makes sense about the heat problem. I think a FPR problem would be all of the time, where as this fuel problem has happened to 3 people on this post who have had their car running/sitting in hot conditions and they all acted the same.
that too is a great article from zzperformance.
I though about re wiring my fuel pump, but i only heard of one person doing it.
Ahh well, the car is running great and i knew my 135k fuel pump wouldnt be up for the demand of a FMU.
I want to know more about rewiring the stock fuel pump. When I replaced my stocker with the Walbro, it was because it was cheaper, and it seemed like a better alternative at the time. I'm getting sick of running out of gas just under a quarter, and having erratic power due to gas sloshing around in my tank when I'm below half. I'm starting to think I don't even need this "upgrade".
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Saskjbody president
i heard it was done b4 with a friend of a friend with a z24. My bro has it done on his dsm and it seemed pretty easy.
Ya it would be nice to be able to run your gas down low like normal, and not have fuel cut under a half tank under boost. But that is what u have to deal with on a boosted j body.
I really cant complain. From a full tank of gas to the half tank mark i get right around 300miles.
well te tank comes down today, going out there in about half an hour. i had her out last nite and it was cool, car ran good, pressure was still a tiny bit on the low side but it was good and then it wared up a little and the problems came back. so yeah, atleast i amanaged to ru the tan ka little lower than the half tank it was earlier that day. ill let you know what happens when it goes back together, although it might be a month or so since this week im changing the oil pan, reloacting the batt to the trunk and putting my little snail on
parting out my built and boosted 97 z24 so4x4.com/cavy.html for pics and a parts list
So,anyone ever figure out the problem?My car started acting up on me again today.Its def not the fuel pressure regulator.When it started to hesitate,i pulled over and there was zero psi on the fuel gauge.I checked the fuel regulator by pinching the return line,and there was no change in the fuel pressure.When i gave it a little gas,the car stalled out.When i started it back up it ran like normal.I dont know what the hell is wrong with this thing.
Peter
'06 Cobalt ss/sc W/G85 Package
Gm Stage II W/2.79" Pulley
K&N Drop In Filter
Custom Magnaflow Dual Exhaust
^ i think your pump could be bad.
today i cleaned up and painted the bottom of my gas tank with that 1200 degree paint, it was nicked up and rusty, eww.
i also tested my pump. when i pinched the return line going the FMU i got it to read just like it would with the FPR vaccum hose off (45-50 at idle, 55-60 with line off).
i pinched the line after the FMU. haha, the fuel pressure guage( on rail) shot up past 100 psi instantly and the car died.
so it is safe to say my pump is fine, knock on wood.
if it ever dies, i hope not, i think i might go back to the blazer pump, with the cut cup and blazer fuel pump sock. a guy i talk to says that works great for him.
good luck
im gonna cut u pmy cup before i put the pump back in, its all out im just waiting to habe it shippe dout by the guy that ordered it for me, walbro wont let me send it so he has to. dropped the tank and got it all out and apart ununder 45 minutes, but not the damn sending unit wont go into the tank all the way down, i wnana put the snap ring back on to keep it from evaporating but i cant seem to put it down far enough.
oh and despite what the instructions said online, you dont need to drop the exhaust, well not mine anyways and its 3 inch, you just need to shimmy it out from the around the heatshield, lol
parting out my built and boosted 97 z24 so4x4.com/cavy.html for pics and a parts list
Any update on this problem? Was it the pump? I am having the same problem with my walbro, only when it dies it will not start back up for the life of it. It usually wont start until the next day...
z24 aint afraid of no ecotec
