car probs. 04 cavalier fuel delivery

Discussion in 'Off Topic' started by machiasmort, Oct 12, 2009.

  1. machiasmort

    machiasmort Active Member

    I realize this isn't a car board, but I've been researching this a lot and some of the guy's here are as good, if not better than the car boards! This is the reason I havn't been on!

    Car died suddenly on thruway after bucking a little, almost felt like clutch was slipping. No fuel pressure or fuel at injector rail... Fuel relay bench tested ok last night. No audible sound from f/p, the dang door chime isn't helping me diagnose at all! Scanner read P0171 "lean fuel condition" Problem is rather suspicious because I just refilled the tank prior and fuel filter was changed @ 20,000 miles ago.

    :idea:Ain't crawled under her yet, but should make sure the IRA didn't put a bomb in it after the bad mouthing of Republicans I did in the Combustion Chamber:jester:! Absolutely no offense, strictly joking!

    Time to do some crawlin arround with a test meter! Will get back, wish me luck, thanks!

  2. POPS

    POPS Member

    If you checked the relay and fuses and you can not hear the pump

    It is the pump. I had 3 pumps on 3 different cars all go south at around 260-280K...POPS
  3. give me vtec

    give me vtec Active Member

    that was my thought...

    If the pump is working you could unscrew the fuel hose before the fuel rail and see if some comes out. If you are getting fuel to the rail your injectors might be clogged... have you ever used a techron concentrate or other injector cleaner before??? I put some in after every oil change.

    If none of that works, you might want to think of the ecu... is it located under the hood or in the car? Some ecu's that sit on the engine side of the firewall are more susceptible to to the elements.... Have you tried to test the continuity of the wires at the injectors???
    Last edited: Oct 12, 2009
  4. eastwoodo4

    eastwoodo4 Member

    i would test to make sure im getting power to the fuel pump when the key is first turned on.if it is and the pumps not coming on its a fuel pump.which is usually the problem.

    lean fuel code could be a seperate problem[like vacuum leak]other than the one your having now.

    arceeguy said he was ase cert.ask him if you cant figure it out.
  5. machiasmort

    machiasmort Active Member

    No fuel to the injector rail. Is it safe to unplug the relay and jump power across the plug ends on the relay box,(to see if I hear the pump run)? I don't need to fry my PCM!
  6. eastwoodo4

    eastwoodo4 Member

    no pressure at fuel rail.fuse is good,chances r most likely a fuel pump.remember the fuel pump only comes on for a few seconds if you just turn the key to run.fuel pumps are a common thing that needs replaced.
  7. machiasmort

    machiasmort Active Member

    I'm glad they ain't building MPFI Ht's, I'd find another hobby!

    Thanks for all of the help and advice guy's! Because of my newly obtained knowledge, I will post in hope it will help another Brother...

    I got to thinking about everything, I stated earlier that I had bench tested the relay for my fuel pump and that everything looked electrically sound. An idea came to me, on all Cavi's, one of the poles out of four are supposed to be hot (as long as the key is in the on possition). A signal from the PCM energizes a coil (uses two poles) and pulls a contact closed connecting the hot wire to the remaining pole of the FP circut, telling it to run the pump.

    I'll be able to send a false signal by removing the cover of the relay and pinching the contact closed, this will utilize the voltage in the system and most likely (hopefully) not hurt anything!

    While it's the General consenus the GM's Union members were the fall of the Company (I argue that), why the flip would they not have an access cover to get at the fuel pump under the back seat??? This would make troubleshooting and replacement a breeze! You wouldn't have to drop the tank! What do I know, I was just an hourly employee who was at least smart enough to pull the back seat and see if the car was designed by somebody with half a lick of common sense... Obviously their Engineers were underpayed. They've only been making Cavaliers for 15 + yrs. Look on the net and see how many problems there are surrounding troubleshooting FP's for them! Too many to list! God forebid they should make it easier on one of their techs or loyal Customer. Then again, maybe the Engineers are as stupid as the Union hourly were?
  8. POPS

    POPS Member

    Mach...You can tell for sure if you hot wire from 1 post to the other where the relay is supposed to go. It will usally work for a little bit because the pump is toast and tripping the relay, because it is drawing too much power. By hot wireing it will tell you if it is the pump or the relay...If you have A/C the relay for it is usally the same...Swap EM...POPS
    Last edited: Oct 13, 2009
  9. POPS

    POPS Member

    You will NOT fry the PCM!!! Just do not run it for long...POPS
  10. machiasmort

    machiasmort Active Member

    Hey Pop's,

    Your 100% right, they are the same relay's AC/FP... That was an after thought of mine that hit me right before I just signed in again... Think I would have been smart enough, last night, to notice that they had the same part # !!! I only looked right at the AC relay when figuring out which way to re-plug the FP into the relay block!

    I found a plug nearest the hood release. It was obviously warm at one time because it was almost melted. I broke the housing trying to get it appart. Will have to solid wire it back together tommorow. Was it the prob.(we'll see)?????? They were the two heavier gage wires in the plug and seem to lead to the main harness that runs under the back seat (now removed). I'm baffled because while it seems to run into the harness (wrapped in tape), the wire chages color from blackish grey to greyish purple on opposite sides of the plug (no sensor), just a plug! Inside the harness (which leads to a metal plate under backseat), there is no wire of that thickness! This plate is the hoakiest setup, I've ever seen. Rivited in place, like a fighter jet that the adverage mechanic isn't supposed to work on, yet alone stumble upon!

    Right now my objective must remain, to figure out which wires power the pump and I don't know if it has a chasi ground or not yet! The stupidity in assembly amazes me! Going high tech is one thing (you know elect. everything), but making it mission immposible for your customer (changing wire colors at random) is another!

    I'm glad the wirring harness wasn't made in Canada! It say's "proudly made in Meixco" every three feet! They must have run out of wire at the factory or something (keep the line running), (use the checkered wire if you have to)!

    Thanks Pop's, and rest of the gang also!
  11. arceeguy

    arceeguy Active Member


    Does the car run at all?
  12. machiasmort

    machiasmort Active Member

    Yup, finally got her runnin, thanks Brother!

    Took me and my buddies 3hrs to re-install a fuel pump. The Dealer gets paid for 8hrs!

    Dropping the tank was no easy chore! That model year in specific is plagued by ignition problems. I trouble shot it w/ my meter for about 2hrs (tearing the interior appart) just to make sure, that was the problem!

    Mexicans make great laborers framming houses, roofs ect. Trust me, don't let one wire your car,LOL! They must have run out of wire at the factory or something? The color changed every three feet! I did find one socket right behind the kick plate that was nearly melted due to over amping the connectors! Had to bypass the plug and hardwire! This was not the plug noted in the GM service files, but a smaller one w/about 6 wires to it. They were the heavier gage wires in the block...

    Thanks for asking!
  13. arceeguy

    arceeguy Active Member

    Usually, an electric fuel pump is good for the life of a vehicle. (average being about 150K) The majority of fuel pumps run motors with carbon brushes and it is only a matter of time for those brushes to wear out. Fuel additives with powerful detergents can reduce fuel pump life by reducing the lubricity of the fuel and wearing the brushes prematurely. So be careful!
  14. machiasmort

    machiasmort Active Member

    Situation may partially be due to my neglect... Only changed the filter 3 X in 82,000 miles. Each time, I noticed a lot of ash or gunk in it.

    I've never had one appart! I will be doing an autopsey soon!

    I have no reason to disbelieve you on the "brushed motor", I always figured that they'd be PM motors... How the heck do they keep them from blowing up the tank? Same thing w/ a sump pump... How do they keep the contacts from shorting?
  15. POPS

    POPS Member

    What kind of cars are you buying that only have a life of 150K..?

    I parked a 92 Buick roadmaster at 375 K..Trans starting to act up,

    and did not smoke or burn oil. Bought another 92 roadmaster with 250K

    for $ 1400 and I use the old one for parts. I am going to pull the motor

    from the old one, (LT1-350) in the spring and throw a set of Brgs./Rings in it,

    and put it in my boat.

    I bet when I pull it apart there will be very little ware because at a 110K

    per HR., it only reved at 1500 RPM, so it was idleing all it's life.

    If you buy CH. stuff I can see where you only get 150K. After all

    They are basically BIC lighters. Ya use em, and ya toss em...Pops


    Good on you for the R+R of the pump. Glad it solved the problem...POPS
    Last edited: Oct 20, 2009
  16. machiasmort

    machiasmort Active Member

    LT-1's are no joke! My friend had one of the originals in a 70 and 1/2 Camaro! One of the top 10 fastest cars I've been in. Had 4.11:1 gears, dual 4bbl from the factory! We put a cam in it when I was like 15... One of the first cars I did anything major on. That thing would put you in the back seat! Honest toss up with my 69' 455 W-30 block Delta-88. He might have even got me off of the line because the front end used to lift!

    I drove a Toyota GT-SE whooohoo! Only a couple hundred in the US. Had to repo it in NYC! This car was serious!
  17. arceeguy

    arceeguy Active Member

    The motor is submerged in fuel. Gasoline circulates around the moving parts of the motor, and that helps keep it cool. the sparks are a non-issue since there is no oxygen for combustion. A plugged fuel filter will cause the motor to work harder, increasing amp draw. The increased amp draw will cause the brushes to arc more, wearing out the brushes and commutator faster. Three filter changes in 82K is pretty generous actually. When a mechanic tests you fuel pump, he'll check the amp draw and even put a scope on the power supply line to analyze the "noise" from the pump. You can tell if the pump has a shorted or open rotor segment with the scope.

    Hi POPS - I also take pride in keeping cars for a long time. 200K, 300K - no big deal for me. But you have to admit that we are a small minority of the motoring public. If you take a look in the junkyards around here, the clocks generally read from 120-160K miles. Many times, you can just pull the timing belt cover to find that the poor car was junked because the timing belt snapped and bent up some valves. In other words, lack of maintenance did them in. Other engines are sludged up from the lack of oil changes, or as the cars got older they started to consume oil and the owners never checked the oil level in between oil changes until the engines started making funny banging noises. lol

    I don't think that there is Chinese car for sale here in the USA, but I do own a small motorcycle built by Lifan in China. I bet it is as reliable as a Harley-Davidson. (a low bar, but a bar nonetheless)

    To the Harley guys - I keeed, I keeed!
  18. machiasmort

    machiasmort Active Member


    The lack of O2 makes sense to some degree but if that be the case, I'm surprised more don't blow up!!!

    How long should I give my timing chain before I change it? Yet another thing these cars are known for!
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