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Cadillac Seville / Cadillac Eldorado Forum Discussion, Crappy day with many problems - 1998 ESC in Past Cadillac Vehicle Discussion; Originally Posted by Ranger Pretty much any brand will do. This is not a finicky or highly technical part. Yes, ...
  1. #76
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    Quote Originally Posted by Ranger
    Pretty much any brand will do. This is not a finicky or highly technical part. Yes, just pull the retainer clip and remove it. Make sure you get BOTH O rings out with it (and replace both O rings) and be sure to bleed off the fuel pressure first unless you want a gasoline shower.
    One O ring is near the diaphragm correct, where's the other O ring? And I know about the pressure ( been there, done that)

  2. #77
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    Is the diaphragm supposed to look like a door screen? Or a clear membrane? Cause I saw many tears in it. Can I just change the diaphragm or the whole fpr?

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    Re: Crappy day with many problems - 1998 ESC

    Two O rings.The black one around the nipple at the bottom and the blue one sealing the mounting cup.



    Here is a picture of the under side. The screen is just a final filter.



    Internally there is a rubber diaphragm that separates the top (vacuum) side from the bottom (fuel) side. Your diaphragm is ruptured. That is why you are seeing fuel from the vacuum nipple. There should be none. You CANNOT repair the FPR. Replace it.

    This explaines how it works pretty well.
    http://www.youtube.com/watch?v=Kub3q1-YNZA

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    Re: Crappy day with many problems - 1998 ESC

    The fuel line-looking pipe with the green cap on it is the EVAP test port. EVAP is the system that stores fuel vapor from the tank in a charcoal canister and, during steady cruise conditions, shifts to a fresh air purge of the canister in order to burn off the stored fuel vapor. The EVAP purge solenoid is on the throttlebody or next to the fuel rail, the canister, hoses, and tank vent solenoid are under the driver's side rear door frame rail.

    The PCV valve is usually not a tight fit.

    Install a new transmission vent tube. It clips (wire tie) to the side of the throttle cable bracket on the throttlebody. Good thing your transmission is not overfilled or there would be fluid all over the place.

    Post #70 for FPR notes.

  5. #80
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    Okay so today I dropped off a couple friends, and I looked through the DIC and my mpg is 10!!!! What the heck. I checked the fpr and still don't know what to look for, is the nipple / hose on the side supposed to be dry? I opened the top part/ dome of the fpr and the bottom half below that, screen was filled with gas. Is it supposed to be like this? I know it's frustrating dealing with annoying members but I have to get better gas milage somehow!

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    Re: Crappy day with many problems - 1998 ESC

    The bottom half of the FPR is immersed in flowing high pressure gasoline. The FPR controls the pressure delivered to the injectors by changing - rapidly - the amount of fuel returned to the fuel tank - the fuel pump runs constantly, putting out WAY over the controlled 41 - 47 psi required for our particular injector/power/flow requirements. That fuel pump, into a dead head, will blow fuel lines right and left. The FPR is what controls the rail pressure.

    The top part is a vacuum dome - intake manifold vacuum, a function of desired power level, moves a diaphragm attached to a needle valve - more vacuum (low power demand) the needle is almost wide open to bypass fuel back to the tank. Low vacuum (high power demand) closes the needle valve and delivers more pressure/flow to the injectors.

    The vacuum can part is DRY - the fuel/screen side is WET.

    If you fooled around with the FPR it's entirely possible that the lower (small) O-ring did not come out of the rail fitting. 10 mpg, friends aboard, short hop, city is entirely possible. You'll have NO idea of true fuel mileage under all conditions until you have several weeks of driving data stored in the DIC fuel computer - long term average. Short term (instantaneous) fuel mileage is useless.

    This is a generic FPR diagram - close to ours, but not quite. Same function exactly.

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    Re: Crappy day with many problems - 1998 ESC

    Did you pull the vacuum line on the FPR and check for fuel with the engine at idle?

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    I pulled off the U-clamp and lifted the dome. In the morning I'll check it again when I go to school. Didn't know I was supposed to take off the line. And I didn't expect 10mpg with MY driving. I drive like a grandma and try to coast whenever I can. And whenever I have the want of gunning it, on the display the mpg goes up. For instance before gunning 9.7mph after gunning it a couple times around town 10.9

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    Re: Crappy day with many problems - 1998 ESC

    I pulled off the U-clamp and lifted the dome.
    That's how you replace it. You lifted the FPR. Once again, pull the vacuum line at idle so there is fuel pressure in the fuel line under the FPR. Remember, fuel and vacuum are separated by the rubber diaphragm. The nipple and vacuum line should be dry. Study the diagrams and video.

    P.S
    10 MPG could be normal for your type of driving (whatever that may be). Short city drives will play hell with your mileage while a long highway cruise will keep it high.

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    Re: Crappy day with many problems - 1998 ESC

    Quote Originally Posted by eldorado_sean View Post
    So it's was hot but every time I stopped at a stop light I could smell something burning...When I stopped after, I popped the hood while it was on. And started digging around. The smell was strongest at the right side of the engine, where the surge tank is on my car.
    Sometimes the cam cover gasket seeps oil and a single drop on the exhaust manifold will give a smell of something burning. I had this for a while, and it has gone away on its own. You could probably check for this from the bottom with a flashlight while on a lift.

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    Re: Crappy day with many problems - 1998 ESC

    If you're watching instantaneous fuel mileage (actually, a lot of that indication is influenced by intake manifold vacuum) then all bets are off. It's fun to watch, but useless.
    TMS likes this.

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    Re: Crappy day with many problems - 1998 ESC

    Quote Originally Posted by Submariner409 View Post
    instantaneous fuel mileage (actually, a lot of that indication is influenced by intake manifold vacuum)
    I thought the instant economy was more about the metered fuel injectors vs speed (at a standstill the instant is 0mpg--which means stops and drive-throughs will seriously affect MPG).

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    Re: Crappy day with many problems - 1998 ESC

    Yes, there's more to it than simple manifold vacuum - and yes, idling and long idling stops kills gas mileage. If you have recently reset the long term mileage average and then sit, idling, for a while you can actually see the MPG click down. If the long term average has not been reset for a while (mine has not been reset since 2007 or so) then it takes longer - stopped or running - to change the average. I have no idea of the number/timing of data points stored to calculate long term gas mileage.

    Instantaneous mileage is fun to watch - for a few seconds. Otherwise it's pretty useless unless you're trying to drive with an egg under your gas pedal foot.

    Reset your long term average, fill up, and immediately drive a half hour on an Interstate. Let's say your mpg clicks up to 26 mpg by the end of the half hour. Now get off the highway, stop and idle for a half hour - 0 mpg. At the end of one hour since fillup your long term mpg will be ~13 mpg.

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    Re: Crappy day with many problems - 1998 ESC

    Quote Originally Posted by mtflight View Post
    I thought the instant economy was more about the metered fuel injectors vs speed (at a standstill the instant is 0mpg--which means stops and drive-throughs will seriously affect MPG).
    You are correct.

    The system uses the injector pulse width - which does factor in vacuum, but it does not use the vacuum reading itself (MAP sensor). This is quite accurate since the pulse width represents all A/F calculation made, and represents the actual volume of fuel used. The system does make an assumption or two, however - it assumes fuel flow per millisecond pulse width using a constant related to factory injector #/hr rating - whatever that is on this car, and it assumes the fuel pressure spec.

    Proof - if you change out the injectors for those of another non-factory size, the MPG readouts reflect the change in pulse width (higher flow injector = shorter pulse width to maintain proper A/F ratio), and you will find grossly inaccurate readouts. If it simply used vacuum or other bits of data, there would be no change.

    That said, if the system is stock, those INST numbers are actually accurate in the very short timeframe they represent - but that short timeframe means they are of no value.

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    Re: Crappy day with many problems - 1998 ESC

    Quote Originally Posted by drewsdeville View Post
    You are correct.

    The system uses the injector pulse width - which does factor in vacuum, but it does not use the vacuum reading itself (MAP sensor). This is quite accurate since the pulse width represents all A/F calculation made, and represents the actual volume of fuel used. The system does make an assumption or two, however - it assumes fuel flow per millisecond pulse width using a constant related to factory injector #/hr rating - whatever that is on this car, and it assumes the fuel pressure spec.

    Proof - if you change out the injectors for those of another non-factory size, the MPG readouts reflect the change in pulse width (higher flow injector = shorter pulse width to maintain proper A/F ratio), and you will find grossly inaccurate readouts. If it simply used vacuum or other bits of data, there would be no change.

    That said, if the system is stock, those INST numbers are actually accurate in the very short timeframe they represent - but that short timeframe means they are of no value.
    Thank you for that reply--it was very interesting! Now for the million dollar question: at what point is it better to shut off the car while waiting, than it is to remain idling?

    I am sure there is a formula with variables such as operating temperature or lower (at lower temperatures there is more gas spent to warm up the engine probably in part due to emissions concerns to "light up the cat"). But assuming operating temperature has been reached, and say you're at a drive through or at a long light at an intersection where you can get a fair warning... what is that magic number where it makes more sense to shut off the engine and restart it, much like a hybrid?

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