How to check for a faulty FPR (Fuel Pressure Regulator) and replace it - Page 3
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Cadillac Tech Tips - How to fix it Discussion, How to check for a faulty FPR (Fuel Pressure Regulator) and replace it in Item Specific Cadillac Discussion; just got back from orreillys website they have a coolant temperature sensor for the fuel injection, not for the gauge,or ...
  1. #31
    a.johnson1's Avatar
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    just got back from orreillys website they have a coolant temperature sensor
    for the fuel injection, not for the gauge,or emissions. im not positive on its location it should screw in somewhere. i replaced one on a late 90s gmc with almost identical symptoms it was on the front end of the intake. do you think its worth 20 bucks to give it a whirl? Also do you know what the fuel pressure should be?

  2. #32
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    I suppose for $20 it might be worth a shot. Fuel pressure should be about 45 psi if memory serves me correctly.

  3. #33
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    thank you Ranger for all the advice it was very usefull in narrowing down my cars problem. I dont have the sensor yet, but when i get it in i will let you know if it helps. Thanks again Ranger


    Austin Johnson

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    AnotherToothpick is offline Cadillac Owners Member
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    Where might I find the FPR on a 4.9L engine, and furthermore, should I even bother? What I mean to say is, was this a N*-specific issue?

    I'm trying to pin down whatever may be causing various problems I've been experiencing, including extremely poor milage (<10mpg), a very rough idle (800-1000rpm), and sporadic knocking.

  5. #35
    behind-bars is offline Cadillac Owners Connoisseur
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    Quote Originally Posted by AnotherToothpick
    Where might I find the FPR on a 4.9L engine, and furthermore, should I even bother? What I mean to say is, was this a N*-specific issue?

    I'm trying to pin down whatever may be causing various problems I've been experiencing, including extremely poor milage (<10mpg), a very rough idle (800-1000rpm), and sporadic knocking.
    i think i found it on the 4.9. Look under the air filter housing, It has a vacuum hose coming out the side if I am correct. Looks sorta like the one in the picture but is attached differently.

    For the poor mileage I would suggest replacing the oxygen sensor, it is located just infront of the firewall and just behind the engine in the exhaust system. It brought my mileage from 9 to almost 14 without giving a service engine light. Also have you done the plugs/wires cap/rotor on it recently?

    Knocking may be caused by cheap gas, bad timing ( which may cause Idle problems to) or problems with the egr tubes or solenoid/valve ( which could affect all 3 problems)

    I would start with the cheap/free fixes first and clean the throttle body and egr delivery tubes which could raise mileage and cut knocking, also get on the oxygen sensor if you haven't, its only 20 dollars to replace and easy to do yourelf. And check your timing also.

    If you haven't done the ignition system stuff like plugs,wires, dist. cap I would do that as well.

    And push off and warmer to get any error messages to help you guide your searching.

    The FPR can fail on any engine so its worth a check.

    I think all of the above has been covered well indepth in other threads that I have seen.
    Search "clean egr tubes" aaswell as "tuneup" and "o2 sensor" for a good start

  6. #36
    AnotherToothpick is offline Cadillac Owners Member
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    Thanks for the excellent response! Actually I've only had the Seville for about 2000 miles. It was previously a granny-mobile, so I got it with very low milage ($3000 with 65k). Of course, due to the nature of its previous ownership, many fluids were in dire need of changing, and it appears from the very limited records I got with it that no work had been done on it... at all. And to add to that, the car sat undriven in a parking lot for several months before I came along and bought it.

    In conclusion, if it can be cleaned, tuned, replaced, etc., I assume that it probably needs to be. I'll check out the FPR, and I'll definitely grab an O2 sensor if they're really that cheap. I'll also check out those tune-up threads you mentioned... Thanks!

  7. #37
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    I have one for you Ranger:

    On my 1991 Seville, I have an aftermarket FPR from Aeromotive that is also a boost-referenced regulator (no boost yet ). It is set at 2 PSI above stock ratings. As of late, I have been having some serious cold-start issues to where I have to either crank the engine for several seconds or turn the key off and on enough to build fuel pressure...

    I immediately checked the fuel pressure regulator at the vaccum port for leaks, to which I found none. The next thing I tested was the fuel pressure: upon initially turning the key, the fuel pump arms and the fuel pressure rises to where it should be, then it drops to near zero...As mentioned before, I have to turn the key several times again without actually starting the car to get the fuel pressure to stay constant and I also do that so I don't fry the starter (just replaced a bad one today).

    Any thoughts on this man?

  8. #38
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    WOW, sudden drop in pressure. If the pump quit operating, I would think the pressure would slowly drop as the injectors bled of the pressure. Since this is a sudden drop, something is dumping fuel back into the tank via the return line very quickly. Since you just replaced the FPR, and it is aftermarket, it would be highly suspect. That is where I would start. I am just applying some logic to what little I know of how the system works and taking a shot in the dark (from the hip).

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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    Quote Originally Posted by Ranger
    WOW, sudden drop in pressure. If the pump quit operating, I would think the pressure would slowly drop as the injectors bled of the pressure. Since this is a sudden drop, something is dumping fuel back into the tank via the return line very quickly. Since you just replaced the FPR, and it is aftermarket, it would be highly suspect. That is where I would start. I am just applying some logic to what little I know of how the system works and taking a shot in the dark (from the hip).
    Shazbot!

    Yeah, the pressure doesn't hold well at all on initial startup and I have to basically 'prime' the system before I waste energy on the starter by over-cranking.

    I've had this regulator on for well over a year, but that doesn't mean that it can't go bad, right? I still have a few old ones laying around that should still be good, so this weekend I'll drop one of those back on and see if that cures the problem and perhaps replace my adjustable regulator.

    Thanks for the prompt response

  10. #40
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    If that regulator is adjustable, maybe you can adjust it. It is pretty obvious that something is opening the flood gates and if I understand the fuel routing correctly, the return gate is the FPR.

  11. #41
    illumina's Avatar
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    Quote Originally Posted by Ranger
    If that regulator is adjustable, maybe you can adjust it. It is pretty obvious that something is opening the flood gates and if I understand the fuel routing correctly, the return gate is the FPR.
    That or something inside of the FPR is stuck open if such a thing can happen. If I recall correctly, this particualr PFR can be opened for repairs...I'll look into it and see what happens.

  12. #42
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    Is it also possible that the check ball in the fuel pump isn't seating at all? Just an additional shot in the dark lol...but damn, I wouldn't want to tear that down just to find out...kick the gas tank

  13. #43
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    Can someone validate the size for me? I just bought one tonight and am putting it on tomorrow. I have a 99STS.


  14. #44
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    Quote Originally Posted by tbombaci
    From the package:

    ACD# 217-1629
    GM# 12499841

    I paid $71 with California tax for the kit from a local Cadillac dealer.

    You will only need two tools for the job:

    1. 1/2" ratchet or nut driver to get the beauty cover off
    2. a small screw driver to pull the clamp from the FPR

    It is a super easy repair.

    Also, there are two types of FPR’s (according to the parts guy at the counter). They asked if I had a plastic fuel rail or the new stainless steel rail.

    I had my fuel rail replaced via a recall notice. The plastic rail will eventually leak gas.

    -Tom
    ok if there are two types of FPR and it makes a difference when ordering which fuel rail you have, then doe it not stand to reason that when they do the fuel rail recall that they would have to replace the FPR to fix with the correct fuel rail.And would this not answer alot of the problems folks have had after the fuel rail recall fix?

  15. #45
    Rich_M is offline Cadillac Owners Fanatic
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    Re: How to check for a faulty FPR (Fuel Pressure Regulator) and replace it

    Quote Originally Posted by sunpowered
    ok if there are two types of FPR and it makes a difference when ordering which fuel rail you have, then doe it not stand to reason that when they do the fuel rail recall that they would have to replace the FPR to fix with the correct fuel rail.And would this not answer alot of the problems folks have had after the fuel rail recall fix?
    I asked that question when I had the fuel line recall done. I was told that they use your original FPR. (They do check it) I think the retainer clip is different.

    Regards,
    Rich

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