fuel pressure regulator ???

Discussion in 'Performance & Fuel' started by drradon, Dec 30, 2008.

  1. drradon

    drradon New Member

    I've been having persistent problems with my '99 silverado - when I start up in the morning, it seems to idle fine but when I take off, it begins to kick and miss and run really rough. Sometimes it will sort itself out but sometimes it won't. I've had the fuel pump, ignition module, plugs, ignition wires replaced but the problem persists. I've been told to check the fuel pressure regulator but I need to find a diagram of where it is: I've looked at a couple of sites - but the diagrams don't look like my engine. I've begun to think the engine is a '98 model rather than a '99. It was purchased in early 1999.

    Two questions: is there any easy way for me to tell what model year the engine is (it's a 4.3 l engine)?
    If so, will I need to remove the intake manifold to get at the FPR?

    Many thanks.
  2. sdavis2702

    sdavis2702 New Member

  3. drradon

    drradon New Member

    That's what's making me crazy - I can't find the d***d thing - when I look at my engine, the fuel rail seems to be buried. Mine is a 4.3 l engine too - but when I looked at the online manuals on the Ohio library site, my intake manifold doesn't look anything like the '99 diagram - but looks more like the '98. For the '98 model, the manual says I have to pull the upper intake manifold off - but I'll feel like a prime fool if I do that and still don't find the FPR.
  4. sdavis2702

    sdavis2702 New Member

    If you're sure that the engine you see under your hood is not the one you're seeing online for your year, shoot a picture and let us see. That's kind of strange but very possible that someone has made a swap in the past.
  5. drradon

    drradon New Member

    Photo of engine

    Thanks sd2702
    I'm a little new at this but I've attached a couple of photos of the engine from right side and left side - with the intake housing removed.
    Again, this is a 4.3 engine in a '99 model. It was originally purchased in late '98/early 1999

    Any thoughts would be greatly appreciated.

    and Happy New Year...



    [​IMG]

    Attached Files:

  6. MrShorty

    MrShorty Moderator

    My first thought is: why are we spending all this time looking for the FPR itself when testing the FPr mo9stly requires finding the test port in the supply line (kind of looks like a tire stem or AC test port) and attaching a fuel pressure gauge to it.

    In the second picture, I can see the fuel supply and return lines (not sure which is which) coming into the top of the fuel meter body just behind the throttle body. I don't see the test port, but it should be right there somewhere in one of those lines.

    FWIW, it looks a lot like the fuel meter body on my '98, and I would expect the FPR to be down inside the intake, just below where the fuel lines come out.
  7. drradon

    drradon New Member

    Hi Mr. Shorty,
    Thanks for your post - I guess at this point, it's simply knowing what I'm dealing with as much as anything else. I've seen a number of posts indicating that it was a gut-simple test and fix for the '99 engines - pull the vac line, check for gas, and spend 15 mins replacing if that was the culprit - in which case I'm a complete blockhead for being unable to find the bldy thing. If it's a '98, then maybe there's hope for me...
    In which case: what's a good place to look for a fuel pressure meter; what's it likely to cost; and do I need to test the truck on the road or can I test it parked (it seems to idle fine, and miss and buck mostly when I'm trying to make a modest acceleration); etc?

    Regards
    DT
  8. MrShorty

    MrShorty Moderator

    Any self-respecting parts store will carry a fuel pressure tester. I paid ~$40 several years ago at Pep Boys. I've seen the same one at Autozone for about the same. Harbor Freight sells one for $10-15, though I don't know about quality.

    Basic fuel pressure test involves hooking up the gauge, turning the key on to see what pressure the pump generates (My '98 calls for ~60 psi, I expect your '99 is the same). Start the engine, the fuel pressure should be within a few psi of the engine off value.Goose the throttle, and the pressure should increase slightly then back to the idle value. When the pump shuts off, the system should hold pressure for a significant chunk of time.
  9. scooby2b2

    scooby2b2 New Member

    Fuel pume pressure regulator

    2 words. FUEL FILTER!......I have seen this same problem on a few of the shreiff office tahoes and trucks. Either the idle problem or it runs fine till floored and engine just dies or cant get over 2k rpms. Plugged 20 buck fuel filter.
  10. kilroy

    kilroy New Member

    I too can't get over 2K RPM or it dies - even going at 70MPH (hils are hard to climb and forget about passing) I will have to go change the filter.

    The irony is that we went to pick up the truck, it was running, gf wanted to see the baby, and we asked for the truck to be turned off. After we were done visiting tried to start the truck and it would not it cranked and cranked and cranked, to the point of almost killing the battery. So I gave up yanked the battery charged it returned the next day and it almost but started right up, alittle difficult but it started. Then I drove it 35 miles it did not sputter but I had to coax it up to 70 ... even 80 (leagal at places in TX :) ) - again I could not pass and had trouble climbing hills. (sorry to be so chatty)

    I will go buy a filter and post my results back, I promise I will be briefer :)
  11. hunter541

    hunter541 New Member

    i haven't sen fpr problem with this engine if its running this poor you should get a sevice light on if not check the distributor cap and rotor and the distributor gear wear also and the shaft will oblong to good luck
  12. kilroy

    kilroy New Member

    Nope fuel filter did not help. I am going to go look at hard starting also.
  13. kilroy

    kilroy New Member

    Man I thought the 2K rpm was a give away for the fuel filter, changed it and nada same thing crank crank crank no start. Tested fuel pressure at the most 40-50psi. (should be 58-60 I think)
  14. wlstiger01

    wlstiger01 New Member

    i am having that same problem too my 2001 silverado 1500 has excessive cranking i replaced the fuel filter and still nothing i am going to try that method replacing the fuel pressure regulator and let you know how it turns out
  15. MrShorty

    MrShorty Moderator

    I've heard some say this engine needs at least 50 psi to start, so if you aren't getting above 50 psi, then your problem is somewhere in the fuel system. You've changed the filter, so we'll assume it's not plugged. Any sign of blockage/kink elsewhere in the supply line? If you get a pair of flat vise grips and do it without cutting the line, clamp off a rubber portion of the return line to see if the pressure goes up. If it does, then that indicates that the regulator is opening too soon. If the pressure doesn't change, it suggests that the pump can't generate enough pressure.
  16. kilroy

    kilroy New Member

    Holly molly!!! Since it was not the filterI wanted to make sure before I replaced the fuel pump or any other item needlessly I broke out my fuel pressure test gauge.

    What I saw was this the pressure was 50psi and it would not hold. (need 58-60) and it needs to hold.

    So to bypass the fuel regulator I put the fuel test gauge on the output side of the fuel filter.
    ---> The same exact thing.

    ( I might logically think that if it was higher (and held pressure) than at the test port that the regulator was bad.)

    I drained the tank, read somewhere else here if you run the pump (if you can) you can fill a gas can with the gas in the tank. I used a fitting on the output side of the fuel filter and ran a hose to a can.
    Then I jumpered with a big paperclip (or a fused jumper desirebly) pins 30 and 87.

    Disconnected the filler tube hoses.
    Dropped the tank, 5 nuts, 4 on the frame and one on the strap of the tank on one end.
    Disconnected wiring harness and ground to frame.
    Disconnected input and return tube fittings.
    There was also a rubber tube.


    Had to use a brass punch and mallet to twist the nut holding the fuel pump and float assembly in the tank.
    When I got the new pump in I jumpered the pump on again.
    I checked the pressure at the test post, wow 60 psi, and holding

    Voila the truck started quickly and now I could pass ,no more going 2000 rpm or less...and lots of power.
    :great:
    Last edited: Jan 25, 2009
  17. drradon

    drradon New Member

    the problem persists

    I finally got the time to put a pressure gauge on the fuel line and the pressure may well be low. When I turn on the key, the pressure jumps up to 60+ psi but then drops back to ~50 psi. I start it up and it again hits 60 but drops back to around 50. What I understand is that it is supposed to be 60 psi. This is after putting in a new fuel pump so it seems that it may be the regulator. The intake manifold doesn't look anything like the '99's that I've seen images or drawings for so I have to believe that it's actually a 98 engine (4.3 l). Can anyone direct me to a good site for information on replacing the FPR and an estimate of what it should cost me for the replacement?
    Many thanks
  18. clarenceg

    clarenceg New Member

    Fuel Pressure Reg

    The FPR is under the intake manifold upper, or plenum, and attached to the fuel meter valve. Just a little work to get to it. Remove the fuel supply lines and the valve body. You should replace the gasket set also. Good Luck
  19. drradon

    drradon New Member

    Problem solved

    Thought I would post a followup - after a good bit of frustration, my mechanic discovered that the throttle position sensor was the main culprit - nothing to do with the fuel pressure regulator. The exercise was complicated by a secondary problem - the distributor cap was apparently arcing when the truck was first started up in the morning. Very wet environment here (average of 10' or more a year) and cool night time temperatures - condensing in the rotor cap...
    Live and learn

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