Announcement

Collapse
No announcement yet.

fuel pump upgrade questions and how does the pressure relief valve work?

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
    #1

    fuel pump upgrade questions and how does the pressure relief valve work?

    hey all, 99 p71. The car exhibits extended cranking followed by a very very rough idle for a few seconds...only on startup though. Once it runs it runs well. It does this cold or warm.

    CYcling the key on/off a few times fixes the problem.

    Research has lead me to believe I have either a weak fuel pump or bad pressure relief valve in the tank.

    So here is my question. Where is this relief valve? I can't seem to find much on it. Is it inside the fuel pump, or is it a seperate piece??

    If it's a seperate piece then where can I find this item?

    Also, I see cheap walbro pumps on ebay....I assume it would be no big deal to replace my oem pump with a slightly higher flow pump?? Car is stock right now,...
    -1999 P71 Crown vic X LAPD..
    -1966 mustang, 5.0 roller crate motor, t5 etc
    -1972 maverick 5.0 roller crate motor with EFI and a Lentech AOD
    Tags: None
    #2
    I believe these still have a return line style fuel system, so there are technically 2 reliefs. One is in the tank, as part of the pump. Its basically like a blowoff valve for an air compressor. It should never actually pop unless you have a clog in the line. the other is the fuel pressure regulator itself, mounted on the fuel rail. Basically to test both of these, you put a fuel pressure test gauge on the fuel rail to make sure the fuel pressure is where it belongs. If it comes up normally before starting the engine, and maintains the proper pressure then you don't have problems with either part. What it sounds like is the anti-drainback valve in the fuel pump is faulty and allowing the system to drain down, or you have a leaky fuel injector or something thats draining pressure off.
    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC grandpa spec white and cranberry

    1984 Lincoln Continental TurboDiesel - rolls coal

    Originally posted by phayzer5
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

    Comment

      #3
      thanks...that helps a lot. my pops has a fuel pressure tester....so to hit him up to borrow it is my next step
      -1999 P71 Crown vic X LAPD..
      -1966 mustang, 5.0 roller crate motor, t5 etc
      -1972 maverick 5.0 roller crate motor with EFI and a Lentech AOD

      Comment

        #4
        Probably couldn't hurt to toss a fuel filter on there. It might be clogged and taking a few extra primes to build up pressure through the clogged filter.
        Originally posted by gadget73
        There is nothing more permanent than a temporary fix.
        91 Mercury CP, Lopo 302, AOD, 3.08LSD. 3g upgrade, Moog wagon coils up front, cc819s in the back. KYB GR-2 police shocks. Energy suspension control arm bushings. Smog deleted.
        93 F-150 XLT, 302, ZF 5-spd from 1-ton, 4wd.
        Daily--07 Civic Coupe. Bone stock with 25k miles
        Wife--14 Subaru Outback. 6-speed.
        95 Subaru Legacy Wagon--red--STOLEN 1/6/13

        Comment

          #5
          my 90 CV had similar symptoms, turns out it was the fuel filter. tap on it a few times and see if it will start then. its cheap and easy to fix.
          What happened here?

          Comment

            #6
            you guys are absolutely right...110k miles...I bet that thing is original....once it gets going, it never ever faulters...which is what makes me suspect the pump is ok....I'll replace that this week and report back
            -1999 P71 Crown vic X LAPD..
            -1966 mustang, 5.0 roller crate motor, t5 etc
            -1972 maverick 5.0 roller crate motor with EFI and a Lentech AOD

            Comment

              #7
              Replaced the fuel filter today...good news is easy as hell access right near the pass wheel. Bad news is that didn't fix the problem

              Fuel pump has to come out. Good news is I found I can swap the fuel pump without dropping the tank...that makes me so happy. I've been dropping fuel tanks in 5.0 mustangs for 10 years now when I need to swap a fuel pump. This swap will be easy as pie
              -1999 P71 Crown vic X LAPD..
              -1966 mustang, 5.0 roller crate motor, t5 etc
              -1972 maverick 5.0 roller crate motor with EFI and a Lentech AOD

              Comment

                #8
                Did you confirm the pressure was off? Fuel pumps usually don't get weak, they mostly work or they don't.
                86 Lincoln Town Car (Galactica).
                5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                91 Lincoln Mark VII LSC grandpa spec white and cranberry

                1984 Lincoln Continental TurboDiesel - rolls coal

                Originally posted by phayzer5
                I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                Comment

                  #9
                  no, and I agree, but all the signs are there...bleeding back on the fuel system and cutting out slightly on wot. I'll hit my father up, I think he's got a pressure tester...you're right, I should confirm all my injectors are ok. I'm getting a right bank lean code...and can't find a vacuum leak to save my life. Wonder what the chance of that code meaning that I have a lean injector or 2 is.
                  -1999 P71 Crown vic X LAPD..
                  -1966 mustang, 5.0 roller crate motor, t5 etc
                  -1972 maverick 5.0 roller crate motor with EFI and a Lentech AOD

                  Comment

                  Previous template Next
                  Working...
                  X