Announcement

Collapse
No announcement yet.

Fuel Injector Vacuum Leak

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Fuel Injector Vacuum Leak

    On my 86 Buick Century T Type LG3 3.8L V6 I was checking for vacuum leaks. I sprayed throttle body cleaner at the base of the injectors where they sit in the intake manifold and on one injector there was an increase in engine RPMs. I assume this means the o-ring at the base of the injector is bad? There is no odor of gas from the engine bay. If I let the car idle for several minutes the engine stumbles and stalls and I get lean code. How difficult is it to remove the fuel rail and injectors on my 3.8?

    #2
    I thought I would try to depressurize the fuel injection system by using a fuel pressure gauge attached to the fuel rail test port. On the gauge there is a drain hose and a brass button to press and I was hoping that this would drain the fuel rail but no gas came out. In fact, even pressing the Schroeder valve stem with a screwdriver results in no gas squirting out. Does this mean that in my car there is no fuel pressure in the rail when the engine is off?

    Comment


      #3
      Any engine over ten years old needs to have o-rings renewed.

      Generally speaking , no pressure holding after key switch has energized fuel pump, then FPR's check-valve, fuel-pump's, or an inline check-valve (if applicable)

      Comment


        #4
        Originally posted by 85_Ciera_Rebuild View Post
        Any engine over ten years old needs to have o-rings renewed.

        Generally speaking , no pressure holding after key switch has energized fuel pump, then FPR's check-valve, fuel-pump's, or an inline check-valve (if applicable)
        Thanks Ciera. I was worried because everything I've read has a big "WARNING you must depressurize the injection system by pulling the fuse or connections to the fuel pump and run the engine till it's out of gas before servicing" but I guess our engines are different. I'm nervous about removing the fuel rail and injectors because in a thread here some guys had a lot of trouble: https://www.a-body.net/forums/showth...Fuel-Injectors

        I've never done this and I'm worried that I won't get the fuel lines reattached properly and end up with all kinds of leaks and problems.

        Comment


          #5
          Im wondering if his initial key on, prime fuel system is working, but the relay for the engine running, fuel pump on, is working. If its running, and then stalls, that almost what it sounds like to me.
          Brian - Carpe Diem

          I dont have to love my president, or any god, to love my country!!
          More people have died in the name of "God" than in all wars combined thruout history
          01 Pontiac Aztek GT AWD 127k - 04 GMC Envoy SLT XUV 193k

          Comment


            #6
            Originally posted by T Type View Post
            "WARNING"
            Ever seen a piston melt?

            Comment


              #7
              Originally posted by Pontiac6ksteawd View Post
              ...If its running, and then stalls, that almost what it sounds like to me.
              I assume vehicle is running...with issue at idle. "...engine stumbles and stalls and I get lean code" Maybe fouled injector(s).

              Add a bottle of Techron with a full tank of gas, and go cruising for a hour, at 45mph+

              I've never had an issue with pulling injectors...I did it on a 3.8 years ago.

              Comment


                #8
                Originally posted by Pontiac6ksteawd View Post
                ...but the relay for the engine running, fuel pump on, is working. If its running, and then stalls
                On V6-2.8 engine, oil pressure controls fuel pump....not enough oil pressure, and pump quits working. Or weak oil pressure sending unit...I always replace this item when it controls fuel pump.

                Comment


                  #9
                  They dont have the same oil pressure operated system inbetween the 90* v6 and the 60* v6?

                  I admit a lot of knowledge about the 60* engines.. But am limited on the 90* engines
                  Last edited by Pontiac6ksteawd; 10-18-2018, 02:22 PM.
                  Brian - Carpe Diem

                  I dont have to love my president, or any god, to love my country!!
                  More people have died in the name of "God" than in all wars combined thruout history
                  01 Pontiac Aztek GT AWD 127k - 04 GMC Envoy SLT XUV 193k

                  Comment


                    #10
                    Originally posted by Pontiac6ksteawd View Post
                    They dont have the same oil pressure operated system inbetween the 90* v6 and the 60* v6?
                    First time I encountered an oil pressure switch controlling fuel pump was on a 1971 Vega GT. I'd have to get schematics to know if a relay was involved, back then.

                    I know some of later GM vehicles had a test lead to check fuel pump, around driver's side firewall area

                    Comment


                      #11
                      Originally posted by 85_Ciera_Rebuild View Post
                      Any engine over ten years old needs to have o-rings renewed.

                      Generally speaking , no pressure holding after key switch has energized fuel pump, then FPR's check-valve, fuel-pump's, or an inline check-valve (if applicable)
                      Install the new o-rings with a _small_ amount of approved silicone grease. I got some with my rebuilt injectors. This will help the seal, and also help with removal when the injectors need to come out.

                      Ken T.

                      Comment

                      Working...
                      X