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HOw TO JUMP FUEL PUMP RELAY

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    HOw TO JUMP FUEL PUMP RELAY

    I want to take out fuel feed like and jump fuel pump relay to see if fuel pump is working. How do I just relay or fuse? Which relay/fuse is it?
    sigpicGLETSCHERBLAU METALLIC with leather INDIGO LEDER interior and blue top.

    #2
    Fuel Pump relay is the middle relay on the bracket in front of the left hand side shock tower. I'm searching for the same answer though on how to jump... I'll let you know if I find anything. But at least now you know which relay it is. ;)

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      #3
      I'd like info for this also, except i have a 318is

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        #4
        Jumping a relay is probably all the same method. Locations might be different. I'm looking.

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          #5
          DaveSmed said: It's easy to tell if a relay is bad, but its much tougher to tell if it's good...

          For most E30 relays, grab a fresh 9v and stick it on pins 85, and 86. That's usually enough to get them to trigger.

          That tells you nothing about the condition of the relay contacts however, and that is usually what goes wrong. An ohmmeter can give a little better idea across 30 and 87 with the relay triggered, but is by no means a perfect test either as that has to carry 30 amps in some instances.

          StereoInstaller1 said:
          Throw it in a vise and squeeze.

          If it crushes, its bad.

          ^ but thats probably a lol.

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            #6
            ^ and that's all I'm looking at for tonight. Going to hit the hay. Will check back tomorrow though. I might try that 9v thing sunday just to see.

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              #7
              i do it all the time with mine to test the fuel pump, i just use a fused jump wire and connect center bottom(toward driver fender) and the center front(towards headlights) They you will here your pump running
              Your signature picture has been removed since it contained the Photobucket "upgrade your account" image.

              IX being restored here

              Ix turbo build here

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                #8

                Originally posted by Roysneon
                $5 shipped?
                Originally posted by MarkD
                You are a strange dude, I'n not answering any more posts from you.

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                  #9
                  OK, so I am gonna try and shed a little light for you here, you seem really stuck.

                  First, make damn sure you have a testlight. I mean a $5 cheapie is fine, they sell one at WalMart for $5.37 or whatever, that is just fine. I hear of you NOT having an actual LIGHT BULB I will quit offering any help...seriously, have a test light in your hand.

                  Even if you solder wires on a light bulb, I don't care...test light ONLY.

                  The reason is simple: a meter will read voltage even if it can't pass enough current, so you need some kind of actual "load". Light bulb = load, make sense?

                  Now, start with the first relay, the one furthest forward. That is your main relay. The main relay provides power to the fuel pump relay AND the DME. If it does not work properly, you get no fuel pump.

                  Remove the bracket that holds all 3 relays and flip it over. Grab your test light and probe the biggest of the 3 wires that make a row in the center of that relay. The test light should light up. Now, have someone else turn the key on while you are holding the relay block: that main relay should "click". As soon as it clicks, the other 2 wires (the medium red and red/white) should go live. If they don't, again, you have no power to the fuel pump...so you have to fix that first.

                  Now, assuming you have power to the input of the fuel pump relay (from that test you just did) it is time to test the fuel pump relay.

                  Remove the relay, look at the contact map on the side. You will see that "30" connects to "87" when the relay is switched. 30 is the wire from that main relay, 87 is the wire that feeds the fuel pump.

                  So, now that we have power going into the fuel pump relay (key on, main relay working) look at the bottom ("pin" side) of the fuel relay (oh yeah, that is the one in the middle, the rear one is the O2 sensor heater relay) look carefully at the terminals: they have tiny little numbers.

                  Here is the actual answer to your question: you jump from "30" to "87" to power your fuel pump.

                  You can shove a paperclip in the sockets if you must: I use a short hunk of wire with 1/4" male non-insulated "spade lugs" crimped on either end. Hell, a pair of needlenose will do just fine, but get the right pair jumpered: 30 to 87. Do not fuck that part up, read your shit carefully.

                  IF it does not spin up (early cars run BOTH pumps off the same relay) you need to test voltage at the pump. Go back to your transfer pump (main pump on late cars) that is under the hatch, under your back seat: use your test light to make sure you have power at the pump itself: no power means bad wiring (assuming the relay is still jumpered) but the reality is that mot likely, you have a bad main relay.

                  Figure it like this: that one little relay runs everything in your car, basically: fuel and DME. 20+ years is a LONG time.

                  Let me shed a tiny bit of light on that, too: every time a relay "opens" or "closes", there is a tiny spark. The tiny spark does 2 things: first, it eats a tiny bit of the contact (itself smaller than a pencil lead) and it makes a little carbon soot. Both the hunk of metal missing and the soot mean a crappier connection...multiply that by 20 years of starting and stopping the motor, you can understand WHY they fail.

                  Hope that helps: do a I say and you will have a working fuel pump in no time.

                  Oh yeah...the crush in the vise thing is true: if you crush it, it is likely bad.

                  Good luck!

                  Luke

                  Closing SOON!
                  "LAST CHANCE FOR G.A.S." DEAL IS ON NOW

                  Luke AT germanaudiospecialties DOT com or text 425-761-6450, or for quickest answers, call me at the shop 360-669-0398

                  Thanks for 10 years of fun!

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                    #10
                    Thanks Luke once again!

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                      #11
                      wow yes.
                      old, who cares. my brain just made a new fold in the car tech region.
                      thanks.

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                        #12
                        hopefully i can find some help here. I have an odd situation where i am getting no power from 30 and 12v from 87????????? how is that possible? I know the system worked prior to me pulling the engine. and no the terminals were not switched in the process. I am sitting here scratching my head.

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                          #13
                          Originally posted by MCreally? View Post
                          hopefully i can find some help here. I have an odd situation where i am getting no power from 30 and 12v from 87????????? how is that possible? I know the system worked prior to me pulling the engine. and no the terminals were not switched in the process. I am sitting here scratching my head.

                          need more details here. you probably did something wrong putting the engine back in

                          1989 Coupe build thread: http://www.r3vlimited.com/board/showthread.php?t=312012
                          IG: @mitchlikesbikes

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                            #14
                            Electrical help

                            i figured out that mishap. The o2sensor relay and the fuel pump relay were swapped on the bracket. However, that was not the root of the problem obviously.

                            ****87 325e, 2.7eta*****

                            What i know:

                            jumping the fuel pump relay does prime the fuel pump from pin 20 at the DME and 30-87 at the relay(pump is operational)
                            Pin 18 does not receive power on the DME (35 does)
                            all grounds pins to the DME have continuity to body
                            power does reach the coil
                            the coil reads the correct(ish) ohms to respective terminals
                            (15&1=.5) (15&4=5400)

                            What I am not sure of:
                            I though that pin 18 receives power from the fuseable link battery line via the main relay (pin 87)
                            however, there are two pin 97 and neither of them lead back to to the firewall from what i can see.

                            What is the path of power for pin 18 to the DME? I believe pin 18 is the same on both wiring harnesses. correct me if i am wrong.

                            I know i have to figure out the lack of power to pin 18 to proceed, though i am stuck here for the moment.

                            any help is much appreciated, i know there are some e30 electrical wizards who read these posts for fun it seems; granting electrical wishes to unsuspecting e30 owners.

                            I am really trying to have my e30 ready for The Vintage in may and I am starting to worry. I already paid for the hotel.
                            Last edited by MCreally?; 12-29-2017, 10:14 AM.

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                              #15
                              it sounds like you're overthinking this. if it ran before you pulled the engine and now it doesn't run you probably forgot something mindless that is preventing it from starting. unless you used a different and untested engine harness or DME you should not have anything going on that is this involved.

                              have you tested the crank sensor, cam sensor, etc on the new engine? is it even a new engine or did you pull the old one and just put it back in? you're not giving anyone enough information to help you diagnose it via the internet.

                              also, if you're worried that it's going to take you until may to diagnose a no start on an eta you should just drop it off at a shop and let them get it taken care of for you

                              1989 Coupe build thread: http://www.r3vlimited.com/board/showthread.php?t=312012
                              IG: @mitchlikesbikes

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