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A no start/dead fuel pump saga

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    A no start/dead fuel pump saga

    So when I bought the no rust 323 from Chad, he had jury rigged a wire from the radio to run the fuel pump, since it wouldn't start sometimes. Car made it home 250 miles fine but I didn't want to leave it like that. Plus in the process the gas gauge no longer worked. And the interior light did not work when you opened the doors.

    First thing I looked at was the mickey mouse air intake, with the VAF hanging off the air pipe at an angle and jammed against the distributor cap, and no retaining clip on the VAF cable, which was halfway unplugged. Sure enough, had a 08 code set, bad VAF signal. Put all stock parts back from another car and disconnected the jumper - no more code, but no start, no pump.

    Had good power at the relays, but at the pump jumper harness under the seat all the wires had random voltage which was different every time I measured. One of those wires isn't even connected to anything, since it is for low fuel warning, which this car doesn't have.

    So I took the seats and carpet out to follow the harness, and found a plug in the harness which is not on the '91 diagram I have - car is '93. This is right where the left sill meets the bulkhead below the rear seat, at the bottom of the B post. The plug cleverly lies right on the floor under the carpet. Sometime in the past, somebody had "fixed" the pump power wire by removing it from the plug and splicing it with male/female slide connectors, badly crimped; then they put it all back making sure the splice was directly on the floor, to pick up any trace of salt water there might be. As soon as I touched this mess, the pump wire and the gauge wires fell apart. The plug was a mass of green powder. Every pin and wire was green powder. I had to cut out the plug and splice pieces in to all the wires there, very difficult since all the wires were corroded. Cut them all back a couple of inches and Very carefully scraped all the strands clean so I could solder them. There are a bunch of wires there that don't go through the plug, and I didn't have time to figure out what they are all for, but the plug had pump, gauge & ground, Low fuel light, brakelights, taillights, and two for the door switches for the interior lights which also trigger the auto belts.

    I think the original problem was the VAF cable, but in crawling around to check the pump random feet made these wires fall apart, so anybody with problems on these circuits might want to look there, or better, look there before you have trouble and get that plug off the floor! I also don't know which cars have the plug that is not shown in the '91 diagram. And remember that this is a car with NO RUST that rarely ever saw salt or snow, so most of them may be much worse.

    So after working all night, I had power at the pump harness, and the interior lights worked, but no gauge and no pump run! Took the tank unit out and the gauge sender is DOA, and the pump doesn't fit in the brackets right (too big) and is about to fall off. Put the tank unit from the other car in and have gauge but no pump!

    Examined the wire where the jumper had been and found that the GD Scotchlok connector - too small size - had cut all but two strands of the pump power wire. Spliced that, still no pump, unless I held the connector in my hand - hard to drive that way. Looked inside the harness plug at the pump jumper harness, and saw that the power pin was dark instead of silvery, that usually means it has been hot and is oxidised so doesn't make contact. It probably started with the original problem that they were working on when they spliced the power wire under the carpet, likely a dead shorted pump. So, I bent the harness plug pin into a gentle "S" bend and put OxGard on it, and that made contact and did the trick.

    So that is about 5 things in the pump circuit that could cause intermittent or permanent pump death at any moment, ALL of them due to bad workmanship over the years.

    Moral of the story is FIND the PROBLEM and FIX IT RIGHT or you WILL be plagued forever with weird crap! (at least, I HOPE it is YOU and NOT ME!)

    FRM

    #2
    christ, the possible issues i have to chase down is getting longer...going through the same thing right now. i've tried three different VAFs and no change yet, so now i am thinking i have to chase down a possible fuel pump power issue.
    1993 Mazda 323 DX, 5spd 1.6SOHC, just trying to fix it to sell an honest to goodness car.
    2004 Infiniti G35 6MT Coupe, the bruiser.
    1989 Volvo 240GL Wagon, the new dialy as soon as that pesky Mazda is gone.
    2011 Kia Forte-5 SX, the wife's car.

    Comment


      #3
      Hard to know with so much other stuff going on but the work you did on the vaf may have affected the fuel pump. There are two wires in that plug that activate the fuel pump, assuming you have 7 wires on that plug. If they got broken or weren't seated properly, it could cause the problem you describe.
      Last edited by 1st Gen; 10-01-2011, 09:20 PM.
      1991 Protege LX with GTX swap, DD
      1990 4WD Protege with GTX swap, Project/garage decoration
      2006 Mazda 3 with 2.3, Her car
      1980 Ford F100 Short bed with 300ci 6 cylinder, work truck/home for moss

      Comment


        #4
        Are you talking about the harness plug itself? I have noticed I get flucuations when I mess with it. It was driving fine for a good while and now its just crappy.
        1993 Mazda 323 DX, 5spd 1.6SOHC, just trying to fix it to sell an honest to goodness car.
        2004 Infiniti G35 6MT Coupe, the bruiser.
        1989 Volvo 240GL Wagon, the new dialy as soon as that pesky Mazda is gone.
        2011 Kia Forte-5 SX, the wife's car.

        Comment


          #5
          1991 Protege LX with GTX swap, DD
          1990 4WD Protege with GTX swap, Project/garage decoration
          2006 Mazda 3 with 2.3, Her car
          1980 Ford F100 Short bed with 300ci 6 cylinder, work truck/home for moss

          Comment


            #6
            Well,
            You haven't said what car you have
            What eng/trans/air or no.
            Cruise might matter too - much very different wiring.
            Stock or modded
            Codes or no
            What your problem was/is
            What you did, except random changing of VAF - for what reason?
            Do you have and know how to use: wiring diagram, test lamp, VOM?
            Finally,. do you want help or are you just bitchin'? (might be understandable with such problem's!)

            FRM

            Comment


              #7
              Originally posted by gofanu View Post
              Well,
              You haven't said what car you have
              What eng/trans/air or no.
              Cruise might matter too - much very different wiring.
              Stock or modded
              Codes or no
              What your problem was/is
              What you did, except random changing of VAF - for what reason?
              Do you have and know how to use: wiring diagram, test lamp, VOM?
              Finally,. do you want help or are you just bitchin'? (might be understandable with such problem's!)

              FRM
              I apologize for the lack of details, my post was defintely more of a rant and I actually sent the OP a PM regarding the issue more specifically. To answer some questions I updated my signature to include my car info. I didn't set one up initially because I was only using the forum for trouble shooting when I was working on the car these last few months, so I was doing a lot more browsing and searching than I was posting. Now I have come into an issue that has me a little perplexed and frustrated and through searching and part swapping I feel like I may be suffering from a fuel pump power issue moreso than a bad VAF.

              To give you more details to my story here is how I got to where I am (this gets long):

              I took ownership of the car from my father back in hot-sticky July-2011. The car sat for the better part of over 1-yr, put in a new battery and it fired right up and actually sounded pretty healthy. Being as how it sat for awhile the car wasn't driving the best, so I attacked the brakes first and that fixed a lot of the driving problems. That meant I could drive it on a regular basis and discover the other demons lurking around. I tried to fix the A/C on the cheap, but I wasn't as successful or lucky as I hoped with a 134 converted compressor from a junkyard car. So then I focused my attention on the 203+k mile original clutch and this was where the trouble started. Basically the clutch job didn’t go that easily, due to misc. bolts in misc locations not cooperating, so I decided it was just going to be easier to drop the whole front sub-frame with the engine and trans attached (mind you I was doing this without any service manuals or online guides). While in there I replaced the clutch, flywheel, rear main seal and redid/replaced the oil pan seals, some fresh bushings on the shifter linkage, new lower ball joints and good scrubbing of everything I could get my hands on. Assembly back into the car was a breeze by this point (still without manual assistance, but I did hunt down some torque numbers) and everything went back together pretty well. I topped off all the fluids and it started up on the first cranks, but proceeded to run like crap.

              At this point I knew something I did early was causing problems. Being as how most of the cars I have worked on were Nissans and Nissan most exclusively uses true MAFS, so during tear down I made the common mistake of thinking the 2 screws by the VAF plug held the MAF and of course I was met with the separating pins. I made mention of this to my dad and he mentioned he made the same mistake during his ownership, so I went out on the hunt for a new junkyard sourced VAF. Came back with one, hooked it up and all was good again. The car was running pretty well. The idle was a little high but everything seemed to be operating smoothly. I drove it for a week and finally got to E on my first tank since I had the car (this was early September now).

              I did have one hiccup shortly after this where it would stumble with more than half throttle demand, but it was right after I gave the car a thoroughly cleaning to include the fuel cap area because it was caked in black grime. Being as how it was practically on E, I figured I got a little water in the tank and limped it to the nearest gas station. I filled up the tank and viola, all was right again, this was on a Sunday not long ago. I drove the car to work Monday thru Wednesday no issue there or back, but then I tried to use it shortly after I got home Wednesday evening to go meet up with some friends and that is where things went bad. I got 2 intersections away from my house when all of a sudden it was having the throttle cut off issue again, but this time it was getting worse and was idling rough too. I tried to limp it home, but it left me stranded and I managed to get it to a gas station that was within walking distance to home. I went back to it later at night and I was able to limp it home. This was roughly 90-miles after the last fill up.

              After speaking to my father again, he said this sounded like a problem he had during his ownership right before he parked it. After about 30-40 mins into his work commute it would stumble and die on him. He’d let it sit and cool off and it would come right back. That combined with him getting a newer truck was the reason it got parked. Up until the point above, I was only doing short to/from work commutes of about 20-mins each way or even out to lunch. He felt like it was related to the fuel system and he even had a new fuel pressure regulator he meant to install, but never did. I proceeded to replace it in addition to a new fuel filter and still no change. I tried new plugs and wires, no change. Pull codes and got an 08 and a 17. I attributed the 17 to the issues related to the VAF and 08 code, figuring the bad reading was causing a bad mix. So this put me back on the path of a bad VAF. I replaced that VAF with another one this past weekend and still no change.

              So with all of that I have concluded a few things. First I did mess up my first/original VAF with the common 2-screw trap. Second the replacement VAF might still be good as I have done nothing internal to that. Third, now that the other replacement VAF isn’t correcting anything I can only assume based on searching I may be having a fuel pump run issue. Once I put the new VAF in after an ecu reset, I was prompted with a beautiful idle and a check engine light, but once the CEL went away after 10 or so seconds it went to a rough idle. This prompted me to play with the VAF plug a little and it smoothed out again, but it was idling high and then I had the same throttle stumble as soon as I applied any throttle pressure. So that is exactly where I am at this moment.

              Here is a short list of what I have serviced since July-2011:
              New clutch kit and flywheel
              New rear main seal
              New oil pan seals
              New oil and filter
              New rad fluid
              New trans fluid
              New lower ball joints
              New A/C dryer/receiver
              New 134 adapter fittings
              Junkyard special on its way out AC compressor
              New a/c belt
              New alternator belt
              New fuel pressure regulator
              New fuel filter
              New plugs and wires
              New front brakes and new brake/clutch fluid.
              “Broke” first VAF, replaced with another and then replaced that one with another with no problem correction.

              My best guess is to first see if the IACV is a culprit in any of this and if not I will proceed to diagnose my wiring from the VAF back to the pump. I picked up a VAF pig-tail Sunday while at the yard helping out my mom pick some parts for my dad’s truck. I will use the pig-tail to compare against mine and see if I find anything significantly different. I will probably try to clean up some grounds too while I am at it. My last resort will be to pull up the carpet and inspect the wiring leading to the pumps to see if I find anything there as well.
              1993 Mazda 323 DX, 5spd 1.6SOHC, just trying to fix it to sell an honest to goodness car.
              2004 Infiniti G35 6MT Coupe, the bruiser.
              1989 Volvo 240GL Wagon, the new dialy as soon as that pesky Mazda is gone.
              2011 Kia Forte-5 SX, the wife's car.

              Comment


                #8
                Funny, I am the OP, I think, but no PM or notification anywhere.

                Time to stop guessing and measure stuff.
                You can tee in a fuel pressure gauge between the filter and the fuel rail and read pressure in the car if all else fails.
                Get a Haynes or otherwise find the wiring diagrams or you will go crazy.

                All this stuff may be bad ground connections, at numerous places; see my comments at beginning of my FP diag. notes below.

                People have found corroded wires, especially around the battery area. (these get wriggled when you fool with the VAF cable) Since your problem may have started with all that fiddling, this is a good place to examine minutely.

                Failing that, the dead stop no run is most commonly a failing distributor, but that should show up as an 02 code. But, it seems that sometimes it won't set a code if the intermittent problem hasn't been present long enough and is not present when you check. Cooling off "fixes" it until it gets really bad. Pull coil wire from cap when it dies and crank to see if there is spark to ground. One of mine did this randomly at increasing frequency for two years before it finally died completely.

                Death after running for a few (5-30) miles could be a problem with the fuel venting craziness by the LR wheel. I have not had this problem, and hope I never. Check by loosening gas cap.

                Bad/erratic idle is most commonly bad cap/rotor/wires, dirty throttle body or dirty IAC - free to clean!, or funky TPS.

                TPS can be checked with VOM; backprobe connectors with key ON not running. One terminal is 5V supply from ECU, one is ground, other is 0-5V output. Check supply to ground and to ground terminal - should be the same at near 5V, else bad ground.
                V between G & Output should vary smoothly as throttle is moved from closed to open and back, very slowly. Any drops or peaks are bad, most commonly near idle and at road cruise, ie about 30% open. I have successfully opened these up and cleaned with contact cleaner.

                My notes from fuel pump diagnostics:
                *************
                At diagnosis box underhood (labels show both wire colours and letter designations):

                B = GND = ground, aka B- {other system grounds are B, B/O, B/LG, possibly more colours}

                W/R = +B = 12V through Fuel Inj fuse >W/G> main FI relay (underhood) >>>W/R>>> So, 12V here (key ON) means all that is OK in the first half of the fuel system electrical supply. If not, check the "15A Engine" fuse in the interior fusebox - it supplies control power for the main FI relay. This circuit also supplies power to the ECM and distributor, so if it is dead there will be no sparkles and maybe a 02 code, maybe others. Open of the dist B/LG grnd would also give a code 02 (no Ne) signal & no spark.
                {I check +B to battery --, then to both GND connections in diag box, then to B/LG wire in distributor connector. All should give the same voltage; if not, then there is a bad grnd someplace}

                {Dist: W/R = B+; B/LG = B- gnd; W = to ECM signal; Y/L (If present)= to ECM tach signal }

                LG = FP = control coil output (grnd) from circuit opening (fuel pump) relay (in car by ECM). So the FP>jump>GND checks everything in thr FP circuit except bypasses MAF run signal and pump crank to start signal from ECU Also goes to MAF (switch for eng running signal????) Yes, per Haynes 12-25, LG is switched to B (gnd) in MAF when running.
                {This relay has two operating coils: one for starting = STA to E1 = 21 -43 ohms; one for operating B to Fc = 109-226 ohm. Above test checks operating coil, applying Battery power across STA-E1 checks start coil. B to Fp should be open with no power, or closed = 0 ohm with power across either coil. But the relay should not be operated for a long time with popwer across STA-E1 as it will overheat.
                At relay plug: B is W/R wire 12V, Fc is LG grnd to MAF, Fp is B/P 12v out to pump, STA is V (12V starting sig from ECM), E1 is B = grnd

                >>>Jumping W/R (battery) to B/P (pump) in the harness plug for the relay next to the ECM will bypass the relay completely and operate pump whenever key is ON. If there is power at B/P and the pump does not work, it is bad, or the B/P back to the pump is bad, or the grnd from the tank is bad.

                Y/L = IG -- = from igniter & coil & tach {Coil B+ is supplied direct from IGN switch via L = blue wire, which has a suppression capacitor in it via connectors and grounded via a B/O}

                B/G = TFA = to tank unit, fan relays, AC relay, ECU, Then After the DiagConn branch, goes to grnd through Water Thermoswitch. So jumping to ground bypasses this switch. This seems to be the two wire switch that causes all sorts of trouble, not the "water thermosensor", aka gauge resistance sender (gauge sensor has B/O wire). BUT It looks like the "Water Thermoswitch" may also come in a one wire version; it is just a switch, op temp unknown yet. Appears to switch B/G to ground, so it should be jumpable for tests or emergency.

                At the tank unit plug, B/P is pump power, B is pump grnd, Y is gauge, B/G is gauge grnd, but it is very goofy and runs all over the place, appearing finally to ground through one of the thermoswitches on the engine. And there is a W/R that appears to be different from the other W/R discussed above, comes from the instrument cluster - I think it is for a fuel level warning light that I do not have on any of my cars.

                I found 3 thermo gizmos on my 94 DX standard w/air. Front of head by ex manifold - one B/O wire (gauge); On Tstat housing, one B/G wire; in back of dist, looks like a rwo wire connector but I can't see what colour and it is v dificult to unplug - and it is the only thing I have to drive.

                90 B6 auto w/air does not have the two wire one behind the dist.
                92 B6 standard no air doesn't have it either (stuck in Mass)
                93 LX standard w/air has
                94 LX standard w/air has
                Spare EGT head has a swtch (missing) below the tstat housing from the front, One (broken off) on the Tstat housing, & a two wire one behind the dist in the head.

                W/Y = MEN from ECU
                W/B = FEN """"""""
                LG/Y = TEN """"""""
                ***************

                Finally, if you get it fixed and it isn't rusty, keep the Mazda - it is the best car you will EVER have!
                I'd buy it but I have too many and no money.

                FRM

                Comment


                  #9
                  So I checked out the harness plug into the VAF and I quickly noticed that two pins in the plug were pushed back. I set them back into place and viola! Problem solved!!!!!! I am just glad I got lucky and found the problem in the first place I looked. Now I am going to get that idle to come down a little bit. Thanks for pointing me in the right direction!
                  1993 Mazda 323 DX, 5spd 1.6SOHC, just trying to fix it to sell an honest to goodness car.
                  2004 Infiniti G35 6MT Coupe, the bruiser.
                  1989 Volvo 240GL Wagon, the new dialy as soon as that pesky Mazda is gone.
                  2011 Kia Forte-5 SX, the wife's car.

                  Comment


                    #10
                    so question to OP. Would the fuel pump work if you you jumped it in the diagnostic box? or was the only way to get it to work was to run another power wire? (like from ignition). I have a chiltons manual in storage and plan on digging it out sometime next week to go through wire diagrams.

                    Comment


                      #11
                      Originally posted by '91protege View Post
                      so question to OP. Would the fuel pump work if you you jumped it in the diagnostic box? or was the only way to get it to work was to run another power wire? (like from ignition). I have a chiltons manual in storage and plan on digging it out sometime next week to go through wire diagrams.
                      If you read the story, you will see that I had both situations. Not an uncommon thing, especially if people have been fooling with it. ANY non native wires are highly suspect.
                      You said you had a blown "main fuse", Q is why? And, are any other fuses blown, esp the "FI" or in car "engine"" ones?
                      People have found chafed/shorted/broken wires, especially around the battery area.

                      Most of what you need is in my notes, but certainly wiring diagrams are a GOOD THING.

                      FRM

                      Comment

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