roy Posted November 27, 2012 Share Posted November 27, 2012 Hi guys, Roy here from Malaysia. Nice to find a forum with the WD21's. If there are more forums, do share links with me. Well, i'm having a problem with the low fuel warning indicator. I checked the harness that goes to the instrument cluster & noted that there were 5 wires. I grounded the purple/yellow one & upon turning the ignition, the indicator worked. Then i realised that the harness from the fuel sender unit has only 4 wires. Which one is the low fuel warning indicator? I tried swapping the pins & none made the warning light go off when the vehicle is started. The whitish wire stalled the engine, i assume this is the fuel pump wire. Also, note that there is no pin in the position to connect to the purple/yellow wire that i grounded (on the harness that goes to the instrument cluster) Could this be a manufacturing defect as i never had the fuel warning light before? Please advice guys. Thanks Roy Link to comment Share on other sites More sharing options...
silverton Posted November 27, 2012 Share Posted November 27, 2012 Have you pulled the fuel pump assembly to see if the sensor is even there? I wonder if it could be dirty? Does the light come on normally with Key On Engine Off? It's one of the "dummy" lights that's supposed to come on. Link to comment Share on other sites More sharing options...
Trogdor636 Posted November 27, 2012 Share Posted November 27, 2012 Does the light come on normally with Key On Engine Off? It's one of the "dummy" lights that's supposed to come on. Are you sure about that? I've never seen my low fuel light so I asked my buddy if his came on with the key because his low fuel light works. His light doesn't come on with the key. Link to comment Share on other sites More sharing options...
silverton Posted November 27, 2012 Share Posted November 27, 2012 (edited) The low fuel light comes on in both my pathfinder and my 200sx with key on engine off. look in your owners manual, if you have one, it'll show that it's one that comes on as a light check, like the CEL. I know for sure it comes on cause i think it's dumb that it comes on with the key on, but doesn't come on when I putter to a stop... Edited November 27, 2012 by silverton Link to comment Share on other sites More sharing options...
Trogdor636 Posted November 27, 2012 Share Posted November 27, 2012 look in your owners manual, if you have one, it'll show that it's one that comes on as a light check, like the CEL. Maybe it changed in 95? Here are the lights that come on according to my owners manual. OP, have you ran out of gas? Reason I ask, is I recently replaced my fuel tank (old one had a leak) and I ran it down and never saw my low fuel warning. I swore I had to be out of gas, as I had been driving around for miles with it on E. When I lowered my old tank, it still easily had about 2 gallons left! I have a small 3 gallon gas jug I plan on filling and then driving until I either see the light, or run out of gas. Link to comment Share on other sites More sharing options...
Slartibartfast Posted November 28, 2012 Share Posted November 28, 2012 I suspect that the low fuel light is tied into the fuel gauge, and therefore doesn't have its own wire from the tank. My gas needle moves around a bit, and the one time I've had it low enough on fuel for the indicator to come on, it wasn't constant. It came on one day, went off the next day, came on again later... then the fuel level got so low that it sucked the crud out of the bottom of the tank and gummed up the pump. My fuel light doesn't come on with the other idiot lights. I've seen it come on, so I know the bulb is good... but it hasn't shown up since I ran it out of gas. Link to comment Share on other sites More sharing options...
RF600 Posted November 28, 2012 Share Posted November 28, 2012 Something to think about. Fuel lubes and cools the pump. So I don't let my fuel gauge to get below 1/4 tank. Things happen and we all can't keep fuel in the tank. 1 Link to comment Share on other sites More sharing options...
Tungsten Posted November 28, 2012 Share Posted November 28, 2012 My low fuel gauge never comes on with the bulb check but I was close to running out of gas once and it has come on. Not that I care for it anyway as I always try to re-fill at 1/4 tank mark for the reason mentioned above. Link to comment Share on other sites More sharing options...
Towncivilian Posted November 28, 2012 Share Posted November 28, 2012 (edited) The fuel level sending unit could be affected by sulfur build up, leading to an inaccurate fuel gauge. I don't see why it couldn't affect the low fuel indicator as well. Chevron Techron has been reported to clean sulfur build up and fix inaccurate or stuck fuel gauges. Try the 20oz bottle in your next tank. Even if it doesn't fix the malfunctioning indicator, it will effectively clean your fuel system since it contains PEA (polyether amines) which clean without leaving deposits of its own behind like solvent based cleaners. On another note, the low fuel indicator does not illuminate with ignition set to ON on R50s. Edited November 28, 2012 by Towncivilian Link to comment Share on other sites More sharing options...
silverton Posted November 28, 2012 Share Posted November 28, 2012 Well, that just friggin blows my mind. I swear it comes on in my WD21, but I haven't driven it in almost 8 months, so who knows. I know for CERTAIN that it comes on in my S12 with key on. One thing I know for sure since I've had two pumps in and out of my truck very recently, is that the low fuel light sensor is different from the fuel level gauge float. Link to comment Share on other sites More sharing options...
roy Posted November 29, 2012 Author Share Posted November 29, 2012 Have you pulled the fuel pump assembly to see if the sensor is even there? I wonder if it could be dirty? Does the light come on normally with Key On Engine Off? It's one of the "dummy" lights that's supposed to come on. No, i have not pulled the fuel pump assembly to see the sensor. I was thinking of troubleshooting the wiring first. It would be great if someone knows the colour codes of the wires from the sender. (What colour represents what function). Maybe it changed in 95? Here are the lights that come on according to my owners manual. OP, have you ran out of gas? Reason I ask, is I recently replaced my fuel tank (old one had a leak) and I ran it down and never saw my low fuel warning. I swore I had to be out of gas, as I had been driving around for miles with it on E. When I lowered my old tank, it still easily had about 2 gallons left! I have a small 3 gallon gas jug I plan on filling and then driving until I either see the light, or run out of gas. Maybe it did change in '95 onwards. But if so, how do i check if it works? I have driven till the gauge is really low. i.e Below the redline & the light never came on. I dont intend to try this again as i believe driving till the fuel in the tank is so low flushes the gunk & grime up the fuel pump. I suspect that the low fuel light is tied into the fuel gauge, and therefore doesn't have its own wire from the tank. My gas needle moves around a bit, and the one time I've had it low enough on fuel for the indicator to come on, it wasn't constant. It came on one day, went off the next day, came on again later... then the fuel level got so low that it sucked the crud out of the bottom of the tank and gummed up the pump. My fuel light doesn't come on with the other idiot lights. I've seen it come on, so I know the bulb is good... but it hasn't shown up since I ran it out of gas. Can someone confirm that the sensor is tied to the fuel gauge? I find it makes no sense that the low fuel indicator wire has no pin connected to it. How else will the indicator work. Link to comment Share on other sites More sharing options...
silverton Posted November 29, 2012 Share Posted November 29, 2012 I can confirm that the low fuel light sensor is separate from the pump float for the fuel gauge. I've seen it on two different pumps, one from a 95 and one from an 87, so it must have its own wire. If you pull the pump, you'll be able to trace the wire from the low fuel sensor to the cover where the wiring loom goes through I'm sure. Link to comment Share on other sites More sharing options...
roy Posted December 4, 2012 Author Share Posted December 4, 2012 Thanks to all. I took the advice here & opened up the fuel sending unit. To my amazement, no low fuel warning sensor. Hence, the absence of the wire i was talking about. Guess i have to wait till the sender breaks down to replace it with a unit with sensor. Unless the sensor can be installed seperately. Roy. Link to comment Share on other sites More sharing options...
Precise1 Posted December 4, 2012 Share Posted December 4, 2012 Nah, just fill it up at 1/4 tank and keep 5 gallons on the back... B Link to comment Share on other sites More sharing options...
Trogdor636 Posted December 4, 2012 Share Posted December 4, 2012 Perhaps Nissan didn't make it a option for your country? That's odd. My gauge has been way below the red line (when I was ready to swap with my other tank so it didn't weigh a ton) but like I said there was still at least 2 gallons. My fuel gauge is just horribly off. Link to comment Share on other sites More sharing options...
WxChaser Posted December 4, 2012 Share Posted December 4, 2012 Anyone know if a 93 WD21 SE comes with an indicator light, and where I could find that light? Can't seem to spot it on the dash, but I may not be looking hard enough. Or is the indicator down where the ABS light is? Let me know. I may not have the sensor built in either, who knows? I typically don't run it low, but there have been a couple of times. Link to comment Share on other sites More sharing options...
Alkorahil Posted December 4, 2012 Share Posted December 4, 2012 (edited) For North American WD21 and R50..... They should all have the low fuel light......it just comes on when you are bascially out of fuel. IF in proper working order, it supposed to come on at 3 gallons left of total fuel in the fuel tank and about 2.5 gallons usable fuel that the pump can suck up. That low of a level of fuel on a WD21 will be at about 3mm below the lowest white mark on the fuel gauge. (if it is working properly) Most of us fuel up before that point! To make yours go on and see that it does indeed work...run your tank down to the white line, and then put it on a steep incline, the guage will drop way low and the light will come on. As noted, on the WD21 it does not cycle when you turn the key on...I dont know why. I am unsure on the R50. I would note that on our vehicles....they are old and have lots of particulates that have collected in the fuel tanks and on the sender units in the fuel tanks over the years. Edited December 4, 2012 by Alkorahil Link to comment Share on other sites More sharing options...
Precise1 Posted December 4, 2012 Share Posted December 4, 2012 IF in proper working order, it supposed to come on at 3 gallons left of total fuel in the fuel tank and about 2.5 gallons usable fuel that the pump can suck up.That low of a level of fuel on a WD21 will be at about 3mm below the lowest white mark on the fuel gauge. Ok, that's good to know. I personally fill up at 1/4 tank unless I'm on a highway road trip but even filling up when the gauge is on E, I have never put in more than 17 gallons or so. The 3mm below E explains that now. I see no point in letting it get that low unless it is an emergency regardless. I just filled up the R50 with 14 gallons/$50 of fuel. B Link to comment Share on other sites More sharing options...
Trogdor636 Posted December 5, 2012 Share Posted December 5, 2012 Anyone know if a 93 WD21 SE comes with an indicator light, and where I could find that light? Can't seem to spot it on the dash, but I may not be looking hard enough. Or is the indicator down where the ABS light is? Let me know. I may not have the sensor built in either, who knows? I typically don't run it low, but there have been a couple of times. I'll ask my buddy if nobody else chimes in. He has a 93 and he's seen the dash light. Link to comment Share on other sites More sharing options...
WxChaser Posted December 5, 2012 Share Posted December 5, 2012 Thanks all. Have never seen it, but that may be due to the fact that I never let it reach the E line.. Really close at times, but never on it. Considering changing to a 90 Pathy dash that has the light visible next to the fuel gauge. It would just be nice to have because I storm chase with this vehicle, and knowing that I'd roughly have "X" amount of fuel left would be good. Link to comment Share on other sites More sharing options...
silverton Posted December 5, 2012 Share Posted December 5, 2012 It's just a dummy light for the blondes that need a light to come on instead of a sweeping needle to the ever foreboding E on the fuel gauge not sure what the whole hub bub is about... Link to comment Share on other sites More sharing options...
WxChaser Posted December 6, 2012 Share Posted December 6, 2012 Well, one of these days I'll carry a 5 gallon tank and see how low I can go. That's why I was looking for that light. I've only had a light in one of my vehicles, (Ive owned 4) so it's not like I need it. It would just be nice to say "Oh, the light's on, that means I have "x" gallon(s) left." Link to comment Share on other sites More sharing options...
roy Posted January 4, 2013 Author Share Posted January 4, 2013 I guess i have learned to live with this by filling up the tank on regular intervals.. This will go on till my sender unit fails & i have to replace one. Will ensure that i get the right one with fuel level sensor. Link to comment Share on other sites More sharing options...
Inyourface1650 Posted January 5, 2013 Share Posted January 5, 2013 Hehe, I can tell you either mine doesn't work or I don't have one - the GF ran my '94 out of gas on New Years Morning (1am on the side of the highway, fun!) Link to comment Share on other sites More sharing options...
ef9 Posted February 19, 2014 Share Posted February 19, 2014 Sorry to resurrect this old thread from the dead...... I am having the exact same problem with my '95 D21. The fuel pump wires are blk(-) and wht/blu(+). The fuel level sender wires are blk(-) and yel/grn(+). The low-fuel warning light uses the same black wire as the fuel level sender (but is separate from the fuel pump), blk(-) and yel/pur(+). My fuel gauge and low warning light both don't work. Something is wrong with my in-tank unit. Link to comment Share on other sites More sharing options...
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