Guest 94vtecmn Posted January 5, 2006 Share Posted January 5, 2006 Ok, here's the story. Started the Pathfinder the other day, ran for about 5 seconds and died, as if I turned the key off. After checking a few things, the fuel pump fuse is blown. Only having a 20amp fuse left, (Fuel pump is a 10amp, I know, mistake) I stick that in there, and it fires right back up! Runs for about 30 seconds, and dies. This time, no blown fuse. Oooops. So I start with the obvious, fuel pump. Get that out, test it, and it spins just fine on 12v. Check the wire harness for current, no current coming to the fuel pump pin. There is power there for the low fuel and fuel gauge, and they seem to be working fine. So I hot wire the fuel pump with a lead directly from the battery with a 10amp fuse, fuel pump spins just fine! Put the key in, turn it over, doesn't fire a lick. So to make sure I got spark, I pour a little bit of gas down the intake, fires right up for about 2 seconds, and dies, as expected. So, I have spark, the fuel pump is running, but it won't start on its own. Now, what I believe is there is a return signal needed for something from the fuel pump, and thats not happening. My hot wire job consists of grounding the black lead of the fuel pump housing, and the 12v goes directly to the Blue wire. There is a White wire coming out of the fuel pump housing, that inside is a black wire. Do I need to give that a 12v current, similar to a power antenna lead from a car stereo to turn on the fuel injectors or something? If so, where does that need to go? Am I on the right path of patching this thing together? Any help and suggestions greatly appreciated. This is my winter beater and I don't plan on spending anything if I can cheat it back to running condition. Link to comment Share on other sites More sharing options...
Guest 94vtecmn Posted January 10, 2006 Share Posted January 10, 2006 I'm pretty sure its related to the fuel injectors not getting the "green light" to pump fuel. Can anyone provide me a wiring diagram, or a point to test to see if they are pulsing??? Link to comment Share on other sites More sharing options...
Simon Posted January 10, 2006 Share Posted January 10, 2006 (edited) My advice would be to change out the sending unit, rather than messing around with wiring near fuel. Dowser recently had a fire in his tank due to bad wiring. Mine did the same thing a while back (blowing fuses), but took out my fuel pump in the process. Edited January 10, 2006 by Simon Link to comment Share on other sites More sharing options...
Guest 94vtecmn Posted January 10, 2006 Share Posted January 10, 2006 Sending unit is located where? In the fuel pump assembly or under hood? Link to comment Share on other sites More sharing options...
Simon Posted January 11, 2006 Share Posted January 11, 2006 Sending unit is the part where the wiring is attached, and the fuel lines run through. It's on top of the fuel tank. It's the part the fuel pump is attached to. Upon re-reading your post.....I have to ask......where did you check the wiring? In the back by the tank? Did you check it on the sending unit? Or the other side of the harness? If you're lacking power at the harness, the sending unit is probably okay, and your issue would be in the wiring somewhere. I'd still try to find the problem, and fix it properly, as opposed to running wires straight from the battery. Link to comment Share on other sites More sharing options...
Guest 94vtecmn Posted January 11, 2006 Share Posted January 11, 2006 There was no current at the wiring harness, that's why I "hot wired" the fuel pump to see if I could get it going that way. Obviously there is a return signal that needs to go to something else. I should see if there is signal coming out of the sending unit, I don't remember if I did that, but I know the fuel pump works. If I knew where the sending unit was sending the "The fuel pump is working" signal, I'm sure I could get the injectors to pulse. Thanks for the help. Link to comment Share on other sites More sharing options...
88pathoffroad Posted January 12, 2006 Share Posted January 12, 2006 KISS... Do you have fuel pressure AFTER the filter? Link to comment Share on other sites More sharing options...
Guest 94vtecmn Posted January 12, 2006 Share Posted January 12, 2006 Not sure, where is the fuel filter located so I can check that...... Link to comment Share on other sites More sharing options...
Simon Posted January 12, 2006 Share Posted January 12, 2006 (edited) Under the hood....passenger side . Little canister with a fuel line going in the bottom, and coming out the top. Can't miss it. Edited January 12, 2006 by Simon Link to comment Share on other sites More sharing options...
Guest 94vtecmn Posted January 12, 2006 Share Posted January 12, 2006 Oh duh, I've seen that. Thanks for the suggestion...... Link to comment Share on other sites More sharing options...
SkinnyPedal Posted February 23, 2007 Share Posted February 23, 2007 Well sorry to revive an old thread, but this guy has EXACTLY the same problem I do. Unfortunately this thread kinda died off with no resolution posted. Anybody have any additional ideas? Link to comment Share on other sites More sharing options...
meangreenmachine Posted February 24, 2007 Share Posted February 24, 2007 If you hot wire the fuel pump and you are sure you have spark then you need to check for injector pulse. An easy way to do this is to disconnect one injector (if you have a noid light plug it in and crank it the light should flash if there is signal.) or you can use a test light. one side should have power all the time (with the key in the run position) and the other side should ground while cranking (the light may flicker or light up dimly this is normal. If you have constant power but no ground you have something wrong on the control side like an ignition module (or whatever other electronic device fires the injectors maybe the ecu) if you have ground and no power you have a problem with the feed side of the circuit (relay, fuse or open wire) Hope this helps and happy hunting! By the way is there anything in common with the fuel pump and injectors such as a relay or ecu some ecu's control the injectors and provide a fuel pump on signal (usually to a relay) Link to comment Share on other sites More sharing options...
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