Nightmare_Fairlady Posted December 13, 2013 Share Posted December 13, 2013 So to start, my fuel pump went out a day after I picked up the car (go figure). Now she's been sitting for almost a week and a half because I cant figure out what is wrong with her. I bought a new fuel pump from work, put it in, just to find out the wires to the pump are bad. So instead of running new wires all the way back I just ran the pump through a switch that I hid for security reasons. Long story short, I hit the switch, fuel pump fires up, I can hear it inside the car, but she wont stay running. The Z will start for a second or two and then die again. Am I not getting enough pressure? Or do the original wires that go to the pump have to be plugged in because of a sensor or something? Please help and thank you in advance. P.S. I miss my Fairlady... Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 13, 2013 Share Posted December 13, 2013 Here's your original post on the subject, and some replies, in case you couldn't find it - http://forums.hybridz.org/topic/115965-suitable-280z-fuel-pump/?do=findComment&comment=1087600 - Post #15 is you. You might still have the pump wired incorrectly. Measure fuel pressure while starting and when it dies. The problem may not be the pump at all. This is a vague description of what's happening - "I hit the switch, fuel pump fires up, I can hear it inside the car, but she wont stay running." Which switch, ignition or your new one? Check the AFM fuel pump contact, maybe your new wires aren't doing anything. http://www.nicoclub.com/FSM/ Quote Link to comment Share on other sites More sharing options...
9rider Posted December 13, 2013 Share Posted December 13, 2013 AFM contact point would pretty much do the same thing. Fire car up and good for 2 seconds. AFM is in side the black plastic box of AFM. Both fuel injection service manual and FSM have diagrams. Quote Link to comment Share on other sites More sharing options...
Nightmare_Fairlady Posted December 14, 2013 Author Share Posted December 14, 2013 When I say I hit the switch, I'm referring to the switch that I wired to my fuel pump. I turn on the ignition, turn on my switch, and I can hear the pump from in the car. I know the pump is working because I pulled the line off the fuel rail after the filter, hit the switch, and it sprayed fuel into my bucket. Let me back up a few steps.. I was sitting at a light, started to go and the whole car jolted, died, and wouldn't start again, thus ending with me pushing the car a few blocks. Before I bought the new pump I put the old one straight to the battery, and nothing. When I put the new pump in is when I discovered that the original wiring was bad. That's why I ran the switch. I don't think the AFM, wiring, and pump could all go bad at the same time but hey, what do I know. I haven't measured the fuel pressure yet, (money I just don't have at the moment), and I know that's Z cars are very finicky when it comes to pressure. 36psi I believe. I was told by some guys at work to pinch off the return line on the FPR and if it ran a bit longer then that's what is bad. Do you guys think that could be a possibility? Thank you for your help Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 14, 2013 Share Posted December 14, 2013 You kind of have the "maybe I did too much at one time" problem. The engine ran with the wiring to the old fuel pump (for one day at least), assuming that it was a bad pump that caused it to stop running after one day. But now you have a new pump and modified wiring. Would have been more clear if you had installed the new pump with the old wiring, then fixed the wring afterward. But you are where you're at so the best you can do is run through the basics - confirm that you have spark, confirm that the injectors are firing, etc. Your bucket test shows fuel flow, but not pressure, so if you're not going to measure pressure all you have are the other things. Your question about what needs to be plugged in and what doesn't are all described in the FSM. Maybe your bad wiring shorted and took something else with it, like the ignition module or the ECU. Run through the basic tests in the Engine Fuel chapter and something will show up. "Have fuel, engine won't stay running" could be caused by all kinds of problems. And you forgot to identify year of car in this new thread. Quote Link to comment Share on other sites More sharing options...
Driftinrican Posted December 14, 2013 Share Posted December 14, 2013 You may want to check the condition of your fuel before the filter as well. I had a similar problem with my z. But mine has a few more Issues. But if the fuel is brown or reddish drop the tank and have it cleaned out professionally. From my experience they tend to rust if not driven often. Heck when I took mine down I found ten pounds of rust in it. So I had paid for a fuel pump when I didn't need one. Quote Link to comment Share on other sites More sharing options...
Nightmare_Fairlady Posted December 16, 2013 Author Share Posted December 16, 2013 Its a '76 280z, and yes I used the old wiring with the new pump, and got nothing. Then I put both the old and the new pumps straight to the battery, they both fired up. That's when I ran the new wires. Last night I decided, eh, what the hell, and put the old pump back in, went to try to start it and the battery didn't have enough juice. Its been sitting on a trickle charger all night so when I get off work ill see if that fixed it. I hope that maybe the new pump just didn't have enough pressure. The fuel is fresh as well, no rust in it anywhere. Trust me, I took a bath in it... Noob question but by FSM do you mean the Field Service Manual? I honestly don't know and I feel dumb for asking. But honestly, I would rather feel dumb for asking a question vs going without the information. Thank you Quote Link to comment Share on other sites More sharing options...
Nightmare_Fairlady Posted December 16, 2013 Author Share Posted December 16, 2013 Factory service manual... gah I feel dumb.. Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 16, 2013 Share Posted December 16, 2013 (edited) Before I bought the new pump I put the old one straight to the battery, and nothing. Then I put both the old and the new pumps straight to the battery, they both fired up. That's when I ran the new wires. Last night I decided, eh, what the hell, and put the old pump back in, went to try to start it and the battery didn't have enough juice..... You might have the "I've done so many things I can't remember exactly what I did" problem. Still, confirming the basics won't hurt. Engine Fuel chapter in the FSM. Get a multimeter. Your replacement pump should put out about 2.5 times the pressure the engine needs. Edited December 16, 2013 by NewZed Quote Link to comment Share on other sites More sharing options...
Pac_Man Posted December 17, 2013 Share Posted December 17, 2013 While you're messing with the fuel pump, I'd suggest adding a pre-pump in-line filter as well. Most people (myself included) opt for a 3/8 inlet and outlet filter such as the Fram G3. Use 7/16 line from the tank to the filter (trust me it works fine with the 3/8 inlet on the filter) and then 3/8 line from the filter to the pump. At least that's what I did. While it's possible that crap from the tank is causing the issue, it's not particularly likely in my opinion. That said, using an aftermarket pump means no inlet cone screen which is in the stock fuel pump. I added the G3 to make sure nothing happens in case my fuel tank is cruddy and causes issues with the pump. Quote Link to comment Share on other sites More sharing options...
Nightmare_Fairlady Posted December 17, 2013 Author Share Posted December 17, 2013 I put my old pump back in, and started to think... If my fuel pump relay is bad, would that kill the wires to the pump itself? That way, even though I'm running a switch to the pump, the computer reads that the relay is bad still, so in turn the computer could be reading that the pump isn't working and running a fail safe and killing the engine to prevent damage. I just ordered the relay from work and it will be here this afternoon. Its made by Standard Motor Products if that makes a difference. It said in the description that it was OE replacement so it should work. Gah, 5 o'clock cant come quick enough!! Quote Link to comment Share on other sites More sharing options...
superlen Posted December 18, 2013 Share Posted December 18, 2013 For your car, the ECU controls NO part of the circuit that operates the fuel pump. The fuel pump control is completely external using the relay and the AFM switch. (75-77). If you're pump is running (either with the stock relay or with a bypass wire) then the ECU would be happy. Note: that the fuel pump relay also routes power to dropping resistors & the ECU it'self so if it has some issues you may still not have a car that runs correctly, but it's not because the ECU thinks the fuel pump isn't pumping. +1 on what others said about a pre-filter before you new pump. Also check the stock fuel filter. It is a fine particle filter and over time can get clogged with the fine rust that's coming out of your tank. (I know it looks clean when it sprays all over you, but over time it can still stop up). A partially clogged filter can give symptoms similar to what you're describing. Although usually you start noticing problems when you stomp on it and demand a large fuel flow....not just starting and trying to idle. Len Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 18, 2013 Share Posted December 18, 2013 Note: that the fuel pump relay also routes power to dropping resistors & the ECU it'self so if it has some issues you may still not have a car that runs correctly, but it's not because the ECU thinks the fuel pump isn't pumping. Len You mean the EFI, or main, relay, right? The EFI rely and the fuel pump relay are combined in the same container for 75-77. It helps to distinguish the two when troubleshooting, especially since the FSM separates the two functions. You could disconnect the wire to the fuel pump and install a completely separate relay, but you'd still need the main relay to power the EFI system. Quote Link to comment Share on other sites More sharing options...
superlen Posted December 18, 2013 Share Posted December 18, 2013 NewZed, Yes, I was referring to the EFI main relay inside. I wish Datsun would have named the whole package something with the word "dual relay" in it or similar. And Yes to clarify NZ is right if you just wired directly to the fuel pump and removed the EFI/FP relay you would lose power to a lot of components. Namely: the Aux Air Regulater, the ECU, the dropping resistors, & the cold start valve. One still needs the EFI relay or some external relay to provide power to these components. Len Quote Link to comment Share on other sites More sharing options...
Nightmare_Fairlady Posted December 23, 2013 Author Share Posted December 23, 2013 Ok, so after a few days of messing with it, I had my girlfriends brother come out to look at it. He is a certified mechanic. He plugged a little LED light into my injectors, it didn't light up so I'm not getting any power to them. I found a guy out a ways from where I live, and bought an extra EFI ECU relay from him for 5 bucks, (along with some other miscellaneous parts) and I'm going to put it all on and see if it makes a difference. Wish me luck and happy holidays if I'm not back on before then! Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 23, 2013 Share Posted December 23, 2013 Good luck. Looks like a wild goose chase though (they're faster than they look). You've switched directions entirely from fuel pump doesn't run to injectors don't inject. Did the mechanic turn the engine over and look for flashes or just plug his device in and wait for something to happen? Putting a bunch of new stuff on when you don't know what's bad is a great way to make the puzzle more complicated. At least the relay might be a good investment, for resale. New ones go for over a hundred dollars. Quote Link to comment Share on other sites More sharing options...
Nightmare_Fairlady Posted December 27, 2013 Author Share Posted December 27, 2013 I put all the old parts back on. The only new part was the relay. By the other stuff I meant a cowl, window regulator, stuff like that. The mechanic plugged in a node light to the injectors, had me crank it over and it didn't light up. I still don't have power to the original wires for the fuel pump so its still on my switch. So its getting fuel all the way to the injectors, but doesn't actually inject. The only thing left that I think it would be is the ECU, or the fuel pump relay. I cant find where the fuel pump relay goes, even with the FSM. I do have a couple of wires unplugged but I cant find where they would connect. I don't know. As much as I don't want to, I'm thinking of just taking it to a shop... Quote Link to comment Share on other sites More sharing options...
zack_280 Posted December 27, 2013 Share Posted December 27, 2013 If you are still unsure about the relay, why don't you just jumper across terminals where the fuel pump relay connects? You can do that will a 3" piece of wire and two spade terminals. That will power everything that should have been powered by the fuel pump (assuming you don't have a blown fuse or fusible link upstream). If you still have a problem, you may have a blown injector fuse (or fuses), bad grounding, a bad tach signal to the ECU, or a bad ECU. If you have access to a spare ECU then you should be able to rule that out (or in) pretty quickly as well. Quote Link to comment Share on other sites More sharing options...
Nightmare_Fairlady Posted December 28, 2013 Author Share Posted December 28, 2013 To be honest I cant find the fuel pump relay. Even with the FSM. I got another ecu on craigslist, (crapshoot on whether or not it works) that I'm going to put in in hopes that's the problem. If that doesn't work then I have a factory refurbished ecu at work that I can buy for $200 my cost. I don't have any blown fuses, and the fusible links look alright visually. I want to go through and reground everything as well, I just don't know where to start. The car is about 45min away from where I live and work so it makes it difficult to get to it. Plus it doesn't help that by the time I get off work its already dark. Ah well, suck it up, throw on the old jump suit and grab a flashlight. I'm going to try and get there after work today. Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 28, 2013 Share Posted December 28, 2013 I So its getting fuel all the way to the injectors, but doesn't actually inject. The only thing left that I think it would be is the ECU, Check continuity of the wire from Pin #1 of the ECU harness to the negative post of the coil. That's what triggers the ECU to open the injectors. Quote Link to comment Share on other sites More sharing options...
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