91_4x4runner Posted June 30, 2009 Share Posted June 30, 2009 I haven't been able to get my car started for some time. I purchased it "not running" but was able to get it to *barely* idle for a while. To premise further, when I purchased it, I was told that the fuel pump relay was bad. No biggie I thought, I'll wire it directly. So I did. It would crank over and idle, but I couldn't get it to stay running. I pulled off the fuel rail, thinking I had a fuel problem. Lo and behold, my fuel rail was clogged. A year later, I started working on the engine again. I replaced the fuel rail with an unclogged one and replaced all the injectors with brand new ones. The SOB still won't start. I ran through every test on the EFI bible as follows: Idle Throttle Switch - reads correctly Full Throttle Switch - reads correctly Air Flow Meter Resistance #1 - reads correctly Air Flow Meter Resistance #3 - reads correctly Air Temperature Sensor Resistance - reads correctly Water Temperature Sensor Resistance - reads correctly Control Unit Ground Circuit #1 - reads correctly Control Unit Ground Circuit #2 - reads correctly Control Unit Ground Circuit #3 - reads correctly Control Unit Ground Circuit #4 - reads correctly Ignition Coil Trigger Input Circuit - reads correctly Control Unit Power Input Circuit - reads correctly Injector Circuit #4 - reads correctly Injector Circuit #1 - reads correctly Injector Circuit #5 - reads correctly Injector Circuit #6 - reads correctly Injector Circuit #3 - reads correctly Injector Circuit #2 - reads correctly "Start" Signal Circuit - reads correctly Cold Start System Circuit - reads correctly Air Flow Meter Resistance #2 - Reads 153 ohms, says it should read "small resistance" Air Regulator Circuit - Should read 12V, I got 3V Air Flow Meter Fuel Pump Contacts - It says test pins #10 & #20 but my wire harness to ECU doesn't have a pin 20... Fuel Pump Relay Circuit - Pin 20 to ground - Again, I don't have a pin 20... Air Regulator and Fuel Pump Circuit - 17 mega-ohms initially, but more on this... I followed everything straight by the book. I had only 2 things that pointed to a single system being bad, the Air Regulator. I went through and traced where the Air Regulator connects to. Turns out it connects with the fuel pump circuit at one point. Since I had rewired the pump directly, I wasn't making a ground for the Air Regulator anymore. I created one and the "Air Regulator and Fuel Pump Circuit" tested 60 ohms. Seems Respectable enough for that. Once I turned the key on though, it energized the relay in the engine bay. It started buzzing pretty loud so I quickly flipped it back off. I'm not sure exactly what this relay controls other than the fuel pump, but those things are hard to find. The Air Regulator circuit however, I couldn't get a better reading from. Not sure what the issue is with that other than a bad Air Regulator, though a spare that I hooked up in "mid air" (just plugged it in, not specifically grounded to the engine) read 0V. I guess I need to go and test components specifically... I still can't figure out what the hell is going on... Anyone have ideas? Also, the clutch master cylinder is blown. Would the neutral/reverse switch keep the car from starting? Thanks y'all. Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted June 30, 2009 Share Posted June 30, 2009 Has the AFM been opened? Quote Link to comment Share on other sites More sharing options...
91_4x4runner Posted June 30, 2009 Author Share Posted June 30, 2009 Not sure. I've got a second one that I purchased from a guy on the forum (from a running car). I've tried getting the car started with both of them and had no luck. Quote Link to comment Share on other sites More sharing options...
JoeinCA Posted June 30, 2009 Share Posted June 30, 2009 Ok... Obvious questions. Did you check the fuel filter and check for adequate fuel pressure at the rail? Have you tried purchasing(or swapping) a relay and wiring the fuel pump back up as originally intended? Are you getting spark? Have you checked for voltage leaks?(I just run my hand along the wires) Are you sure you arent playing with the wrong circuits? Have you moved the flap inside of the AFM across its entire range and checked for ohm holes? There are still some pretty easy things that could be happening. I had a no start because the afm had a pebble stuck in it. (how the pebbles got there... I'll never know, ended up with one holding the egr open too). Good luck with it, Don't let electrons beat you. Joe Quote Link to comment Share on other sites More sharing options...
91_4x4runner Posted June 30, 2009 Author Share Posted June 30, 2009 Yes, I guarantee I'm getting good fuel pressure. Yes, I'm sure I have spark. I guess I should mention that the car will start/run off starter fluid. It's got about a 1/2 tank of gas as well... I have not tested the AFM through its entire range, but it tested fine by the EFI bible. I'll do that next. I'm sure that I'm not messing with the wrong circuits, but my car seems to be a hackjob in wiring. All signs point to go but my injectors just aren't firing. Quote Link to comment Share on other sites More sharing options...
JoeinCA Posted June 30, 2009 Share Posted June 30, 2009 AH. No fire in the injectors. Did you verify with a light? I'd check the ground circuit for the injector harness, and make sure that the flap inside the afm moves freely. 1/2 tank of gas... 2 year old gas? Joe Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted June 30, 2009 Share Posted June 30, 2009 What was the Fuel Pressure at? Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted June 30, 2009 Share Posted June 30, 2009 Pull the fuel filter and see if its rusty. I went through several filters before I bought a different non-rusty tank. Quote Link to comment Share on other sites More sharing options...
91_4x4runner Posted June 30, 2009 Author Share Posted June 30, 2009 AH. No fire in the injectors. Did you verify with a light? I'd check the ground circuit for the injector harness, and make sure that the flap inside the afm moves freely. 1/2 tank of gas... 2 year old gas? Joe I haven't verified with a light. I'll do that. The flap inside the AFM does move freely. The gas is less than a month old. I don't have an actual measurement, but I've made several f-ups with the fuel. IE: Forgetting to reconnect the line and watching gas shoot out & disconnecting the line while still under pressure. I have given each injector 12V and they all click as well. I'm thinking it must be a relay or the drop resistors. Quote Link to comment Share on other sites More sharing options...
91_4x4runner Posted July 1, 2009 Author Share Posted July 1, 2009 Checking in again. The relay that was buzzing seemed to be grounding on its casing. I just took it apart, checked that it was functional and put it back together. I have it re-energized and it seems to be working perfectly now. Also, I tested and found that I'm getting 0V to the injectors whether cranking or not. The one thing that I forgot to check was between the positive lead and a different ground. My troubleshooting leads me to believe that either the EFI relay or the dropping resistors are going bad as these are the only things between the computer and the injectors. Of course though, my computer could be bad too. Quote Link to comment Share on other sites More sharing options...
JoeinCA Posted July 1, 2009 Share Posted July 1, 2009 Let me look through my parts to see if i cant find an efi relay or dropping resistors... IF Its nice to be able to test directly to the battery ground, a good way to help find bad grounds and gives you consistency that allows you to find more inconspicous electrical problems. What relay was buzzing? Ok, I found an extra efi relay. And the FSM... Pull the EFI relay out, (from above the ecu). Put 7-12 volts to terminals 86c and negative terminal 85. You need to have continuity between 88z and terminals 88 a and b. Terminal 88b provides voltage to the dropping resistors. If that checks out, then pull the dropping resistors and check for about 6 ohms. If that all checks out, bash your head in with the meter. Joe Quote Link to comment Share on other sites More sharing options...
91_4x4runner Posted July 1, 2009 Author Share Posted July 1, 2009 The fuel pump relay in the engine compartment was buzzing before. It isn't since I took it apart and verified that it functioned correctly. However, I can't find any sort of EFI relay. There doesn't seem to be any relay or spare plugs above my ECU. I'll take a picture to show you, but all there seems to be is the ECU and chassis behind it. I feel like a complete moron. In other news, it seems that my cold start injector is firing (though according to the wiring diagram, its separate from that relay). The car wants to crank over for the first few turns of the starter but goes back to just cranking (fuel-less sounding) after that. I hate my fuel injection. Quote Link to comment Share on other sites More sharing options...
91_4x4runner Posted July 1, 2009 Author Share Posted July 1, 2009 I found the area where its supposed to be installed in the car. I see the mounts for it, but it simply isn't there. Again, I don't see any unused plugs either. Did the location change on the 78 model? The closest thing I could find to a "double relay" unit (2 relays in one box) is in the engine bay in the relay box by the battery. However, it only has 5 plugs. Quote Link to comment Share on other sites More sharing options...
JoeinCA Posted July 1, 2009 Share Posted July 1, 2009 Wierd. The relay is kind of a pain to remove. I know it was there on my 75 280, and it was there on my 77 280. It is behind the hood release handle mount. held in with 2 phillips bolts. Below is what it looks like.. I have to go digging around today anyway, if I find a computer or the resistors, and you need one, both, or all three components, they will be very cheap. Strange that you dont see the wires there. Joe Quote Link to comment Share on other sites More sharing options...
91_4x4runner Posted July 3, 2009 Author Share Posted July 3, 2009 As it turns out, the 77 EFI relay is different from the 78 EFI relay. According to my manual (Haynes or Chilton, can't remember which), the 78 model has a smaller EFI relay with fewer pins and uses other relays (Fuel pump relays 1 & 2) to control other things. Problem is, I'm missing my Fuel Pump 2 Relay and still can't find my EFI relay according to the colors and wire diagrams. I've disassembled, tested and reassembled just about every relay I can get my hands on under the dash. None of them make a difference. I'm going to pick-n-pull tomorrow to find a new drop resistor. It might not work (as much of my pick-n-pulls stuff is crap) but who knows. I feel like pushing my car off a cliff.... Quote Link to comment Share on other sites More sharing options...
91_4x4runner Posted July 4, 2009 Author Share Posted July 4, 2009 Alright. Found the EFI relay on the 78. Its on the relay bracket under the hood. I was reading the wiring diagram to be Blue/Green instead of Blue(switch wires)Green. Obviously, I'm an idiot. After that was over, I retested my relay. Turns out, it doesn't make a 100% connection and the ground is flakey on it. I rigged it up and tested at the ECU. I'm getting a good 12V at all fuel injectors and ECU power. However, when I test at the injector connectors, I get 0V with the key in any position. Shouldn't I be getting some voltage in the ON position or while its cranking? I guess this limits everything down to my ECU or the dropping resistors.. Anyone have any ideas or information they could share? I *assume* my ECU is alright since my cold start injector will fire when the engine just starts cranking. Quote Link to comment Share on other sites More sharing options...
91_4x4runner Posted July 6, 2009 Author Share Posted July 6, 2009 What kind of signal should I see at the injectors? Should they have 12V? Should they read a certain resistance? I replaced my drop resistors and it didn't help. I'm hoping my computer isn't broken, but its starting to look like it is... Quote Link to comment Share on other sites More sharing options...
91_4x4runner Posted July 9, 2009 Author Share Posted July 9, 2009 I don't mean to bump/triple post, but I need to know what kind of signal I should see at the injectors... Some sources say 12V; I don't have that. I see no voltage change while the ignition is on or the engine is cranking. It stays at 0V. Quote Link to comment Share on other sites More sharing options...
m4xwellmurd3r Posted July 9, 2009 Share Posted July 9, 2009 if that's the case, then you've got something going on in the circuit for them. I don't know exactly which it could be, but I do know, that if you have a lot of corrosion on the fuseable links, that sort of symptom could occur. I freaked out when my Z wouldn't start, and that was the problem the entire time. Quote Link to comment Share on other sites More sharing options...
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