9rider Posted May 3, 2013 Share Posted May 3, 2013 Story : I bought my first Z car about a month ago. Owner claim the car had not started since 2000. I drained all the gas tank. No rust came out, lucky. However, most of the fuel hose melted and messed up the pump. I changed the pump to MSD 2225, changed all the fuel hose around the pump, and fuel hose around the filter. Blow air to return line to make sure no stuck. blow air to feeding line make sure no stuck. Car started and ran but hesitate around 2000 RPM. I checked MAF, TPS, cleaned both. All good, Suspect either fuel damper or fuel filter clog up ( I didn't change the fuel filter yet) And now the problem: I disconnect all the spark wire, disconnect distributor wire on the distributor side and still plug at the ignition side and left it hang around the engine compartment. Ran power thru the cold start valve to release fuel pressure. After that, I change the fuel filter, installed inline fuel pressure gauge after the fuel filter, Crank the engine to make sure no leak, engine didn't start , of course all spark plug wire unplug. I totally forgot that I unplugged all the spark plug wires and crank it couple more time. Fuel pressure reading 32 PSI indicated fuel pump worked. I plugged all the spark wires back as of diagram 1 5 3 6 2 4 . And I couldn't get injector to tap again. I checked both relay on driver side, cold start valve. Test fusable link, all good. Test the ignition coil , get reading of 12V. My question is : did I flood the injectors when I cranked that many time? and cause it to damaged? The ignition coil wire might have touch the frame and short out the fuse or relay somewhere? , if it posible. I didn't test the ECU or the drop resistor yet. I searched but could't find similar topic relate to my dumb problem. Most of topic related to AFM and pump relay. Please help as I live in apartment and park my car on street, I have to push my car around 1 every 2 days to avoid ticket from city. Quote Link to comment Share on other sites More sharing options...
Domzs Posted May 4, 2013 Share Posted May 4, 2013 Need info on your car . How did you check for injector pulse ? Did you check to see if you have bat. voltage , key on and start pos. , at one of the two wires at injector connector ? Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted May 5, 2013 Share Posted May 5, 2013 First of all I would spray carb cleaner into the intake manifold, that will be sure whether it is a fuel problem. If it starts check if there is pulsing at the injector by plugging a test light into the injector plug by probing one side and grounding the other. I would use a paper clip to interface it into the plug and use jumper wires. crank for pulse. If there is a pulse, check injector resistance on each injector. If you find one with improper resistance, unplug the injector then attempt to start it. If no pulse, the wiring should be checked going to the ECU and to the Ignition module. Quote Link to comment Share on other sites More sharing options...
9rider Posted May 5, 2013 Author Share Posted May 5, 2013 I am getting 12v at both plugs of injector. Same as this topic here http://forums.hybridz.org/topic/112559-no-ground-to-injector-ecu-ok/?hl=toinjector Do you think dropping resistor have anything to do with this? I will try to spray carb into the intake now , but if it run for couple seconds then it proves have ignition , don't see how to know there is fuel problem. Quote Link to comment Share on other sites More sharing options...
9rider Posted May 5, 2013 Author Share Posted May 5, 2013 Oh, I did check more into the pass side relay, don't know if that relay for fuel pump or injector but it worked fine. Sorry didn't mention year of my car. It is 1976 California model , base 2 seats. Quote Link to comment Share on other sites More sharing options...
Domzs Posted May 5, 2013 Share Posted May 5, 2013 Use a noid light or low amp. test light to check for inj. pulse . Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted May 5, 2013 Share Posted May 5, 2013 That was how i diagnose a no start, I missed the running for 2 second part, haha. There must be something that keeps you from getting fuel. Ill have to think about that. I was thinking of your MAF not opening to trigger the fuel pump, because iginition signal will do it to start the engine. You might want to have the fuel pressure gauge on while you attempt to start the engine. This situation seems familiar so i will come back with more information. Quote Link to comment Share on other sites More sharing options...
9rider Posted May 5, 2013 Author Share Posted May 5, 2013 (edited) Yes, I installed fuel pressure gauge after the filter ( permanent ) . Fuel pressure rose up when crank and when I flapped the MAF, i could hear the hissing noise from the fuel regulator - doing its job . Fuel getting in the cold start valve too. I measured voltage on all injector plugs. Both plugs getting ( + battery voltage)/ - ground to engine block , I say this because the starter caused it go up and down + - couples volt when I crank . This stopped when I removed yellow/black wire to the starter. Both plugs of injectors have almost identical voltage when key in on position and didn't change value when I cranked. I checked ignition plugs with the spark test tester and light (ON) on all sparks. Also got shock too ( ). I removed the ECU , unplugged . Voltage on injectors showed battery voltage on only 1 plug when key on position and didn't change when crank. I didn't spray Carb cleaner into injector because last time I sprayed , I almost burned both of my eyebrows ( coz I spray likely 1/4 of can into the air intake and caused it to back fire back to the front of the intake) -- too scare until now. I found there is member have same problem as me when he switched the harness. But his topic still unanswered. All of this point me to 2 areas: the ECU and or the dropping resistor. I took the ECU apart, forget me for being dumb, looked into those resistor and hoped seeing melted or fried one. ( given this is old car and giving its old school way) , didn't see any burn or melted and everything seemed intact. Hope the guy have same situation with me found the solution and will chime in. In the mean time , I am really don't know what to do and i am really appreciate all helping that I got from you guy. Edited May 5, 2013 by 9rider Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted May 5, 2013 Share Posted May 5, 2013 Okay I did not see the information about the engine harness swap. I have a '76 which I swapped a '77 harness to. There was one difference in the harness which I had do modify my harness to make it start. There is a wire which sends a pulse to the ECU to pulse the injectors. Look at the wiring diagrams for the differences. I will post a picture when I get the chance but I am positive that is your issue because I had the same exact problem. I dont remember to precisely what size of connector it was but one harness had a 4 pin connector with a stray connector, and the other harness had a 6 pin which included the stray wire. I think the '76 had the 6 pin and the '77 had the stray one. Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted May 5, 2013 Share Posted May 5, 2013 It should be under the drivers side dash btw. Quote Link to comment Share on other sites More sharing options...
9rider Posted May 5, 2013 Author Share Posted May 5, 2013 I believe my car is stock wire-harness and I didn't change or mod anywire. But there is some wires don't look stock. I was mention about the other topic when the guy ( atl-adam) swap his wire from 76 into his 77. Thanks for all your help. Quote Link to comment Share on other sites More sharing options...
Domzs Posted May 5, 2013 Share Posted May 5, 2013 Just to make sure if you have inj. pulse or not . Unplug all your inj. connectors then plug a noid light or a LOW AMP. test light to a inj. connector . Crank the motor to see if the light flashes . With the connector unplugged , one wire should have bat. voltage ( key in on and start pos. ) and the other one should ground ( neg. ) when commands by the ECM . If you back probed the connector while it still connected to the inj. , with key in on pos. it will show bat. voltage on both wires until you crank the motor then one will go to neg. . Works like the ign. coil . Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted May 6, 2013 Share Posted May 6, 2013 Yeah the Pulse from the coil will go to the ECU Pin #1. That is what this Bosch system uses as CPS. Quote Link to comment Share on other sites More sharing options...
9rider Posted May 6, 2013 Author Share Posted May 6, 2013 I just dl injector TB handbook and will test all 35 pin. Let yall know later. Quote Link to comment Share on other sites More sharing options...
9rider Posted May 7, 2013 Author Share Posted May 7, 2013 (edited) I tested all the ECU pins. Idle throttle switch Full throttle switch AFM resistance 1, 2, 3 Air temp sensor resistance AFM fuel pump contacts Water temp sensor resistance Fuel pump relay circuit Air regulator and fuel pump circuit Control unit ground circuit 1, 2 , 3 , 4 Ignition Coil trigger input circuit Control Unit Power input circuit Injector circuit 4,1,5,6,3,2 Start signal circuit Air Regulator Circuit Cold Start System circuit All of them showed within the ranges or values indicate in TB manual. So this come to final conclusion is my ECU broken? Is there any other way to test or check without replace the ECU. I am afraid that I will busted the new one if I don't find out what is wrong or I end up getting the new ECU and problem still exist. I ran check on the injectors with both plug off the injector show battery voltage at key " on" position, didn't change when start. But when I used Amp meter test the injector plugs ( unplugged) with pos lead to 1 of the plug and neg lead to air intake body , I heard injector tap and fuel pressure drop right away ( key " ON" ). This happened to only one plug of the injector pigtail. PS: my car ran fine ( a little hesitate when rev up) until I change the fuel filter and add the fuel pressure gauge. I disconnected the fuel hose right in middle of the rail and fuel come out -> fuel get through pressure gauge and the new filter. Edited May 7, 2013 by 9rider Quote Link to comment Share on other sites More sharing options...
Domzs Posted May 7, 2013 Share Posted May 7, 2013 So you have fuel press. and spark . Have you tested for inj. pulse ? Check for corrosion on injectors and connectors , common problem . Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 7, 2013 Share Posted May 7, 2013 PS: my car ran fine ( a little hesitate when rev up) until I change the fuel filter and add the fuel pressure gauge. I disconnected the fuel hose right in middle of the rail and fuel come out -> fuel get through pressure gauge and the new filter. You might have switched hoses. Inlet for outlet. Check that the hose from the filter is attached directly to the rail and not to the regulator. Earlier you said that fuel pressure rose but you didn't say what it rose to. What was the pressure on the gauge? Quote Link to comment Share on other sites More sharing options...
9rider Posted May 7, 2013 Author Share Posted May 7, 2013 (edited) @4.6Stang: Which wire you mention about? I took couple picture under dash driverside. @Domzs: I have fuel pressure raise up to 33PSI when crank and ~36 PSI when AIM Flap pressed. @NewZed: I ran fuel line correctly as you see above. I switch battery from another car, 600 CCA , cranked it up and nothing happened. Edited May 7, 2013 by 9rider Quote Link to comment Share on other sites More sharing options...
4.6StangRage Posted May 7, 2013 Share Posted May 7, 2013 i cant tell from the pic for it is too small. ill take a pic of mine today. Quote Link to comment Share on other sites More sharing options...
Domzs Posted May 7, 2013 Share Posted May 7, 2013 Pics are too small . And you haven't answered my question about the injector pulse . Quote Link to comment Share on other sites More sharing options...
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