liveforeverZ Posted May 2, 2009 Share Posted May 2, 2009 Hey, Z was running awesome until I changed to hotter plugs. Then it stopped running. Thought maybe it was the plugs (checked - it wasnt), then timing (checked, not that either). Its getting fuel and spark, but wont start (turn over great though) Checked compression 152,152,148,150,148,150 (very cool for a never restored engine) I checked the pressure on the fuel line (38 psi) so that passed. I got it to start by putting my compressor nozzle right into the fuel rail and blowing 75psi into the line while turning the car over. It started right up. So for some reason, my car wont start unless it gets 75 psi to the injectors. I'm thinking maybe pressure regulator - any ideas? Quote Link to comment Share on other sites More sharing options...
cali260Z Posted May 2, 2009 Share Posted May 2, 2009 crossed plugs? did you check the routing to the plugs and make sure the firing order is right? not that ive ever done that before or anything........................... Quote Link to comment Share on other sites More sharing options...
jbk240z Posted May 2, 2009 Share Posted May 2, 2009 I have a stock '78 Z fuel regulator if you would like to try it. $3.00 + shipping. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 2, 2009 Share Posted May 2, 2009 Check your battery voltage during cranking. If it drops too low while cranking, the injection won't fire the injectors. I think it's a 9 volt threshold during cranking if I remember right. Also make sure you didn't knock into the fusible links while you were wrenching on the plugs. Check those, and then try starting with a battery charger connected. Quote Link to comment Share on other sites More sharing options...
jasper Posted May 2, 2009 Share Posted May 2, 2009 Check your coolant temp sensor. If it thinks the engine is hot, you won't get cold start enrichment. Ever try to start a carbuerated car with a broken choke??? Raising the fuel pressure just adds more fuel...(artificial cold start enrichment) Quote Link to comment Share on other sites More sharing options...
liveforeverZ Posted May 2, 2009 Author Share Posted May 2, 2009 Thanks guys. I've actully got another pressure regulator I'm gonna drop in. I've also got another coolant sensor I could put in as well. I checked the amperage on the batt, as well as firing order and all that. Battery was 8.8 cranking, so I think thats close enough to 9 to start it. Firing order was on. I'll put those two pieces in this week and see if anything budges. I just thought it was strange that when I doubled the fuel pressure, the car ran fine. Thats why I thought it may be a broken regulator or whatnot - but jasper, I will def. put the temp sensor in and see if the cold start was the problem. thanks Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 2, 2009 Share Posted May 2, 2009 Not amperage, voltage. If you were only reading 8.8 volts, the injectors will NOT fire. Quote Link to comment Share on other sites More sharing options...
liveforeverZ Posted May 3, 2009 Author Share Posted May 3, 2009 i'll drop a battery with more juice in it today and see what happens Quote Link to comment Share on other sites More sharing options...
liveforeverZ Posted May 3, 2009 Author Share Posted May 3, 2009 Wasn't the battery or the temp sensor. Is there a way to see if the injectors are firing? Like I said, the only way it starts is if I put the fuel in the cylinders, or if I blow into the fuel rail w/ a compressor while starting the car. It only runs then for seconds. This car was running perfect a few days ago. Also, as an aside, my fuel in my tank has turned red, and is burning brown. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 3, 2009 Share Posted May 3, 2009 Strange. How would fuel discolor? Rust? Ruptured fuel filter? That could have spewed muck into the injector screens and clogged them all up. Quote Link to comment Share on other sites More sharing options...
liveforeverZ Posted May 4, 2009 Author Share Posted May 4, 2009 Any good ideas on unclogging injectors? Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 4, 2009 Share Posted May 4, 2009 There is a thread about cleaning injectors. Take them out, energize them with around 3-6 volts DC and back flush them with a solvent or gasoline. You can also send them out. Make sure you flush all the fuel lines and tank too. Quote Link to comment Share on other sites More sharing options...
liveforeverZ Posted May 5, 2009 Author Share Posted May 5, 2009 Hey, I multimetered the injector plugs while turning it over. It only showed .1 volt pulsations. I am sure that isnt enough to start them right. And the negative pulse was -.1v pulsations. Quote Link to comment Share on other sites More sharing options...
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