mom'sZ Posted July 5, 2005 Share Posted July 5, 2005 Hello everyone I have a 77 280z, fuel injected, pretty much totally stock. It won't start, cranks over forever, then when it does start, it sounds like it is running on three cylinders. Then... it will clear up and run fine for a minute, idle and rev, then almost stall again. The car is pretty much undriveable. About two weeks ago it stalled idling at a light a few times. I turned up the idle (it was idling at 600 rpm) and it was fine, stopped stalling. Then one day last week it started real hard and then acted like it was running on three cylinders, finally cleared up and ran fine. Then this morning, it wouldn't start, when it did it ran like on three cyls then stalled and would not start. Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted July 5, 2005 Share Posted July 5, 2005 I would start by checking the fuel filter to see if it was plugged up and then the fuel pump. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted July 5, 2005 Author Share Posted July 5, 2005 my first thought as well, I unplugged the hose from the fuel rail and pointed it into a soda bottle and when I cranked it very breifly fuel came out, quite a bit in fact, although it (the fuel pump) could still be bad. But anyhow, this was upstream of the filter so it's not totally clogged. Quote Link to comment Share on other sites More sharing options...
Forrest Posted July 5, 2005 Share Posted July 5, 2005 Check to see if all your injectors are firing (listen to them with a screwdriver) - and check the connectors to make sure they're making good contact with the injectors. Make sure you are getting spark on all 6 cylinders. Check your fuel pressure between the rail and the filter. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted July 5, 2005 Author Share Posted July 5, 2005 what should the fuel pressure be? Quote Link to comment Share on other sites More sharing options...
Phantom Posted July 5, 2005 Share Posted July 5, 2005 You'll get some opinions on fuel pressure but the gage I installed on mine generally indicated around 35 psi at the inlet to the injection rail. This really does sound like a fuel restriction problem to me. You could have crap in your tank that is partially plugging the exit strainer. I'd get a 5-gallon pail and run the system long enough for a good delivery test. If it drops off after a while you've got debris in your tank. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted July 5, 2005 Author Share Posted July 5, 2005 OK fuel pressure 35 psi at idle, jumps up to 40 when you blip the throttle Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted July 6, 2005 Author Share Posted July 6, 2005 is the fuel pressure gauge supposed to jump around? It's steady at an idle, but when you open the throttle it dips then quickly jumps up higher then it was at an idle. I read last night that the fuel regulator is supposed to keep it steady, is this true? Quote Link to comment Share on other sites More sharing options...
Phantom Posted July 6, 2005 Share Posted July 6, 2005 What you saw is normal. It takes the regulator a small amount of time to respond to the throttle movement. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted July 6, 2005 Author Share Posted July 6, 2005 Hi everyone phantom: thanks for the info, yes I see that now (as you'll see below) This a daily driver and usually very reliable. I found some non-stock fuel line that seemed to be causing the problem last night and replaced it. Now the car starts and runs perfect. But all the sudden it stalls and won't easily restart. So I go back home and rig the fuel pressure gauge duct taped to the cowl so you can see it while driving. And I drive around. It reads 30 psi at idle, rises slowly as you open the throttle, and hits 40 psi when you floor it. Seems the fuel pressure regulator and fuel pump are working well. Then sometimes when you are going down the road, or pulling away from a light it just dies. As it dies, I'm looking at the gauge and it reads normal, plenty of pressure. So... I'm thinking it might be something else. Anybody still reading this thread please feel free to chime in. I don't want to have to start throwing parts at the car to try to diagnose it Quote Link to comment Share on other sites More sharing options...
Phantom Posted July 6, 2005 Share Posted July 6, 2005 Do you have a factory service manual? You can get one on CD from Courtesy Nissan in Irving, Texas. Unfortunaetly there are several different problems that could give you the symptoms your're experiencing and the FSM would really help you there. I haven't had the L28 in my car for long enough now that I've forgotten most of the little things in that area. If you're fuel pressure is staying up then it comes down to electrical or air. Pull the plugs and look at them and see if they are sooty or wet from fuel. Quote Link to comment Share on other sites More sharing options...
Forrest Posted July 6, 2005 Share Posted July 6, 2005 Your fuel pressure sounds fine. Check your distributor shaft for play and make sure it is bolted down tightly. Make sure all your plug wires are secure. Never hurts to change your cap and rotor if it's been a while. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted July 6, 2005 Author Share Posted July 6, 2005 Thanks for the suggestions guys, I am checking some of the things you mentioned as we speak. Phantom: yes I do have a Factory service manual, hardcopy, a little dog eared, but I'm pouring through it. Looking for the test procedures for some of the suspect parts. Forrest: plug wires, cap & rotor are new. I too am convinced fuel delivery isn't an issue. I have several things I suspect but any help would be great if you are familiar with the stock ignition & FI on a 77. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted July 9, 2005 Author Share Posted July 9, 2005 Update: car still stalls Have be going over stuff on the car, testing as per the FSM. Found the Air regulator wire very loose. Connection to it (similar to a fuel injector's) was broken where it plugs to the air regulator. In the manual it runs to the fuel pump. Does anybody know if this connection to the air regulator being loose would cause my stalling problem? I live in a warm climate, could I toss this thing and plug the connection in the TB boot? If I did, would I need to bridge the two wires that go to it or just leave it unplugged? Quote Link to comment Share on other sites More sharing options...
Phantom Posted July 11, 2005 Share Posted July 11, 2005 Air regulator not functioning will really screw you up. It works in conjunction with the cold start valve in controlling your air-fuel ratio during start and then changes position for the "run" mode. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted September 4, 2005 Author Share Posted September 4, 2005 I guess I'll revive my own old thread because I'm still having trouble getting the car running. I'd like to rediscribe the problem as I've had time to really diagnois it. Originally, the problem manifested itself as a stalling issue. When it would do so it was usually at a light. To review this is a almost completely stock F.I. 77 280Z. As I tried to diagnois the problem I noticed it would also do it going down the road. You'd be driving along and it would die like somebody unplugged something, then come back to life. This was a daily driver, ran ok and I had to do very little to keep it running. So, here's what I've done. (see above) wires, plugs cap rotor. All hoses for fuel and vacumn on engine. Install gauge to see fuel pressure. Checking everything on the whole engine I came across the fact that the connections to the fuel injectors were corroded. At that point you couldn't even drive it, and it would barely start and ran on three cylinders when it would. Some contact cleaner and fiddling got them temporarily going and it seemed to run better. So... I got six brand new injector and new wire ends, redid the harness and install injectors. Fixed connections for air regulator and cold start do-hicky while at it. OK so... I really felt the injector connections were not the main problem. But I felt further diagnoisis could not continue until they were replaced. And I figured it would take care of the running on three cylinders thing. And believe me, one night in frustration I started yanking plug wires off and it truely was running on three. When I would yank them off you could hear the spark going teh teh teh, so you know that was working. Sorry long post, so, I replace injectors. Now I try to start it. Runs like on three again. Won't idle, won't even start if I don't get in and hold the throttle open a tad. Then when it starts, it runs like it's running on three cylinders, You try to rev it, it is pouring out blue white smoke and won't rev. Then suddenly it goes, runs on all six and revs like an Indy car. Then more smoke and won't rev again. won't idle, stalls out. HELP, HELP, please anybody Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted September 6, 2005 Author Share Posted September 6, 2005 Well ... in case anybody reads this thread... I GOT IT!!!! It was the water temp sensor for the fuel injection. Once the new injectors were in and it was running full rich, hence the blue smoke. So the temp sensor was a logical next guess. 17 bucks! Car idles, pulls strong, runs good. Quote Link to comment Share on other sites More sharing options...
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