Z_Rac3r Posted October 21, 2009 Report Share Posted October 21, 2009 Can anyone help me explain the newest mood swing my car has taken on... So after the whole gas in the eye escapade, skibby took me to work the next morning and he went to start up the Z when he got back to my house and it fired right up. Since then its died 3 other places, It runs perfectly fine when It does run. after you start it, drive around and park it, it wont start again. until it sits for at least an hour. Until yesterday morning when It wouldnt start at all. I changed the fpr and got a new filter in there and then it was trying to turn over and every once in a while would run on a few cycles but couldnt sustain an idle. This morning I finally got it running where it will start up consistantly but its got a little knock and I can't tell if its burning oil or a little bit of coolant. its not huge... yet... as in if the head gasket just took a crap, it literally JUST took one and hasn't been driven on. I'm about to check valve clearances because I've always had one that rattles loose every 6 months and its been about that long... but I'm afraid its going to go back to not starting... Ive gone through all the fuel injection and it makes no sense why it would be starving it fuel... the ignition is fine, the fuel... should be fine, and air is fine... the basics are all there. The weirdest part is before when it was an intermitent problem, when it ran it ran PERFECT, never died or had trouble while running. Anyone up for wrenching at my place? :( or if you have any suggestions I'm all ears. call me as I'll be outside wrenching. 805 895 8462 I live in Beaverton/Aloha. if some of the smog crap is acting up... would it have an affect like this on it? since I'm not in CA anymore I'm sure all that stuff can go ;) Quote Link to comment
datzenmike Posted October 21, 2009 Report Share Posted October 21, 2009 Maybe put some methyl hydrate in the tank to absorb any moisture? If you suspect a h/g run a compression test looking for a low cylinder or two adjacent low cylinders. Check the plastic piping from the throttle to the air meter. It's old and may have small cracks letting in air that throws the setting off. Quote Link to comment
Duke Posted October 21, 2009 Report Share Posted October 21, 2009 Are you SURE the igintion is good? I recently had a problem with my car not wanting to start after parking it from a drive. Once it cooled down it would start fine. I had thought that the igintion was good, but the problem continued to get worse and the car started missing fairly badly at higher rpm. I was eventually able to track it down to the coil. Once I replaced it, I have had no problems since then. Quote Link to comment
fastdadd Posted October 21, 2009 Report Share Posted October 21, 2009 i had the sock filter in the fuel tank go bad and had a similar problem Quote Link to comment
yello620 Posted October 21, 2009 Report Share Posted October 21, 2009 Do you have a fuel pressure guage to monitor and verify proper fuel pressure? Quote Link to comment
DanielC Posted October 21, 2009 Report Share Posted October 21, 2009 I do not know exactly how the fuel injection on your car works, but I have a fairly good idea on the how it works on my boat. I also do not know if they were using O2 (oxygen) sensors when your car was made. I am assuming that your car does not have one, due to its age, but there is a good possibility I am wrong about that. The critical piece of information you must have when you have fuel injection driveability issues is the fuel pressure. This is even more critical without the O2 sensor, because the engine does not have any feedback on the air/fuel ratio without it. Quote Link to comment
Skib Posted October 21, 2009 Report Share Posted October 21, 2009 This is even more critical without the O2 sensor, because the engine does not have any feedback on the air/fuel ratio without it. Iv got an extra O2 sensor if you want it, just let me know Quote Link to comment
Z_Rac3r Posted October 21, 2009 Author Report Share Posted October 21, 2009 Not absolutely positive that the ignition is good... but wouldnt it act up when the car got running? when it runs, the fuel mixture, timing, ignition, is perfect... no problems. The filter in the tank could explain it seeing how the filter was really gross... I could be picking up crap from the tank and it clogging the hard lines... but again, wouldnt it clog and have problems when its running? Id think so. Same thing for moisture in the tank. The mixture would be the same while the car is running, so It be running pretty crappy then too. I was thinking about the fuel pressure.... and I can't find my new gauge, its a manual guage and the stock one is electric. Skibby said he might have an extra oil pressure gauge I could rig up to check it. But would oil pressure really effect it starting? I wouldn't think so, oil is just to release heat, clean, and lube, I couldnt see the car not starting because of lack of oil pressure. It makes no sense why it runs perfectly fine when it does start. Unless its the coil... I need to go grab my spark plug socket from my buddy to make sure I'm getting spark all the time. But alas.... I just checked the valve clearances... nothing was off by more then 1-2mm :/ but I was a qt low with oil... its starting up now on every try, after I went through the valves and added more oil the chatter/slight rod knock sound is really minimal, I think I was just paranoid and overhearing the valve chatter since there wasn't enough oil in there. Not much to dampen the sound. I'm going on a test drive... wish me luck! :( Oh and after I added oil... the exhaust looks clean, no smoke and smells normal. Before it smelled normal, the little smoke just had me worried. Quote Link to comment
Z_Rac3r Posted October 21, 2009 Author Report Share Posted October 21, 2009 I didnt think 280s had an 02 sensor... I'm about %60 sure of that... but theres a 40% chance I'm wrong... My exhaust has all been redone though, by the previous owner. Last time I did a head gasket, I took all the exhaust off and I know there was not an 02 sensor.. because at the time I thought it was weird lol... so if its supposed to have one, I will add one... but my car has been running fine without one for at least 3 years. Could it be anywhere other then the headers back to the tail pipe? I'll look again incase though, I could be wrong. Quote Link to comment
datsunaholic Posted October 21, 2009 Report Share Posted October 21, 2009 There's no O2 sensor on a '78. Quote Link to comment
Skib Posted October 21, 2009 Report Share Posted October 21, 2009 I didnt think 280s had an 02 sensor... I'm about %60 sure of that... but theres a 40% chance I'm wrong... ya I wasnt sure either :P the ZX L28 dose but I couldn't remember if the Z L28 did Quote Link to comment
Z_Rac3r Posted October 21, 2009 Author Report Share Posted October 21, 2009 Soooooo I went on a test drive, she ran amazing, and I stoped at a stop sign and she died.... soo I skated home, :( wif no Z. It didnt sputter, it just went from running, to.. dead. I think you are right about the coil Duke... Its the only thing that makes sense at the moment. If it was the fuel pump (I've already laid under the car while you try to start it, and the pump turns on.) but I mean if the pump is going bad or possibly clogged, wouldn't it at least sputter before it died, or have problems running normally too? Quote Link to comment
Duke Posted October 21, 2009 Report Share Posted October 21, 2009 I have heard this from a few people...90% of fuel problems are ignition related. Quote Link to comment
Skib Posted October 21, 2009 Report Share Posted October 21, 2009 I have heard this from a few people...90% of fuel problems are ignition related. ya right now its looking like your right about the coil Duke, Im digging threw my boxes for a spare atm Quote Link to comment
nis720 Posted October 21, 2009 Report Share Posted October 21, 2009 I vote electrical issue. I had a friend have a similar problem, as soon as i got there I found the plug near the battery has barely on. :D Quote Link to comment
Z_Rac3r Posted October 21, 2009 Author Report Share Posted October 21, 2009 Yup, I agree. The cap and rotor are fine though, the starter turns over and tries to run, its new. Everything else electrical works, so Its not as simple as a battery connection. I wish I could pull a plug right now while its dead to verfiy its not getting spark. As I think about every issue its having, the coil going out can explain them all down to a tee. Maybe the insulation in the coils are starting to get burned up. That would make sense after it sits for a while, everything cools down and the metal contracts, it will function again until it heats up and the wires rub. Either that or a wire in the coil is loose sometimes and it cant produce the magnetic feild. That would also explain why when its trying to start it 2-3 cylinders will fire everyonce in a while because maybe the coil is getting weaker and weaker and can only build up a second of current strong enough to make it arch. Thanks for the help guys. I'll let you know if it works! Quote Link to comment
benzo Posted October 21, 2009 Report Share Posted October 21, 2009 just throwing this out there as I have seen other cars do this. does the Z use a fuel injection main relay to control ecu or fuel pump? if so maybe that is bad or going out. I have seen this on other cars that run well then when you shut off they don't start until they cool down. the relay may be getting hot Quote Link to comment
DISLEXICDIME Posted October 21, 2009 Report Share Posted October 21, 2009 check voltage at the relay and at the pump i wonder if your match box is coroded Quote Link to comment
Six_Shooter Posted October 21, 2009 Report Share Posted October 21, 2009 Stock L28 EFI? Disconnect the plug at the ECM, clean the contacts, that seems to work for many people, when they are experiancing problems with these early EFI systems. Quote Link to comment
hang_510 Posted October 21, 2009 Report Share Posted October 21, 2009 i second (or third) the coil and/or connectors I have heard this from a few people...90% of fuel problems are ignition related. EYE! :cursing: if you think its electrical, its fuel... Quote Link to comment
sssr20det510 Posted October 22, 2009 Report Share Posted October 22, 2009 do you have an electrical dizzy? its deff an electrical problem usually a modual of some sorts when it gets hot it stops working cools down and will work again its not an O2 sensor Quote Link to comment
hang_510 Posted October 22, 2009 Report Share Posted October 22, 2009 ill have a spare module after KA-Kait picks out what she needs and finds the setup that works. Quote Link to comment
moparvwfreak Posted October 22, 2009 Report Share Posted October 22, 2009 i agree with checking the dizzy. i knwo its not a Datsun, but my jetta ran like a champ and now i cant get it to start. i have checked and the hall effect unit is intermittent at best. i would check the dizzy as well as a fuel pressure test to see if its getting fuel also. Quote Link to comment
sssr20det510 Posted October 22, 2009 Report Share Posted October 22, 2009 check spark im not sure on the z but some vehicles will cut fuel if the dizzy is out Quote Link to comment
bonvo Posted October 23, 2009 Report Share Posted October 23, 2009 i havent seen this mentioned but is it a matchbox style distributor? if it is remove the matchbox and take some emory cloth to the back and screw holes to ensure its getting a good ground Quote Link to comment
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