jas280z Posted July 11, 2011 Share Posted July 11, 2011 My 280z won't start when it is hot after a drive. I am very familiar with heat soak, having experienced it last summer. Then my car would not start when hot, after sitting for a few minutes. I installed a switch on the starter solenoid, to allow me to manually prime the pump/fuel rail, and voila I was able to start no matter how hot the engine got. My symptoms now do not seem to fit with heat soak, as the car does not need to sit at all for the problem to occur. I turn it off and try to start it 1 second later and it will not start. The only time when I was able to get it to restart was when I instantly restarted it before the engine had even stopped spinning. I am able to start the car if I spray some starter fluid into the intake manifold, and initially get it running on that. Then the car will start, but obviously stumble a bit at the beginning. This leads me to think that the fuel is fine, and not vaporizing. Just for further information, I also have constant 30+ psi at the rail while I am trying this. Due to the fact that the car can start on starter fluid and then run, I think that something electrical that is only engaged in the "start" circuit may be overheating and failing. One thing that comes to mind is that maybe the Fuel Pump Control Relay is not functioning correctly, as it receives its 12 volt signal through a different input on the start cycle (I believe this is to bypass the Oil Pressure Sending Unit kill switch when starting). The power then goes out to the fuel pump relay, and to the pump and the air regulator. I have tried testing the Fuel Pump Control Relay according to the FSM, and could not get it to test out right, but that was before this problem arose, so I attributed it to an error on my part, or an incorrect procedure being listed in the FSM, as I found the problem I was having at the time, and it was not related to the relay. One test I can attempt would be to hot wire the fuel pump to see if it will start when hot, but I am not sure if the injectors are firing correctly either. I still have to test them with a noid light. All that I am fairly sure of is that it is something screwed up/overheating in the start circuit. I am studying the FSM and wiring diagrams, and also getting what I can from Blue's Tech Tip EFI Bible, so I am sure that if it is something electrical I will find it sooner or later, but any suggestion that could expedite the process would be greatly appreciated. P.S. I did try starting it with the cold start valve disconnected, and still had the same problem. Unfortunately I don't think it is anything as simple as that. Quote Link to comment Share on other sites More sharing options...
RangerWill Posted March 7, 2013 Share Posted March 7, 2013 Similar issue here as well. 77 280z w/a few engine mods and deletes. I also thought to run a hot switch to the fuel pump and did. Fixed nothing. I have to run the starter for at least 20 seconds to get it to fire up while the motor is hot. With the engine cold it fires right up. Just a couple turns of the starter. I'm at a loss. Someone help us please!!!!!!!! Haha. Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted March 7, 2013 Share Posted March 7, 2013 Check the water temp sensor. Resistance could be off. It triggers the cold start enrichment. Just a guess. Quote Link to comment Share on other sites More sharing options...
Rob L Posted August 11, 2015 Share Posted August 11, 2015 (edited) I will add to this since nobody has really responded or maybe hardly anybody gets this problem because i have done many searches and only links to the LS guys show up concerning this.BUT i have this problem as well !! On an L6 . I have a new battery ...new cables ....and i bought a new starter.Now the starter works great its a gear reduction unit and is smaller and lighter then the original.......my car starts no problem when its cold and every single time.....even a 15 minute drive and it will still start....BUT if i really heat the engine bay up i.e. hour drive or really hot hot day after i shut the car off if i immediately go to start it nothing happens ...if i wait 5 to 10 minutes and let it cool down it starts.....So this problem we are having could it be a relay of some sort. Edited September 1, 2015 by theatriks Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 11, 2015 Share Posted August 11, 2015 i shut the car off if i immediately go to start it nothing happens ...if i wait 5 to 10 minutes and let it cool down it starts.....So this problem we are having if its anything like mine ...theres a chance its the starter. "go to start it nothing happens" means turn the key to Start but the starter does not work? The engine does not turn over, the starter does not even click? Or something else? Quote Link to comment Share on other sites More sharing options...
Rob L Posted August 12, 2015 Share Posted August 12, 2015 ^^^ it does nothing, i will pay more attention to see if it actually makes a clicking noise ....i will wait maybe 10 minutes and it will fire .....and it acts this way everytime its hot .....never any trouble starting it first shot when its cold. Quote Link to comment Share on other sites More sharing options...
Rob L Posted August 18, 2015 Share Posted August 18, 2015 (edited) So I got the chance to spend time with my car today ...got in it and it started right up like a brand new car ....drive for 30 minutes went back home to the garage . Tried to start it now that it was hot and..... @ new zed ......It's confirmed its a click I get .....at first then I went back outside tried it again and I was getting nothing ...but it's an extremely hot day here ...we got a heat warning . Edited August 18, 2015 by theatriks Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 18, 2015 Share Posted August 18, 2015 Find out where the click comes from. Put a meter on the starter terminals and see if the starter is getting voltage. You'll need to think about the difference between the solenoid and the starter motor itself to figure out if the solenoid and starter are getting proper voltage, but not working, or if they're just not getting battery power. Quote Link to comment Share on other sites More sharing options...
JSM Posted August 19, 2015 Share Posted August 19, 2015 I would think in this situation when it is hot you can remove the starter wire to the solenoid, jump It with a screw driver to allow you to start it. Quote Link to comment Share on other sites More sharing options...
Rob L Posted August 19, 2015 Share Posted August 19, 2015 (edited) i got a click and it sounded like it came from the starter ....I will try out what you said ...but after I got the click I tried again and got nothing and then I lost even the door chime when I put the key in . I then went inside ate dinner. Car had a chance to cool down . Went to start it and it started right up ...I'm talking like instantly not even a hesitation ...love it ! Edited August 19, 2015 by theatriks Quote Link to comment Share on other sites More sharing options...
JSM Posted August 21, 2015 Share Posted August 21, 2015 Just don't forget to make sure it is out of gear! Quote Link to comment Share on other sites More sharing options...
Rob L Posted September 1, 2015 Share Posted September 1, 2015 OK so i put the old starter back in my car and im still having the same problem .......started no problem today cold....drove it to work ...shut it off immediately.....tried to start it back up right away ....and nothing ....no fuel pump.....no click ...no door chime ...nothing! its acting like there was no battery in the car i..........tried 20 minutes later and still nothing!!!.....am i the only one who has had this type of problem before? im at a loss ....is there a relay that can be acting up when it gets hot ?....anything along those lines? Quote Link to comment Share on other sites More sharing options...
Rob L Posted September 1, 2015 Share Posted September 1, 2015 so after my above post ...35 minutes later...after cool down ...the car got all power back and started right up !!!.....anybody have this issue before ?. Quote Link to comment Share on other sites More sharing options...
JSM Posted September 3, 2015 Share Posted September 3, 2015 (edited) Man that is weird. I wonder if your fusible links are going bad and the heat from the engine is causing them to lose continuity? For the heck of it when it gets hot like this and wont start, bring a voltmeter with you and check all four links to make sure they are still showing continuity. When I had my 280z I re did my similar to these: Edited September 3, 2015 by JSM Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 3, 2015 Share Posted September 3, 2015 If you don't have a meter, a test light will do. Anything besides just turning the key and wiggling wires. Measure the power paths (aka crcuits) and see where the break is. First confirm battery voltage across the posts themselves. Then across the cable terminals attached to the posts. Then the cable ends at the starter. Starter lug to engine block. Starter lug to body panel. Things like that. You're not even using the most basic troubleshooting method. Quote Link to comment Share on other sites More sharing options...
Rob L Posted September 16, 2015 Share Posted September 16, 2015 (edited) Ok so it turns out it was a fuse in my fusible link box this whole time .... now to figure out whats melting this guy....ive started by buying a new fuse holder and fuse and see how quickly it happens again ....im wondering if its the new starter i put in ...because thats the only change ive made along with a new coil . Edited September 16, 2015 by theatriks Quote Link to comment Share on other sites More sharing options...
JSM Posted September 16, 2015 Share Posted September 16, 2015 Yeah!!! Quote Link to comment Share on other sites More sharing options...
Rob L Posted September 16, 2015 Share Posted September 16, 2015 Yeah for real lol ......finally found the problem !!! now that summer is almost over lol Quote Link to comment Share on other sites More sharing options...
cgsheen Posted September 23, 2015 Share Posted September 23, 2015 Thank Goodness Summer is almost over!!! Quote Link to comment Share on other sites More sharing options...
mikexfctr Posted December 25, 2022 Share Posted December 25, 2022 Most times this problem is caused by a faulty resister pack that is attached to the distributer right below the cap on the side. It's black and attached with 2 screws. It used to cost like 250 bucks new from the dealer. Replace that and your car will be ready for the races!!! This is a common issue as a lot of those resisters are not resistant to heat - at least the first generation ones. Wish all of u good luck and Merry Xmas. Quote Link to comment Share on other sites More sharing options...
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