Justinp551 Posted April 27, 2012 Share Posted April 27, 2012 I have completely rebuilt my 280z- drivetrain engine and all. I have put 2200 trouble free miles without any hiccups and today it starting acting up. Stock electronics with a fresh rebuild l28. Driving up a slight hill today after running at 85mph for 2hrs and all of the sudden it was like the key was turned off. I coasted over to the side and hit the starter and it fired right up and ran through the gears fine. It ran for about the next half mile and just quit again. Cranked for one attempt and tried a second crank and started right up again. It did it about 3-4 more times in the next mile or two till my destination. Its not sputtering but with the first crank it will start then die when i hit the gas. Start it again and it will run normal. Everything looks fine and hooked up. The tsp is not wet or shorting out. I am sure if I sort through the millions of posts of engine dying I might find something but I am a bit tired, not in front of a computer and heading to the z meet in LA sat so I dont have much time. I dont think I missed anything. Look forward to the suggestions. Quote Link to comment Share on other sites More sharing options...
ttodhunter Posted April 27, 2012 Share Posted April 27, 2012 Sounds to me like something wrong with the ECU. I had mine (76) die for no apparent reason, wouldn't fire when cranking. I disconnected the battery for a minute and it fired up and drove like normal. On the ECU I had before this one, the engine would idle, but die if you gave it gas. I was able to pick one up for $20 or so off of Craigslist, or maybe someone on the forum has a spare. Run through the troubleshooting section of the Fuel Injection Bible. Good Luck! Quote Link to comment Share on other sites More sharing options...
neotech84 Posted April 27, 2012 Share Posted April 27, 2012 Yep sounds like an electrical problem. Quote Link to comment Share on other sites More sharing options...
Leon Posted April 27, 2012 Share Posted April 27, 2012 Of course it has to happen right before a long road trip, but hey, at least it didn't happen during! Sounds electrical and possibly heat-related. Ignition module, possibly. Are you using a ZX distributor? Quote Link to comment Share on other sites More sharing options...
Justinp551 Posted April 28, 2012 Author Share Posted April 28, 2012 Thanks for the suggestions. Could have happened after the long trip and I would have been less ticked about it. Haha. Drove it about 25 miles fri and seemed to drove fine. Must just be mentally messing with me. It is the stock dizzy so that's not a issue I hope. I do have a extra 76 ecu that I will bring along with a extra coil and AFM. Hoping I should have it covered for the trek to LA today. Will a 76 ecu work in a 75 car? Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 28, 2012 Share Posted April 28, 2012 Pretty sure the 75 ECU is the same as the 76. There should be part numbers on both. The ignition module could be your problem, they do tend to fail or show that they're failing when hot, apparently. Sometimes high RPM will bring the problem on. I had a module that I could cause to sputter and misfire by revving to over 3500 RPM. Turn the engine off and restart and it would go back to normal. I could drive around all day as long as I kept the RPM low. Quote Link to comment Share on other sites More sharing options...
Leon Posted April 28, 2012 Share Posted April 28, 2012 I believe you can wire in an HEI module in case your factory module fails. The diagram should be around here somewhere. Quote Link to comment Share on other sites More sharing options...
Justinp551 Posted April 29, 2012 Author Share Posted April 29, 2012 Ok so put 150 more trouble free miles on it at 85mph and itbstrts acting up again. Keeping in in gear and turning the key to acc and back on will restate the engine bit it's duration of running gets shorter and shorter till it won't restart. After a few min of sitting it will fire up and run fine. So first thing I swapped was ecu. The 76 ecu ran the 75 car fine for about five min then started the same symptoms again. After it finally failed to restart on the coast mode I pulled over and swapped the coil. Same thing after about another 5 min slowly fades worse and worse. So I can safely say I dont think it's ecu or coil. On the last failed start up it was almost catching like there was a fuel pressure problem. After 3-4 attempts it finally started up and ran fine for the next mile. So here I sit at Starbucks scratching my head. Fuel pump? Would it failing cause such a sudden quit of the engine? No sputtering or surging just it's like the key is turned off. It almost seems like it could be operating time/heat issue. 3-3.5 hours and it starts getting worse and worse. Thur 3hrs and started acting up. Yesterday put 25 miles on it and ran great. Another 20 or so this morning and great. Now I take off for a seven hour drive and 3-3.5 hours into it starts acting up. Hmmm. Well since I won't make it to Z Nationals this weekend looks like I have time to study up the FI bible. Fml! Haha Quote Link to comment Share on other sites More sharing options...
Justinp551 Posted April 29, 2012 Author Share Posted April 29, 2012 Update. After nursing it home for 85 miles this is what I can add. It died repeatable for the first 40 miles. I was shutting it off and coasting down as many hills as I could. I did start to notice a small half second hesitation or power loss just before it quit. Now could this be a fuel pump or relay. Here is the weird thing, after the sun went down and air temp dropped a bit it cruised ran perfect at freeway speed for the last 45 miles. Now could a relay be failing or could the air temp sensor in the AFM be causing a problem? I am kicking my self for not swapping the AFM after the first two item swaps. This would have ruled out the complete AFM assembly as a culprit. So with the last two posts... Any one have any suggestions? it cruise Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 29, 2012 Share Posted April 29, 2012 Sudden death is typical of loss of spark. Ignition module would be next in line after the other things you've tried. The AFM is just a potentiometer, no transistors to overheat. Quote Link to comment Share on other sites More sharing options...
Leon Posted April 30, 2012 Share Posted April 30, 2012 Yes, ignition module is the first thing I'd be looking at, as I mentioned. Wire in an HEI module (hell, they're cheap!) and see what happens. Quote Link to comment Share on other sites More sharing options...
Justinp551 Posted May 6, 2012 Author Share Posted May 6, 2012 Well I swapped another ignition module in and we will see how that works. Had to do a bit of reviewing the wire diagram as my Z is a federal model with dual dist pick ups and seven wires going to the IM verses five for the new one. So far it runs fine but need to take it out for more than a hour and half or so, that's when the old one started quitting. Leon would it be better to run the 79 dizzy vs the HEI module due to removal of the ballast resistor? Or was the HEI option there for a more economical solution? Either way I will run this module for a bit if it works. Thanks everyone for the advice and input. Quote Link to comment Share on other sites More sharing options...
Leon Posted May 7, 2012 Share Posted May 7, 2012 Well I swapped another ignition module in and we will see how that works. Had to do a bit of reviewing the wire diagram as my Z is a federal model with dual dist pick ups and seven wires going to the IM verses five for the new one. So far it runs fine but need to take it out for more than a hour and half or so, that's when the old one started quitting. Leon would it be better to run the 79 dizzy vs the HEI module due to removal of the ballast resistor? Or was the HEI option there for a more economical solution? Either way I will run this module for a bit if it works. Thanks everyone for the advice and input. The HEI is the cheap and proven solution. ZX modules are much more expensive and both options require some wiring work. Quote Link to comment Share on other sites More sharing options...
Justinp551 Posted May 13, 2012 Author Share Posted May 13, 2012 Ok so the saga continues. After putting the new module in the car has been running great for the last 400 miles or so. And a solid 200 mile continuous. Thought I had my problem solve till two days ago. After a short 20 mile drive it started cutting out again. But now it is more reluctant to just fire up and continue. So I put a pressure gauge on the fuel system ran it into the cab. Seems I am loosing fuel pressure. It drops from normal 35ish down below 15 itfill it finally dies. So I am thinking bad fuel pump. Well I swapped it with another one(it's great having a identical complete parts car) and pressure seemed to be fine. I ohmed both pumps for the hell of it and there was a difference. Don't know if that matters at all. Ran great in 90degree heat for 150 mile then bam! Quit again. What's weird is it doesn't just quit as abruptly as before but starts missing, dying as pressure is dropping then finally dies. WTF! So what am I missing here. Stock l28 stock FI Swapped ecu, coil, ignition module, fuel pump and damper, airflow meter and still having problems. Checked the fuel filter and it was clean. Thinking maybe something is floating around in my tank and plugging up the feed line. Notice it happens around just above half tank. So stumble to the gas station, topped it off and a mile later here I sit. Grrrr!! Could the fuel pressure regulator be failing? I wouldnt think I would get the pressure indications but... I am out of options and almost out of parts to replace. Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 13, 2012 Share Posted May 13, 2012 Thinking maybe something is floating around in my tank and plugging up the feed line. ...I am out of options and almost out of parts to replace. These are pretty common (both). Fuel pressure should never get down to 15 psi. Apparently, there is a screen or wire sock around the outlet tube from the tank. Many stories on the forums about flakes of rust or "stuff" floating on to the mesh and clogging it, then floating free after the engine dies. The fuel tank has a drain plug. You might consider disconnecting the hose to the fuel filter, running it in to a gas can or three, and hot wiring your pump (disconnect the starter and hold the key or run a jumper directly the the pump) while you monitor fuel pressure as the pump drains the tank. Then shake the car around to stir up the residue and remove the drain plug. You'll get a look at what happens to fuel pressure over many gallons of fuel, and you'll see what's sloshing around in the tank at the end. Quote Link to comment Share on other sites More sharing options...
Justinp551 Posted May 18, 2012 Author Share Posted May 18, 2012 The damn saga continues... so after putting another 400 miles on the car last few days it has been running fine-again. Still questioning whether there is something floating around in my gas tank so yesterday I pulled the tank and did a thorough inspection on it. I used a boroscope and flashlight and had the fuel sender out and was able to look just about everywhere inside the tank. Other than a small bit of rust flakes that came out of the drain, there was nothing that I found. I turned it up side down, on its side, every which way I could to see if something was moving around and it all seemed to check out fine. So I installed a few new vent lines that were cracked while I was at it and made sure everything was correct. Put it all together, ran great and started the 200mile drive back to San Fran. Just a bit above half tank and about 20miles from home the damn gremlins showed up again. Just died like the ignition was turned off. I turned it off and on and it started right back up and ran normal on the freeway for about the next 5 miles. Then it happened again. Had to sit for a few minutes and then ran fine again. Happened about 5-7 more times and finally made it home. I crawled underneath and felt the fuel delivery line to the fuel pump and it didn't seem collapsed. Also popped the fuel cap and didn't hear a vacuum or anything strange. And of course it started right up this morning and got me to work no problem. So what am I left to check? As stated in previous post it seems its a fuel pressure/delivery problem as indicated by falling fuel pressure. When/if a pressure regulator acts up what are its symptoms? Will it just fail black and white or will it sometimes partially fail? Also is there possible a fuel pump relay that is going bad and disconnecting and when it cools or I turn the car off and back on it eventually work for a bit longer? Quote Link to comment Share on other sites More sharing options...
dexter72 Posted May 19, 2012 Share Posted May 19, 2012 Did you check the screen in the fuel pump?. If it has some of the rust particles caught in the screen that is the problem. To help filter the rust from the tank, Try adding one of those glass inline fuel filters in the line before the pump. That way you can catch and see everything that is coming out of the tank. Should keep the pump screens from getting clogged up also. But i also had something in my tank that would only let my engine rev to 3000rpm. I pulled the drain plug from my tank and fuel only trickled out of it. I blew compressed air into the drain plug hole and after that fuel came gushing out of the hole. After draining the tank i used a magnet and got the rust out of the tank. Engine revved normally after doing that. Quote Link to comment Share on other sites More sharing options...
Justinp551 Posted May 19, 2012 Author Share Posted May 19, 2012 Thanks for the input. After sitting on the side of the road again last night, I did some more reading in the efi bible. Found the section on the FI relay. So for a stab in the dark(no pun intended) I reached down and felt for the relay harness and wiggled some stuff down there. To my surprise the damn car fired up and drove for the last 15 miles home trouble free. Thinking maybe it has a bit of corrosion or maybe was a bit loose. Either way I will be giving it more attention in the light and making sure it's clean and tightly connected. Fingers crossed!! Quote Link to comment Share on other sites More sharing options...
Buck Wild Posted June 11, 2012 Share Posted June 11, 2012 I have completely rebuilt my 280z- drivetrain engine and all. I have put 2200 trouble free miles without any hiccups and today it starting acting up. Stock electronics with a fresh rebuild l28. Driving up a slight hill today after running at 85mph for 2hrs and all of the sudden it was like the key was turned off. I coasted over to the side and hit the starter and it fired right up and ran through the gears fine. It ran for about the next half mile and just quit again. Cranked for one attempt and tried a second crank and started right up again. It did it about 3-4 more times in the next mile or two till my destination. Its not sputtering but with the first crank it will start then die when i hit the gas. Start it again and it will run normal. Everything looks fine and hooked up. The tsp is not wet or shorting out. I am sure if I sort through the millions of posts of engine dying I might find something but I am a bit tired, not in front of a computer and heading to the z meet in LA sat so I dont have much time. I dont think I missed anything. Look forward to the suggestions. Quote Link to comment Share on other sites More sharing options...
Buck Wild Posted June 11, 2012 Share Posted June 11, 2012 Check your air gap between the stator and reluctor. Had the same problem and this was what was wrong with mine. Quote Link to comment Share on other sites More sharing options...
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