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1983 280zx fresh engine rebuild will not stay running

3234 Views 25 Replies 6 Participants Last post by  pdx280
I am a new member, but I have used this sight several time in the passed month researching engine mods. With the rebuild complete someone PLEASE help me. I have an 83 280zx N/A. It has been sitting up for 15 years. Just got finished with a total engine rebuild. All components are original, however I installed a new coil, headers, and a rebuilt P90 head. I also removed and blocked off EGR valve. The car will start for a second or two, but will not stay running. The coil remains energized with fire to the plugs. I have checked the ECU terminals along with the components and all checks out ok as per the factory service manual. For some reason the injectors only energize one time when the key goes to the start position. With the crank angle sensor telling the ECU when to energize the injectors, is there a specific method to installing the distributor?
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put a fuel pressure gage on it. perhaps your fuel pump is not staying energized after starting. Starts and runs briefly means you have the fire and air parts needed to run but are lacking the fuel element after a brief run period. pic attached of cheap fuel pressure checker you can make for under $20 or spend the $30-40 for a store bought unit


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Fuel pressure is good and pump does stay running. That was the first thing I checked. I found this morning that the primary injectors are not energizing at all. The only injector that is energizing is the cold start. Which explains why it will only run for a second or two. I have voltage to the primary injector connectors while grounding to the body. However no ground is being sent/pulsed to the injector connector during start up or while its briefly running. Any suggestions? Is there a way to check the ECU to see if its sending the ground to energize the injectors?
get the fsm from xenon and READ IT. get the fuel injection bible. lots of good info. not specific to the s130 but a very good guide to how nissan does FI. clean connectors for the tps, ecu, chts and afm.
I have both and have studied both for quite some time prior to posting on here. Unless I'm overlooking something. I have ran all the diagnostics. I have checked injector voltage from the ECU connector (terminals 2-8) all are good. All ECU connector ground circuits test are fine. I have voltage at the injector connectors as well. Injectors their selfs all have the same continuity. For some reason the injectors are not pulsing.
On the early EFI Zs the ECU triggers off of the pulse from the negative terminal of the coil. A wire runs from the negative post through the tachometer on to Pin 1 on the ECU. The diagram on Page 7 of the EF & EC section of the 1983 FSM suggests that something similar happens for the 1983 system. My 1976 and a 1978 that I had would not run with the tachometer removed.

You mentioned the CAS as telling the ECU when to fire but the page 7 diagram suggests it is actually the neg. post from the coil. There is no mention of the CAS.

Edit - actually the picture on Page 8 shows the CAS and the coil negative working together. I didn't get in to the details, but it would be worth figuring out where that trigger comes from.

Find out how for sure how the ECU/ECM gets its signal.
Thats interesting and enlightening, beings that I did replace the original coil with a new high output coil. I wonder if I may have a defective coil. As Odie mentioned in an earlier post, I think the CAS were installed on the turbos only in 83, so one less component eliminate I guess. Thanks for bringing this to my attention. I have not given any attention to the coil due to the issue being fuel delivery. Thanks for the lead.
Where are you? Someone may be nearby and you may lure them out with beer or steaks on the bbq. Cheap price to get the engine running, no?
From central Louisiana and I drink and BBQ very well!!
OK.. After reading another post, I took the advice of fellow ZCAR member and shorted the injector connections at the ECU plug (terminals 1-8). And just as he said the injectors began to energize. I did this by taking a jumper wire grounding one end to the body and quickly bumping the terminals. Sure enough each time I bumped the ground on the terminal the injectors would energize louder and louder. I did all of the injectors several times ensuring each one was "clicking". Started the car and she came to life sounding like a beast. She ran great for about 3-4 minutes then died again and would not start. Im thinking one of the temp switches. I have not messed with it since, due to my wife threatening to divorce me if I didn't spend some time with her. I plan on slipping away today to do a little troubleshooting. Anyone have any suggestions?
I have not..Thank you sir!!!
Thank BLUE
The temp switches just affect the length of time that the injectors stay open per each crankshaft revolution. The injectors don't stay open, they just pulse open and closed, when the ECU grounds the circuit.

You've shown that you have power to the injectors and that they will supply fuel when grounded. You still need to figure out why the ECU is not supplying the ground circuit.
The ECU is and apparently has been pulsing the ground required to energize the injectors this whole time. When I made this conclusion in an earlier post, I guess I was wrong. I did not have a light on hand and assumed I could check for pulse with a digital Fluke set to the lowest voltage. Out of desperation I manually grounded the injectors as I mentioned above. They obviously were stuck, because after doing this the car started and ran fine until it warmed up. I have not determined whether it is fire or fuel delivery yet due to the wifes anger. With that being said, what sensor (if bad) would kill either once the car warms up?
My mistake, I didn't catch the 3 - 4 minutes running part in the last post. I think that yours is the second account I've read of the injectors getting "stuck" closed.

Have you started it cold again since then, to confirm it's a cold/warm problem? The ECU uses the water temperature sensor to reduce fuel enrichment as the engine warms up.. If it dies because it's over-rich, that could be the problem. It always helps to reproduce a problem like that to make sure you're working on the right thing. Maybe you just ran out of gas?
The cars at my buddies shop. I had him crank it a few minutes ago and the same thing... It cranked and ran great for about 3-4 minutes then died. He said just like yesterday, it would not restart. Im going to shoot over there shortly and try cleaning all the electrical connections. When it runs for those few minutes it revs great and sounds real strong. It idols smooth as well.
Ignition module,the black square box stuck on the distributor .Did you check it?
I'm still getting fire to the plugs.
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