vangsnet

Hello!

I am a new Z31 owner two weeks ago. I bought a 1986 300zx non-turbo 2 seater not running. It is an automatic. Previous owner stated that it was parked for 6+ month and then now it just won't stay running. It was working before parked. I trailer it home and was able to get it to fire up when prime. But it stalled after 5-10 seconds of running then rpm drop down and shake like it's not getting fuel then stall. If I tried to give gas, it will stall right away. Will not start if not prime. Will run with fuel spray into the TB until ran out.

T-shoot done:
1. Fuel pressure test
2. Spark test
3. Fuel injector test
4. TPS test
5. No AC belt - not fixing at this time.


Things I replaced:
1. New fuel pump
2. New spark plug
3. New IAC
4. New pressure regulator/temperature sender sensor
5. Swap TPS with another use one
6. New fuel pump relay
7. New fuel filter
8. New relay for vaccum (was missing)
9. New fuel pump fuse

Self Diagnostic:

1. code 23
2. code 31

Please help shed some light. Thank you!

zxguy1986

Welcome to ZDriver!

Check out the two solenoids on your air regulator. They get tired after 25 years. Take them out and power them with your circuit tester. You can hear and feel the click action in your hand if they are still good. The idle-up one could cause her not to idle at all.

Also check and clean all the harness connectors leading to and from. They get dirty and corrode.

vangsnet

Air regulator was replaced with a brand new OEM one as mentioned above. Connector is clean and wire looks good. New blue and green fuel pump relay. Still start and stall like before.

zxguy1986

I take it you have the factory service manual there. Your list says you replaced "pressure regulator," meaning the part called that on EF&EC-10 of your FSM? The air regulator is hanging on the right side of your plenum and looks just like the one on EF&EC-18 'SEF130C'. Those solenoids are what I think you should check out. I doubt you found a 'brand new OEM' air reg. To replace one solenoid I had to buy a whole recycled unit. Worth it to get the air reg back in the game tho.

vangsnet

Where can I download the FSM? Sorry, I replaced the fuel pressure regulator and Idle Air Control valve (IAC). Will look into the two solenoids. Do I just take them off and clean them and put back or do I actually have to replace them. I'm leaning toward cleaning because I was told by a mechanic(friends of my co-worker) to replace the above but it did not fix my issue.

zxguy1986

Easy. Free download at XenonZ31 Reference Get the fiches and the other stuff too.

I am impressed that you did all that work without needing a manual, so you must know what you're doing. Anyway, at this point you are more making up for regular maintenance the previous owners did not do for a long time. Then a small part is simply replacing parts that have finally worn out. My idle-up solenoid worked perfectly for 27 years before it gave up. I had to locate a whole air regulator to find a replacement. You do that by sending a foto of the regulator to a recycler who has a Z31 on the lot, tell him where on the motor to look, and tell him you want the solenoids. He'll want you to buy the whole regulator. I paid $40 and drove there to pick it up. Both solenoids worked like new.

Some of what you're doing is really throwing parts at the car without hitting the problem. That's sort of unavoidable with new Z owners. Don't worry about it. When you get it running you will be amazed at how reliable and constant the car is. Starts perfectly and runs right every time. They make great daily drivers. The amazing design and excellent part reliability make it possible to get 'like new' performance from a 30-yr old Z. Pretty amazing.

So you take the solenoids out, hold them in your hand, power their circuit at the connector with a tester and feel and hear the click of it working. No click, replace it. If you can get the orig part number from the fiches, check with the orig Nissan parts places, your dealer, and aftermarket. If not available new I would use Car-Part.com--Used Auto Parts Market to locate a dead Z31 ('84-'89) on the lot somewhere. Sort the search results by distance from your zip code and search for a common part that recyclers typically do not remove from the car and shelve, like motor or radiator, etc. Call their 800 number and ask if the car is on the lot and send a foto of the regulator. Say you need one with both solenoids. They're out there. The second one is the fast-idle control device. Both need to work if the car is to idle correctly, 500-700 rpm warm, maybe 1200 cold. Z31s vary a little.

If it isn't a solenoid, there are a lot of other things to check so report back. Rogerz and others here will give you their rundown lists of basic maintenance catch-up stuff to check out on a Z31. Don't worry. That Z will run perfectly again and all your work will pay you back big time. A well-maintained Z31 is a miracle.

vangsnet

Thank you very much for all the advices. I did downloaded the FSM and will take some times reading it. I will take out the solenoids to test. I may also drop the timing cover to check timing. I will update back as soon as I get sometime to test it and what I found as I continuing working on the car.

rogerz

what relay are you calling the vacuum relay?. what was your fuel pressure reading? what is a spark test? did you see spark or did you time the engine with a timing light?

vangsnet

Update: Take top timing cover off and left cam timing mark match when TDC, but right side off by about a tooth out. Count number of teeth and it was 40 teeth between both cam mark. Timing belt seem to be stretch. Look down on harmonic balancer and mark doesn't match. It's an inch pass the 30 degree mark. I've decided to drop bottom timing cover to check. Looks like bottom timing mark match too, but timing belt not tight so belt must be stretch over the years. I went to Oreilly's and they have the parts at their warehouse so I drop by their warehouse to pick up. I've replaced timing belt, tensioner, water pump, thermostat, cam seal, crank seal and all the belt. After 10 hours working on it, finally done. But it still start when prime and run for 5-10 seconds and die. Too tired so will continuing tackle it another day.

vangsnet

Rogerz,


Have not check fuel pressure since I replaced the fuel pump. Couldn't rent it because someone rent it and has not return it. I pulled out the spark plug and have someone crank it while I ground the spark plug to the block to verify there are sparks. All cylinder seem to have good sparks.

rogerz

you are obviously not very good mechanically. you can't seem to understand the difference between valve timing and ignition timing. Buy an oil pressure gage for like 10 bucks or less plus some fuel tubing and a few fittings. you put the gage between the fuel filter and the fuel ring. just because a gage says oil pressure doesn't mean it can't measure fuel or oil or water or any other liquid pressure. If you get a gage with some 1/8 plastic tubing for hookup you can run it up by the wiper blade and close the hood. you can then drive around the block SLOWLY and watch your fuel pressure. A bad fpr will affect engine operation negatively.

vangsnet

Update: Finally have some times to hotwire the fuel pump (20Amp inline fuse on the battery positive) and finally got the car run for the first time(without stalling). Take it for a spin around the neighborhood and it run really good. I didn't expect it to run this nice especially when I bought it not running and without even test drive it. Everything work on the car except for stereo and AC. When I bought it, the AC belt was missing so I didn't want to turn it on yet. Exhaust a bit loud, but no other funny noise while driving. Brake need a little adjustment, but stop good. Going to clean up the engine and do a final inspection before taking her to the highway.


After taking the car for a spin, I took out the rear carpet and accessories and check all wires. Trace it back to the backseat with no break. Check the passenger floor and didn't see anything either. Finally take out the ECU and crack it open. At first, I didn't see anything but upon close inspection, I found that there are two transistor that bot burned on the leg. Will have to buy another ECU, but in the mean time, will run a switch to turn off the fuel pump.


Thanks to rogerz and zxguy1986 for the help. Seeing your encouragement, give me more patient and more strength to work on the car. Will take her to get a good bath and detail this weekend. Can't wait to take her out this weekend!!!