Z31 Starting Problems
 

Hey guys first post, I would some advice on how to fix this issue with my car.

Ok long story short. My car is turning over but not actually starting.

The fuel pump is working. I am getting fuel to the fuel rails The distributor looks fine as well. The car is getting spark.

Past few weeks the car will start fine then maybe every other week it will start shuddering and surging with i am driving. I get a really rich smell coming from the engine. Black smoke comes from the exhaust and it wont idle. If i hold the rpm's at 3,000 it will drop to like 600 then back to 3,000 then back to 800. Once it dies it will not restart until i leave it alone for a day or two then it works fine for a few weeks.

I have ran Diagnostics and i have gotten codes 13,14

So far all i can think is that either my ECU is bad maybe my MAF?I have not checked the injectors or the spark plugs yet.

I would love any help guys its starting to bug me. If you guys have any more questions let me know.

Thanks in advance

Well your regulator on your alt. Might be going bad. Had a similar issue with another one of my cars not too long ago. I also had problems with my ignition coil but the thing with that is it wouldn't turn over at all. So since yours 'is' turning over I doubt.

replace the O two sensor and chts. No guarantee but since it runs they are two things that cause weird symptoms. what is your fuel pressure? A bad fpr can cause weird things also. here is some good advice:
Get your battery load tested. Be sure you have clean, tight corrosion free terminals on both ends of your battery cables. Be sure the ground (negative) cable goes to a bolt into the frame before going to the starter. grounding through the starter is not a reliable connection. Z's don't like low voltage. causes the electronics to act funny. it is possible to have enough amps to crank but not enough voltage to run the electronics. If you have one size fit all cheapo clamp on terminals they are a problem waiting to happen.

Clean the connectors for the maf or afm, ecu and tps. Deoxit by CAIG is probably the best connector cleaner on the market. spray with CorrosionX after cleaning and before putting together this will help prevent any further corrosion.

Update time:

Thanks for the tip guys but so far i have nothing.

When i started it this morning after sitting a week it started up instantly for 5-10 mins then it would not start again.

It is getting spark to the spark plugs, Fuel pump is working, and the relay is good.

I cleaned all my connectors and cleaned the MAF, and replaced every vacuum line in my engine. we tested the crank angle sensor and it seems good as well.

The only conclusion that im coming to is either the chts or ECU. Can a bad chts keep it from starting?

When i removed my ECU and opened it up, the left side of the circuit board appears to be burned out.

should i replace my chts or ecu?

thanks in advance

If your ecu is burned out it kinda goes without saying replace it. Especially since the ecu is basically your cars 'brain'.

What happen to you seems like it happend to me. My z31 started again after i changed the distributor as i thought it was the fuel pump and pretty much everything else it just happened to be the distributor.

I just bought an '85 Z31. I was told by a mechanic that there is some sort of fuel pressure regulator under the battery box. True? I'll find out....

That's how my engine acted as my Fuel Pressure Regulator took a crap. Reg may be letting too much pressure go by flooding the engine.

Okay im having the exact same problem i already cleaned my mafs and had bought a ecu but never put it in because i took my mechanic friend and he kinda fixed it but not really well the problems back and now im wondering if i should get that fuel pressure regulator but dont know were to start on how to put it in if anyone could take a picture or make a short video that would help . Im also going to replace all my gaskets i thought it might help and was needed due to a small leak but since its so hard to get to one so im just going to go for all of them. Advise!!! :026:

when you guys going to learn you need to KNOW the pressure on the fuel rail. a guess that the pump is running tells you squat. this will also let you know if the fpr is bad. maf seldom go bad unless someone sticks a screwdriver in there. take the tin off the front of the engine easiest way to get at the fpr. you can do it otherwise but tricky and frustrating. also with tin off you can check the condition of your timing belt and easily replace the chts.
check your timing and put a vacuum gage in there to see what is going on. otherwise listen to the guy who doesn't have a clue and throw parts and money at it. sometimes you get lucky. fpr not under the battery atop the front of the engine. put that mechanic name in the idiots for hire folder. fpr held on by two bolts you need a video for that?

Update: In my situation it was the ECU.

Fixed the issues right away