Aeleven

Im having the same Issue. Ive changed out almost everything.

DatsunZ78

Alright I'm new to the ZX scene, but I am currently going to automotive school to become a tech. If it is a fuel issue, and your uncertain on whether you have enough pressure. You could trying pulled off the intake to the throttle plate and spraying carb cleaner into it for a few seconds and try starting it up. I've seen people try it on engines before they buy them to make sure they run (carb cleaner is literally fuel lol).
On modern vehicles, for rough idling or lack of start. We check 02 sensors, MAF, IAC, leaks in the intake system, CKP, CMP.
Poor fuel economy goes off the ECT (engine coolant temp) so anything based of those and what a OBD1 uses would be your first check on your vehicle. IF all that is good.
I would say it's your ECU. Because if no fault codes are coming up (Again I could be thinking OBDII) Then your ECU is done for if it's not getting a check engine light/ or whatever the ZX version of a CEL.

borini63

Chts!!

farqyj

Just a question because reading through the thread, it is not clear what is going on with your fuel pump(s):
1. Was the old fuel pump removed and replaced with a new, or aftermarket, or used pump?
2. Is there two pumps currently on the fuel system?
3. If so, are they in series (somehow one is feeding the second?) or parallel (both in the tank at the same time feeding fuel to the same line to the engine?)???
4. Have you managed to get any sort of measure of fuel pressure?
5. Have you removed a spark plug and crank the engine? The compression should send a fine mist of fuel spraying up the spark plug hole, which can be a good indication of whether your injectors are working.
6. Having removed the fuel rail recently on mine, I know what a pain it is, but consider pulling the whole rail, aim it at a pile of rags, and crank the engine, and check the spray from the injectors.

My concern is mainly with the two pump issues: if they are in series but one pump is a dud, it will act as a drag on the second pump, causing premature failure. If they are in parallel and one is a dud, it will possibly allow the pressure to flow backwards through it, making the second work harder to achieve proper pressure, also causing premature failure.

Aeleven

I jumpered the connector on my CHTS sensor and the problem went away. I replace the sensor and found out that the connector is bad. Right now I have it jumpered and it runs well, I ll have order a new connector, I believe its the same type of connector that on the fuel injectors.