280zxt driver

hey everybody, I'm new to these forums so please bare with me. so i bought this 1983 datsun 280zx turbo in 2010, It was a barn find. it had sat for at least 12 years considering the plates on it were from 1998>.<. anyways i picked it up for a steal with only 53,000 original miles. I did the standard maintenance, changed all the fluids, slave, master, new bat ect... i did all this and after a few turns she fired right up with no stutter. i replaced the full break system and did everything else that needed to be done to take this baby on the road. she ran great for a few months until the fuel pump went out witch led me to acid bathing the tank because it was full of rust... "nightmare". after i did all this she has ran great up until about a month ago and this one has me stumped, part of the reason is i don't have the time lol so i was hoping someone on these forums will know whats wrong with my Z!!

okay so this is whats happening, car starts fine, idol is normal, i will give it a min to warm up before taking off but it has always been rough driving until its up to temp, like it chokes out and is real choppy.. but its always done that and has ran great after its up to temp, so idk is that's normal for the z or not? well anyways my problem now is whenever i get up to speed or stay at a steady rpm it starts to choke or bog down, roughly between 2500 and 3500 rpm, its weird because if im going down the highway and it starts acting up i can let off the gas quick then excelerate and it will be fine for a little bit then it will happen all over again. it def feels like there is less power. the fuel pressure is fine, injectors all read good, there is new plugs, wires, cap and rotor, fuel filter, fuel pressure regulator, air filter is clean. I'm just stumped, I have been working on cars for years but this one is getting the best of me. now i did talk to another mechanic and he told me to replace my thermo time switch, he thinks its that or my MAS..
If anybody has an idea on whats wrong with my 280zx please comment or PM me, thanks guys!!

280zxt driver

not trying to tell everybody my life story, i just want everyone to know the history, i figure it will make diagnosing the problem a little easier

77280ZX

the more information the better. did yo check all of your electrical connections (MAF injectors TPS CHTS ex...) im also assuming that you have replaced the battery after it had been sitting for so long... from what i hear Z's hate low voltage

FricFrac

I'm assuming since you cleaned the tank out you changed the filter, blew out the lines and cleaned the injectors. Check the AFM and the connections as well as the CHTS. Get the FSM from XenonS130

Welcome to the site

borini63

After confirming a good parts like AFM,Injectors,CHTS,TPS,Clean Gas tank,Fuel filter,clean fuel Lines and there no vacume leaks,Then check out your Fuel Pump especialy the inlet from the gas tank to the pump and also make sure your pump in good working condition is not just buzzing and running but you need to make sure it pump gas good(37PSI at idle).
Happened to me with my last ZXT and it was sitting for a few years.After learking with here for two weeks going through everything then found out that the fuel pump was semi pluged from the inlet by Gung.Cleaned the Pump and wow what a change,no more bogging or stumpelling......runs as it should be.

280zxt driver

yeah i have a new bat, its actually the second one ive put in there because the first battery was from walmart lol... your right they hate low voltage>.<. when I cleaned my tank I did replace the fuel filter and fuel pump. I have recently replaced the fuel pump again "its only a cheap aftermarket one from O'reilly auto parts but I checked the pressure and its between 37 and 42 psi. New fuel filter, plugs, wires, cap and rotor. I did all this when it started acting up, and it does run better then it did but the issue still lingers. once I have the money I will upgrade the fuel pump. i guess the one thing i didn't do is blow out the lines, they are hard lines and im sure there crowded as fu*k, i never did anything with them because the car ran great from 2010 till just recently. I was thinking about just replacing them with soft high pressure fuel lines.
second question. so under the tank is the fuel pump, now just after the fuel pump there looks to be like a secondary fuel pressure regulator, i feel like that may be the issue, since there is already a fuel pressure regulator right on top of the motor next the the fuel rail can i just delete/ remove the one by the fuel pump?
thanks guys!! were going to get this figured out! i love driving this car! its a blast! but let me tell you i hate driving the damn thing when it doesn't run right..

280zxt driver

oh and yes i checked all my electrical connections, di-electric grease on all of them.

FricFrac

Don't put grease on your electrical connectors it's a really bad idea. Yes it will keep water out but the problem is an electrical contact works based on contact surface area with the metal contacts. Grease PREVENTS metal on metal contact and greatly reduces the capability of your connectors.

Did you test the AFM and CHTS with the procedure in the FSM?

280zxt driver

i could be wrong but doesn't di-electric grease increase connectivity? i understand what your saying but I have always been under the impression that that's what this stuff did, I have used it for years and never had any issues

no i didnt get the chance today to test the AFM i will tomorrow hopefully or possibly friday

FricFrac

Dielectric means it doesn't conduct. Using conductive grease would be even worse - you would likely end up with shorts.

Like I said it seems like it works but in reality it compromised the connector. The proper solution is to replace the faulty 30 year old connector.

ThaPimpShrimp

Sounds exactly like my CHTS problem, check that first and check the connector too - mine was bad.

Pamela York

I am having a similar problem. With my 81 Datsun ZXT. I'm worried that the Turbo may be damaged because the exhaust is heated and recirculating to give the turbo boost. The car backfires, pops and loses power. Doesn't stall and starts first try. I only drive it in the summer months because it doesn't handle well on ice and snow so it sits for about 8 months of the year in storage. I worry the Gas tank may have rust. That's what may be clogging the fuel filter.