please help, son home from college

son has 1996 NA slick roof 5spd. Car only has 78000 miles. while driving home today he said car felt like it was losing power. this was after hard accel to merge. While hitting throttle it would either not want to accel and then start. this was on interstate. when he got off the interstate he said car would jerk at every stop. had to take out of gear or would jerk and stall. he said once he got going car would surge on and off especially in higher gears. he also said he could hear a noise from behind seats. I've been working on crap my whole life but not familiar with normal Z issues. I'm thinking fuel pump bc of the noise. Fuel tank maybe 1/4 full when this happened. please help. He has to go back to school Sunday night. You can text me at 985-640-0023.

also the check engine light came on. I tried my scanner but returns no codes. lastly when he just started the car the idle was surging up and down a bit

also, he just said that the noise from behind his head would happen once his foot was on the gas then stop once his foot was off the gas

I always fall back to the 6P when I have issues with my Z32 once I confirm all my connectors are corrosion free and connected properly.

http://twinturbo.net/nissan/300zx/forum ... ncegt.html

Pull the codes form the ECU. The issue described can have too many culprits to blindly shoot in the dark. Codes should give you the best possible insight. If no codes then check fuel pressure and state of plugs, if you have experience with cars you'll be able to tell if its a rich/lean condition by looking at them.

Being a '96 it is obd2 so I pulled codes. Scanner shows no codes. i will go ahead and check plugs. We bought the car in Jan 2018 with 47,000 miles. It is still under 80,000 miles. The car got a major service not long before we bought it. The previous owner had iridium plugs installed with that service. The main reason I went with the pump is due to the noise my son said was coming from behind his head where the fuel pump is. the car was in really good shape when we bought it and was well cared for in its previous life. The p.o. is a retired lawyer east of Oakland and only drove the car on weekends but had knee and hip issues so he sold the car.

Not sure if the 96s have the feature to use the CEL to give you the stored code but you can check the FSM (take a look in the link in my signature). The OBDI ECUs had a knob on the ECU itself that would make switch the ECU to display the code with a small LED on the ECU and the CEL on the dash. The OBD2 codes that a standard code reader will pull are emissions related only so if there are some non emissions codes stored you'd need consult or possibly the old fashioned method (if it works for the OBD2 cars). A fuel pump is a possible culprit but so are a CAS, TPS, MAF, bad injector, etc. The list goes on and on. Make sure it has the correct iridium plugs, though likely not the culprit of your current issue, the VG30s require a long plug (will be listed in the FSM). You can try unplugging your MAF and TPS separately and see what the effect is. Again I've never had a chance to mess with the OBD2 Z32s so I don't know if it'll behave like the OBD1 cars do when unplugging these. The FSM has a great troubleshooting guide.

Ok, Ill look into those things. I know the p.o. always had his local Nissan dealer service the car. He had the plugs, fluids, timing belt, water pump, etc done all at the same time as well as trans and diff serviced. Had to search a lil to find the obd2 plug as it isn't mounted like newer cars. The plug is tucked up in the driver foot well to the side surrounded by a bunch of other wires and crap.

Taking a Z32 to a dealer now days (and actually always) has been a crap chute, its a fairly limited production, high performance, GT car that some of those techs have never even seen before (and half of them were born after the car exited production). That's beside the point though. Take a look at the FSM and the condition of the plugs, if you have a pressure gauge laying around, T it into the fuel line at the filter on the driver side fender run it to the windshield and go for a ride.

NolimitZ32 wrote: ↑

Tue Mar 02, 2021 2:02 pm

Taking a Z32 to a dealer now days (and actually always) has been a crap chute, its a fairly limited production, high performance, GT car that some of those techs have never even seen before (and half of them were born after the car exited production).

Ain't that the truth! I have to give half of these young bucks basic instruction about how a distributor works, most of them have never seen one.

I'm an MR2 guy myself. Drove a 1st gen for over 20 years. The Z32 is a very different beast. It is my son's baby, he absolutely loves the car. I never too my MR2s to dealerships or even private mechanics and most likely will never take this Z to one either. We are actually the 4th owners, we think. The 1st ownership looked like it was a lease but for a very short time so we aren't even real sure. The a guy owned it for a couple years but his wife made him sell it after she had to park in the rain a few times. The parked under their apartment building. The the p.o. owned it the longest and had it from under 20,000 miles to 47,000 when we bought it. It was garage or car port kept its entire life til we got it. Now unfortunately my son has it at MS State so it is always outside. It doesn't get a lot of miles. Most miles are back and forth to home with is 280 miles. He plans on keeping this car for life so once he graduates college it will get more love.

I did change the fuel filter. Filter was full of fuel and fuel looked really clean. Filter had a 2010 manufactured date on it but probably less that 40,000 miles on it. Not sure how many miles the p.o. put on that filter. When I pulled the old pump the lines were definitely pressurized to a point. Car hadn't been driven in a day when I pulled the pump

Is the car is auto? By your comment about taking it out of gear I want to assume so but I've never heard of an Auto Slicktop in North America. If so this may be a torque converter issue. If manual then could the issue be with the brake being pressed and not the car being in gear. With a big enough leak in the brake booster you could be swallowing so much air that its running the car lean and going into limp mode (again not sure how sophisticated the OBD2s got).

car is a stick. He said took it out of gear. not sure if he actually did or just hit the clutch. fuel pump not coming til tomorrow now so will have to go another day

ok, replaced pump tonight. took it for a drive pushing it pretty good through the gears with no issues, so far. son said it started acting up after running to redline in 1st and 2nd so I'll take it back out tomorrow for another "spirited" drive. crossing fingers that it is only the pump

If you have an AutoZone nearby I'd recommend you go get one of the cheap mechanical fuel pressure gauges and T it in so you can keep and eye on the fuel pressure during your drive. Run it under the windshield wiper and tape it to the windshield with some painters tape for the test drive.

gotcha

you know when I pulled the hose off the fuel filter it was definitely pressurized. No telling how much. It seems like when the pump started acting up was after being put under a big load. Son was coming home from college and 1 particular interstate interchange is BAD. it is a tight loop then a short merge lane. He hammered hard in 1st and 2nd gear to get back up to speed and merge. If the pump was close to crapping out this definitely would have been a test for it. Going to drive again today after work. My son is 4.5 hrs away at school so the drive to take the car back to him will be a good final test, lol. Hope all goes well.

It could be the fuel pump controller which actually modulates the voltage to the pump. Those have been known to go bad.

I have read that and located it in the car, easy, just in case. If it keeps acting up that will be my next move. Like I mentioned, my son said he could hear the pump making noises that weren't normal so that tells me either the pump or the controller. In my MR2 the air flow meter told the pump to come on and those things were as reliable as the tides.

So took it out for a 2nd drive and pushed it hard in the first 3 gears with no issues. Took the car back to my son at college, aprox 300 miles. No issues. He has had the car 2 days so far with no issues. Think it really was the pump itself. If something changes I'll post back.

That's odd, the OEM pumps are usually super stout. Oh well, great to hear it wasn't something more serious!

well, spoke to soon. Son called wife and said problem is back. Haven't talked to him yet but wife said he said revs are all over the place

Son just said that it's idling at 2000

It sounds like an electrical issue, you may have moved some stuff around to knock some corrosion loose or make a contact in a broken wire. These problems are very hard to diagnose over the internet. I return to my previous suggestion, use the FSM troubleshooting section. High sustained revs is usually caused by a vacuum leak and so are hunting revs. With the car being so old it could be as simple as a vacuum line somewhere being cracked or as complicated as a leaking diaphragm in the fuel regulator or brake booster. Could also be electrical. Try the troubleshooting section, its helped me so much throughout my work on Z32s.

will try. problem is cars is 280 miles away with son at school. if it was vacuum, why would it run fine for hrs then 2 days later act up?

son just sent me a pic of the pump control module. The ones Ive seen on ebay all have a #4 on them. His has what appears to be an 11. Most of the other numbers match but not all. Does it matter or are they just different because of production years.

scottgas wrote: ↑

Tue Mar 09, 2021 8:29 am

will try. problem is cars is 280 miles away with son at school. if it was vacuum, why would it run fine for hrs then 2 days later act up?

Stuff warms up and expands, electrical component frees up from a bump in the road, bad hose connection of loose hose works its way loose. . .

Like I said, its really hard to do more than throw stuff at the wall when doing this through a keyboard.

scottgas wrote: ↑

Tue Mar 09, 2021 12:25 pm

son just sent me a pic of the pump control module. The ones Ive seen on ebay all have a #4 on them. His has what appears to be an 11. Most of the other numbers match but not all. Does it matter or are they just different because of production years.

Never really paid attention to the big numbers. Also AFAIK there are only 2 versions, the NA 2 speed, and TT 3 speed. They can both be used with a NA ECU but only TT FPCU should be used with a TT ECU and requires the 3 speed wiring. Basically
https://conceptzperformance.com/wiki/in ... ntrol_Unit

son just checked battery cables and they are tight. We havent really had to work on the car so nothing would have gotten disturbed by us. He checked the brake booster vacuum hose and said it looked and felt fine and looked around at the other vacuum hoses and said they seem fine.

you'd think if the control module was bad the 4.5 hr trip back to his school would ha e heated it up enough to fail, IF it is indeed bad. Electronics do funny things though when they are starting to go out though so... Gonna try a pump controller next. and see

bypass it to test and see if the problem returns, just make sure you are driving it pretty hard when you have it bypassed as per the link I posted.

just looked at the bypass link. easy enough. not sure Momma will want son fiddling with jumping wiring. I just ordered a unit from Z1. once I get it and get up to his school I'll bypass to test before opening package.

Throw some new injectors in it.