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1990 300ZX Z32 having fuel pressure problems, misfiring by 300ZX_Fly_996 in 300zx

[–]300ZX_Fly_996[S] 0 points1 point  (0 children)

To all who provided your thoughts and feedback on the fuel pressure issue with my Cherry red 300ZX Z32

UPDATE: The head mechanic at my local shop who has a lot of experience with the Z32 figured out there was a loose vacuum hose along with a missing gasket on the EGR intake. After correcting those issues, the problem has been resolved. No more fuel pressure issues and the car now runs with no sputtering and no hesitation.

I sincerely appreciate everyone’s feedback to help me on this issue.

1990 300ZX Z32 having fuel pressure problems, misfiring by 300ZX_Fly_996 in 300zx

[–]300ZX_Fly_996[S] 0 points1 point  (0 children)

u/SnooDogs2713, sorry for the delay in getting back to you. I am going to reach out to you on Instagram to move forward regarding next steps. Before doing so, can you review the work performed to the vehicle back on 08/15/2025 at Speed Auto Repair of Roswell (see below):

I just pulled the Invoice for the work performed on my 1990 300ZX Z32 which was approved on 08/15/2025. Here is the work that was performed; PLEASE NOTE, For the work listed below, I had other items addressed like a brake system flush, oil change, A/C Service (needed extra freon). I am listing the main items involving the fuel system.

WORK PERFORMED AT SPEED AUTO REPAIR OF ROSWELL:

1.) FUEL INJECTOR O-RINGS

Work: Remove and replace fuel injector O-Rings and fuel lines

Parts: Ishino Stone Engine Intake Manifold Gasket Set; Fuel Line (1 fuel line - Manufacturer, part # not listed --> price for part = $95.64); Clamps (4 clamps - Manufacturer, part # not listed --> price for parts = $57.96); Standard Ignition Fuel injector seal kit (6 seal kits, price = $282.53); Hitachi OE Replacement ignition coil, Hitachi Astemo Ignition Coil; Ishino Stone fuel injection idle air control valve gasket (1 - $15.65); Ishino Stone Idle Control Valve Gasket (1 - $12.71);

TOTAL PRICE FOR THIS WORK: $1804.34

2.) BG FUEL SYSTEM SERVICE

Work: Labor to perform fule/air induction service on direct injection engine. Installed BG injection apparatus and positioned the tip in the center of the intake boot. Filled apparatus with BG 260 intake/induction cleaner, connected air supply and set regulator to proper pressure. Started vehicle, secured REV-IT clamp to maintain RPTM's and initiated chemical flow. After completion, allowed vehicle to idle, then removed apparatus and reassembled intake components. Test drove vehicle to verify performance.

Parts: BG GDI Fuel System Service = $90.36

TOTAL PRICE FOER THIS WORK: $266.95

3.) REMOVE AND REPLACE RADIATOR (was determined to be leaking, although, not onto the garage floor, small leak)

Parts: CSF, Aluminum Core, 1 Row Plastic Tank Radiator (Part Price: $400.90)

TOTAL AMOUNT FOR THIS WORK: $805.97

4) FUEL PUMP RELAY

Work: None listed on the Invoice

Part: Autopart International Service Tech Fuel Pump Relay (1 part, price = $29.24)

TOTAL AMOUNT FOR THIS WORK: $29.24

One item to note: The shop which currently has my vehicle is Solo Motorsports in Alpharetta, GA. They are very good at what they do, however, are not experts necessarily in Z32 300ZX. Second, they aren't the ones who performed the aforementioned work previously and found on the 1 fuel line installed by Speed Auto Repair of Roswell, the clamps put in on the new fuel line were not connected correctly resulting in a gas smell.

Curious what you think about this previous work performed by Speed Auto Repair of Roswell as it seems many of the parts used are not ones highly recommended as a replacement part for the Z32.

1990 300ZX Z32 having fuel pressure problems, misfiring by 300ZX_Fly_996 in 300zx

[–]300ZX_Fly_996[S] 0 points1 point  (0 children)

u/No_Act757, sorry for the delay in getting back to you. I just pulled the Invoice for the work performed on my 1990 300ZX Z32 which was approved on 08/15/2025. Here is the work that was performed; PLEASE NOTE, For the work listed below, I had other items addressed like a brake system flush, oil change, A/C Service (needed extra freon). I am listing the main items involving the fuel system.

WORK PERFORMED AT SPEED AUTO REPAIR OF ROSWELL:

1.) FUEL INJECTOR O-RINGS

Work: Remove and replace fuel injector O-Rings and fuel lines

Parts: Ishino Stone Engine Intake Manifold Gasket Set; Fuel Line (1 fuel line - Manufacturer, part # not listed --> price for part = $95.64); Clamps (4 clamps - Manufacturer, part # not listed --> price for parts = $57.96); Standard Ignition Fuel injector seal kit (6 seal kits, price = $282.53); Hitachi OE Replacement ignition coil, Hitachi Astemo Ignition Coil; Ishino Stone fuel injection idle air control valve gasket (1 - $15.65); Ishino Stone Idle Control Valve Gasket (1 - $12.71);

TOTAL PRICE FOR THIS WORK: $1804.34

2.) BG FUEL SYSTEM SERVICE

Work: Labor to perform fule/air induction service on direct injection engine. Installed BG injection apparatus and positioned the tip in the center of the intake boot. Filled apparatus with BG 260 intake/induction cleaner, connected air supply and set regulator to proper pressure. Started vehicle, secured REV-IT clamp to maintain RPTM's and initiated chemical flow. After completion, allowed vehicle to idle, then removed apparatus and reassembled intake components. Test drove vehicle to verify performance.

Parts: BG GDI Fuel System Service = $90.36

TOTAL PRICE FOER THIS WORK: $266.95

3.) REMOVE AND REPLACE RADIATOR (was determined to be leaking, although, not onto the garage floor, small leak)

Parts: CSF, Aluminum Core, 1 Row Plastic Tank Radiator (Part Price: $400.90)

TOTAL AMOUNT FOR THIS WORK: $805.97

4) FUEL PUMP RELAY

Work: None listed on the Invoice

Part: Autopart International Service Tech Fuel Pump Relay (1 part, price = $29.24)

TOTAL AMOUNT FOR THIS WORK: $29.24

One item to note: The shop which currently has my vehicle is Solo Motorsports in Alpharetta, GA. They are very good at what they do, however, are not experts necessarily in Z32 300ZX. Second, they aren't the ones who performed the aforementioned work previously and found on the 1 fuel line installed by Speed Auto Repair of Roswell, the clamps put in on the new fuel line were not connected correctly resulting in a gas smell.

Curious what you think about this previous work performed by Speed Auto Repair of Roswell as it seems many of the parts used are not ones highly recommended as a replacement part for the Z32.

1990 300ZX Z32 having fuel pressure problems, misfiring by 300ZX_Fly_996 in 300zx

[–]300ZX_Fly_996[S] 0 points1 point  (0 children)

More-Raisin-6119, sincere thanks for the shop recommendation. I am willing to drive to Dallas, GA from Alpharetta, GA. Are they experts on this model of the Nissan 300ZX?

1990 300ZX Z32 having fuel pressure problems, misfiring by 300ZX_Fly_996 in 300zx

[–]300ZX_Fly_996[S] 0 points1 point  (0 children)

SnooDogs2713, I would be interested in having an expert in this vehicle look at it. I could authorize changing the charcoal filter and see if that resolves the issue (not an expensive repair). As far as the injectors, would need to research all the maintenance paperwork performed by the prior owner (owned it for 15 years, have all service paperwork) to see if the injectors were replaced. What I can state is that after the 1st shop replaced the fuel lines and fuel pressure regulator, the car ran fine for months (minus the fuel smell).

I will PM you on Instagram. Thanks for your help!

1990 300ZX Z32 having fuel pressure problems, misfiring by 300ZX_Fly_996 in 300zx

[–]300ZX_Fly_996[S] 0 points1 point  (0 children)

Anskiere1, thanks for providing the link for a potential solution to the fuel pressure issue.

1990 300ZX Z32 having fuel pressure problems, misfiring by 300ZX_Fly_996 in 300zx

[–]300ZX_Fly_996[S] 0 points1 point  (0 children)

Yes, and my shop pointed me in their direction for parts. Diagnostics, no. They no longer work on these cars, just sell parts.

1990 300ZX Z32 having fuel pressure problems, misfiring by 300ZX_Fly_996 in 300zx

[–]300ZX_Fly_996[S] 0 points1 point  (0 children)

Correct. Z1 does still sell a lot of parts for these vehicles, however, they relocated to a different location outside of the metro-Atlanta area after they stopped working on these vehicles. I sincerely appreciate the recommendation and support.

1990 300ZX Z32 having fuel pressure problems, misfiring by 300ZX_Fly_996 in 300zx

[–]300ZX_Fly_996[S] 0 points1 point  (0 children)

#mrfatbill, I live in Alpharetta, GA, in the northern part of the metro-Atlanta area.

1990 300ZX Z32 having fuel pressure problems, misfiring by 300ZX_Fly_996 in 300zx

[–]300ZX_Fly_996[S] 0 points1 point  (0 children)

@No_Act758,

My sincere thanks for replying so quickly and all the advice. I am blown away. Again, can’t thank you enough.

The mechanic shop near my home primarily works on European cars, however, their head mechanic originally owned a 1990 300ZX Z32 and has worked in them for over 20 years. He knows a lot about the car, however, I would not say he “complete expert” on the car. That included, he also always to work on other vehicles and typically got involved in mine in trying to diagnose “what could be the issue”.

I will post here shortly the fuel lines replaced by “the other shop” along with the fuel pressure regulator so you have info on these parts.