My 300 ZX has been having some fuel issues lately which was causing the engine to run horribly. Sometimes my car would have a very rough time starting which made me have to increase the throttle while starting. It also had a noticeable shake while idling and some hesitation during acceleration. I opened my hood to check things out and after short inspection I noticed there was fuel spewing everywhere right underneath the fuel pressure regulator. The shorter of the two fuel lines that connect to the FPR dry rotted over time and was leaking fuel at a massive rate. I tightened up the clamps some more and the car ran slightly better, but not like it used to a week ago.
Last winter, I tightened up the fuel clamps, but this particular fuel line clamp came loose again because the fuel line deteriorated over time and it was leaking near the clamp on the end. I’m guessing a faulty fuel pressure regulator also had something to do with the leaking fuel line.
I decided to replace all of the spark plugs, OEM fuel dampener, OEM pressure regulator, and as many fuel lines as I could reach (there was only one under the plenum intake manifold I didn’t get). I got spark plugs just in case the fuel pressure regulator messed them up. I replaced my fuel filter when I did my timing belt maintenance not too long ago, so I ignored the fuel filter.
I also replaced my stock “accordion style” intake hoses with some new chrome hard intake pipes with red couplers from Z1 Motorsports because the inner rubber on my driver side intake hose started to fold inward where it connects to the throttle body — potentially creating an intake air leak. The rubber on the accordion intake hose kept getting worse every time I would take them off and clean the throttle bodies, so I just decided to replace the pipes. Installation was relatively easy. I sprayed some WD40 on a shop towel and rubbed it on the inner part of the couplers and they slid right on with ease. WD40 makes the job 10x easier, as usual. In comparison to the stock intake piping, the Z1 intake pipes look way better IMO. The pipes were fairly priced in comparison to some other intake pipes and of course, the parts shipping is always insanely fast from Z1.
After replacing, the car is starting right up like normal, I’ve noticed an improvement in acceleration, and the idle has also improved. Next up on the replacement list is the idle air control valve unit. I’ve already replaced the hoses for the IACV when I did my timing belt maintenance because they were trashed and no good.