After getting all the little things worked out on my z.The fuel pump was priming for the the 5 sec period just yesterday and today it just keeps running with the key in the on position.

I checked and cleaned all connectors ect.I wired in my own fuel pump relay when i did my turbo swap(four years ago) and thought that was problem,Put a new relay in and no change.The car will start,but won't idle.It revs just fine.I have to keep my foot on the gas or the engine will stall.Keep in mind this just happend today.The car was running strong yesterday with no issues.Any ideas on what the problem maybe?

 

Keep in mind that I bypassed the fuel pump controller on my turbo Z which regulates between 14v and 9v for idle. My car still idles smooth and the fuel pump runs all the time with the engine on. The lower voltage was to decrease amperage draw and noise, not to aid in running at idle. The system still primes for 5 seconds before startup, but once the engine is started, the fuel pump runs continuously.

The system should keep the proper fuel pressure regardless. I would look first to a faulty fuel pressure regulator on the fuel rail.

 

Thanks for the advice.The one thing i forgot to mention was i changed my boost gauge connection and tied into the fuel pressure regulator.That maybe the problem.I'll post back the results.

 

Just got back from working on the z.Re-locating the boost gauge hose didn't change anything.The fuel pressure regulator seemed ok.I'm starting to think i may need a new pump.Would the fuel pump still operate even if was faulty?It seems louder then usual.

 

I take back stating that the fpr is ok.I forgot i do have an extra one to install.I'll install the extra one and see what happens.

 

I have the same problem after I did the head gasket a couple years ago. It primed for 5 seconds before the head gasket and just ran and ran after. When you figure it out let me know.

 

Well, I put the other fpr on today and still no change.If anyone has had this problem in the past,Please let me know.I don't want to go out and buy a new fuel pump if i don't have to.

 

I know that pulling the plug out of the back of the alternator will cause the fuel pump to stay on at all times the ign is on. That's a standard test for the fuel system on these.

 

Wow i pulled the alternator plug out and back in and the fuel pump is priming for the 5 second period and turns off.The engine still won't idle.I have to keep my foot on the gas.

I did take it for a short drive and had full power.I don't know if the pump is bad or not.I was thinking maybe the inlet screen became clogged up all of a sudden or the fuel filter needs replaced.I'll probably get a new one anyway.

 

Cleaned the inlet screen today and the car runs just fine now.

 

by the pump? ..or in the tank? Where iz it?

 

Yeah would like to know as well, mine seems unusually loud.. Almost as bad as my Sisters Chevy

 

loud is normal for a 280zx

 

At the risk of sounding stupid, i take it the 280zx runs an out-tank pump similar to old Chevys (90s), hence the loud noise. Or am i mistaken and it is an in-tank pump?

 

Indeed. Inline (external) pump.

 

I had the same problem with the fuel pump running. It turn out to be a bad (shorted) alternator. The alternator died a few days later. A new alternator (remanufactured not rebuilt) took care of all problems. I don't know if this will help you but it worked for me.