ThatDude114

Hey guys, I have a 1984 300zx Turbo GLL that sat for awhile. I have a no start issue right now. I have air, and I have spark, and I have fuel to the fuel rail. I'm not sure of the fuel pressure yet but it seemed like it was flowing plenty fast. The next step is checking for injector pulse correct? Also, my Fuel Pressure Regulator is making a hissing noise like it has an air leak, that means it's probably bad right? Could this cause a no start issue? Next, whenever I turn the key on the fuel pump turns on and stays on indefinitely, is it trying to make up for lost pressure because of the FPR or could there be a different cause? Finally, my fuel gauge on my digital dash is blank, the only thing that works is the orange light directly above it, I resoldered the pins on my power supply so that shouldn't be an issue, which means it's something with the dash right? I've only heard of 2 other cases where this happened, one of the guys said he just took the dash to a dealer and they resoldered something in his dash for $50, anybody have a clue on what they resoldered? Thanks for taking the time to read this guys.

rogerz

your are probably hearing the vacuum pump run when you turn the key NOT the fuel pump. saying your fuel system is working because gas comes out is like hoping for a lottery ticket to win that you never bought. Put a gage in there fella! Very unlikely the hiss is coming from the fpr UNLESS of course your fuel pressure is like 1psi. Fuel sender likely bad or wires going to it are compromised. Without solid data on fuel pressure to the injector ring you are just howling at the moon

ThatDude114

I'm 99% sure that it's the fuel pump, I can put a screwdriver to the gas tank and hear it running in there, and I can feel a slight vibration on the tank whenever I hear the sound. I'm still looking for my fuel pressure gauge that I bought but I might just have to buy another one. I'm also 99% sure that the hiss is coming from the FPR, it goes away whenever I pull the fuel pump fuse out, and I believe that the sound is the fuel running through the FPR. If I let the fuel pump run for like 20 minutes, I'm able to start it for a second off it's own gas. Is there a way to see if my injectors are cycling? And is there a way to tell my injectors are stuck open? I was talking to a mechanic at my local Nissan dealership and he thought that maybe my injectors were stuck open and that my fuel pump was just dumping fuel into my cylinders and flooding it out, but this doesn't sound right to me, does that make sense to any of you guys? Also, when you were talking about the fuel sending unit, it's not that the gauge is off or anything, it's not lighting up at all (Digital Dash), shouldn't it still light up if there's something wrong with the fuel sending unit? I appreciate all the help man

Update: So I wasn't able to find my actual fuel pressure gauge so I took an old air gauge and made one. I hooked up the hose to the fuel filter and the pressure was something around 55 PSI coming out. So that means that my fuel pump is good right? Also, when I turned the car on when I had the gauge on, the fuel pump did shut off after 3 seconds. So that means the problem lies between my fuel filter and the fuel rail/injectors. I've heard of the Z31 fuel rail leak, however I don't smell gas and I don't see any fuel leaking from the injectors. So where is all the fuel going? Should I test the fuel pressure at a different location? Does the Z31 fuel rail have a schrader valve for checking fuel pressure?

rogerz

55 is way too high. your FPR is likely shot. lay down with head under the car by the right wheel and you will see the vacuum pump. If the fuel pump is making more racket than the vac pump it is shot so I doubt that is the case if you got 55 psi. You can buy an oil pressure gage at any auto store for under $10 bucks. YOU NEED TO KNOW YOUR FUEL PRESSURE. pressure gage could care less what fluid it measures so just get one!!! no schrader valve. the only relevant place to check fuel pressure is between the filter and the injector ring. If you don't like my advice ignore it and throw a bunch of money at the car changing parts.

ThatDude114

Oh I don't have the money to just throw funds at a car without troubleshooting, so I really appreciate the advice. After doing so much troubleshooting on my Jeep I actually find it kinda fun. I know you know your stuff, so I'm more than willing to listen. The 55 PSI was taken between the fuel filter and where the hose goes onto the fuel rail, is this where you're meaning I need to take the pressure reading at? Shouldn't the fuel pressure be higher because the reading was taken before the FPR? Is it possible that the FPR is so bad that it's causing a no start? Do aftermarket FPR's okay? Or buy factory only?

Does anyone know how to depin the climate control connector? Someone pulled one of the wires out of mine and then tried to depin it and just made a mess. Or does anyone have a climate control pigtail that they'd be willing to sell?

rogerz

you are getting the pressure at the correct location. you however don't understand your fuel system. Either READ the manual or download the fuel injection bible (ALTHO meant for earlier cars the principals are valid. The fpr sends excess fuel back to the tank to maintain an even pressure on the ring as the pump delivers more fuel than needed for the engine. Fairly common engineering solution as to how to keep steady pressure in a system. SO LESSON ONE. either the fpr is shot or the fuel return to the tank is blocked. Get that working you probably have solved your problem. SECOND convince me you looked at the vac pump and still think you hear the fuel pump run. on my 86T the pump is a low murmur barely audible unless really listening and the vac pump is disconnected. pull the pump fuse and see if you still get noise.

don't worry about the connector just solder a jumper over the connector to give the proper wires continuity. it isn't like you will be disconnecting it on a daily basis. or add an inline one wire connector if it makes you feel better. just remember any connector is just another point of failure added into an already antiquated and complex system

here is some unsolicited advice but if you like your z31 you will like it better after this:
Get your battery load tested. Be sure you have clean, tight corrosion free terminals on both ends of your battery cables. Be sure the ground (negative) cable goes to a bolt into the frame before going to the starter. grounding through the starter is not a reliable connection. Z's don't like low voltage. causes the electronics to act funny. it is possible to have enough amps to crank but not enough voltage to run the electronics. If you have one size fit all cheapo clamp on terminals they are a problem waiting to happen. Usually on a rainy night around Oh Dark Thirty.

Clean the connectors for the maf or afm, ecu and tps. Deoxit by CAIG is probably the best connector cleaner on the market. spray with CorrosionX after cleaning and before putting together this will help prevent any further corrosion.

Replace outer tie rod ends, and ball joints. replace the bushings with poly (don't forget to lube them as directed unless you like squeaky things). New shocks. Get new boots for power steering. all those things will make you think you are driving a different car. doing them piece meal is a waste you won't see a great improvement until you do the complete job. You need to get the car realigned after messing with the front. Have your tires in good shape and rebalance. Rear bushings nice too but more work and you won't notice as great an improvement. Rear shocks also because if the fronts are gone so are the rears. if car squats when you jump on the gas the rears are gone. If you have the electro adjustable shocks they are DEFINITELY GONE.

If you are doing a turbo car shocks (electro adjust I think may be only on the turbos) then you need the adapter plates to fit modern shocks to the car. Easiest way is find an n/a at the junkyard and take the mounting plates. They may be available thru NAPA (listed) but I had the n/a plates.