ahaav

Hi everyone! New member.
I have a '91 300zx Twin Turbo with about 67,000 miles on it.

Recently, I've been having lots of trouble starting my car. Basically, I have to step on the throttle several times before it even begins to fire, then I have to rev it up a lot once I finally get it to start to prevent it from dying. After all this, the car runs fine. Revs are even and pulls are strong. After I park and shut it off, I am forced to go through the same hassle of starting it.

Requiring the throttle in order to start points to a fuel system problem, correct? I have aftermarket Nismo 555cc fuel injectors, the rest of the fuel system should still be stock though. I was going to maybe test fuel pressure, then go and replace the regulator/pump/damper/lines accordingly. Sometimes, I'm able to smell fuel from inside the car. But this is only in some situations.

Any and all help is greatly appreciated. Thanks!

BlueKitsune

Its hard to start hot or cold?

If its hard to start only when cold I'd actually point a finger at the Idle Air Controller myself.

ahaav

It is hard to start both hot and cold.

BlueKitsune

I would do like you said and check your fuel pressure. make sure it doesnt drop off when you turn the Z off.

I'd also check for any vacuum leaks as they can do the same thing. And if all that is good I'd start checking the TPS and the CAS And maybe the PTU if you have the first generation of them. I don't remember when they switched them over...

ahaav

I'm going to go ahead and replace the fuel system. About to buy this kit: 300ZX Fuel Pressure Regulator, Damper, & Lines

It also says that I should replace the fuel filter every 60,000 miles, and I know that hasn't been done yet. So I'm going with this fuel filter: Nissan OEM 300ZX Fuel Filter - Nissan performance parts

Any thoughts or comments? I know that the next step after doing all this should be brushing up on all the connectors and making sure they're clean and stuff. Should I replace the fuel pump at this time?

ahaav

Purchased new fuel pressure regulator, damper, and lines. Also going to replace the fuel filter while I'm at it. After this is all replaced, I'm hoping it'll be good for another 60k miles or so. I also hope it solves my problem. Should I replace the fuel pump while I'm at it? How long is a fuel pump usually good for?

I suppose after resolving all this, the next step would be checking my wiring and connectors and cleaning them up.

BlueKitsune

If you're already going that far it probably wouldn't hurt maybe go for an upgraded one sense your running larger injectors. But thats just my 2 cents

ahaav

Larger fuel pump? Very well!

Also while reading the install procedure, it says that this would be a good time to delete the PRVR. Since I am going for a cleaner engine bay, I'm looking to do remove that as well. Plus it'll be one less thing that could go wrong.

KSpakes87

While pressing the throttle the only thing you are controlling is the air flow on a EFI vehicle. The computer takes readings from multiple sensors to decide how much fuel to deliver.

By pressing the throttle while trying to start you are first causing the TPS to take a higher reading then once the engine starts to pull air in it is taking a measurement from the MAS.

You are never controlling the flow of fuel. Only the flow of air. The ECU determines the fuel input. Hence the name Electronic Fuel Injection (EFI).

I would first test the TPS and adjust if it needs to be and then check for vacuum leaks. Then check your MAS.

ahaav

Alrighty. Tomorrow I am going to be checking the car out. The part that throws me off is that it runs absolutely fine after I get it started. Wouldn't a TPS or MAS issue show other signs of being present? Such as erratic idle? I'll let you guys know what I find under the hood tomorrow.

ahaav

Bad news. It's about 25 degrees Fahrenheit here in Connecticut, and some components have frozen on my car. My keyless entry wasn't working and I couldn't open the driver side door. Finally was able to open passenger side door with the key, and crawled into the driver seat.

When I tried starting the car, all I got was a bunch of quick clicking noises. Must be a dead battery. Have no idea how or why it happened, but I now have another setback. FUUUUUUUUUU.

KSpakes87

Well good news for you, all your problems could be solved by replacing the battery. A battery is rated by Cold Cranking Amps (CCA). This is measured by Amps while below 32 degrees Fahrenheit.

When a battery starts going bad it can cause the car to struggle to start while above 32 degrees. When temperature drops below 32 degrees it puts even more strain on the battery.

If you are getting a bunch of clicking noises, this means they starter solenoid is good, but the battery has a dead cell or a cell (or multiple cells) going bad.

First thing you need to do is have your battery tested. Any parts store can do this. They will charge it and then test it. When weather turns cold battery problems become more apparent.

ahaav

Found the main culprit! And hopefully the only one....

She starts perfectly fine, depending on what angle this corroded cable is at. It seems to be connected to a fuse box for accessory electronics on the car. If this cable is out of place, absolutely no electronics on the car work. If it is at the right angle, the car seems to start perfectly. Does anyone know where I can get this cable at? Is it universal and does it plug right into the fuse box?

Oh and btw, in the 2nd picture with the green circle around the thinner wire is connected to an aftermarket boost gauge.

ahaav

Can't find info on this red wire anywhere. Not sure if this is the one that goes to the alternator, or if this goes to the fusible link box. Anybody got anything?

ahaav

Here's my hit and miss cold start.

300zxTT - Cold Start Trouble - YouTube

KSpakes87

That almost acts like a bad IACV the way it's cranking fast, but not starting. Could be wrong on that. A possibility could be a weak fuel pump. Check fuel pressure and make sure it's right. Would definitely want to be testing while it's in its no start situation.

ahaav

Alrighty sounds the good. So anybody know where that wire goes though? I think it goes to the starter, but won't be able to find out till I lift it. I need to replace that wire altogether, I believe I just need to cut my own gauge wire and fit ends on it?

KSpakes87

I was looking on mine earlier and from the top it looks like the bigger wire goes to the starter and the smaller goes to a fuse box and then alternator.

ahaav

Alrighty. Hopefully get her up on the lift tomorrow. Going to find out how that wire connects to the starter, then replace it accordingly. After that, going to see how well it starts and hopefully that'll be the solution to my problem!

ahaav

She didn't start at all today. T_T

Just the starter solenoid clicking, and some very weak cranks. I don't have access to the shop till Wednesday. Still possibility of sensor failure?

KSpakes87

Have you had the battery tested yet?

ahaav

Nope. Getting it all done tomorrow I hope. Probably going to jump start her and get her down to the shop on base. If that doesn't work, I'll have to pull the battery then and there and get it tested. Either way, I'm probably looking at getting a new battery. I have a feeling that is one of the culprits.

Got any tips of getting to the starter and pulling out the wiring once I get it on a lift? Shouldn't be too hard I hope.

Also, my aftermarket voltmeter bounces slightly and stays right at 8V, which is the lowest reading on there lol....

KSpakes87

The starter is located on the passenger side of the transmission. Should just be able to disconnect the wire from there and the battery. I can't remember if it's held up by any clips going between them.

As for the volt gauge showing 8V, assuming the gauge is correct then it sounds like a weak alternator. The gauge is measuring the alternator output. That could be the source of the battery issue also. When an alternator gets weak it undercharges the system. Thus causing the system to pull power from the battery and eventually causing it to fail due to being overworked. The battery is just to power the starter and accessories. When the car is running you could disconnect the battery and it will stay running with a good alternator. Most alternators put out about 14V-16V.

I would start by having both battery and alternator tested. Your local parts store will usually do this for free. If you can get the car down there they can do this with them still on the car.

ahaav

Issue solved. Battery was done for lol. Leaking acid everywhere, etc. Need to get alternator tested, but bought Duralast Gold and everything is running good now.

I want to relocate the battery to the trunk. The cowl is broken and held on by the hood now. The harness is corroded and everything is just a crumbling mess.

KSpakes87

Great! I'm glad you got it solved.

Most cowl pieces I see are always dry rotted. When I bought my Z it didn't even have them. I have managed to fine a good drivers side piece. Still need the passenger side. They are expensive new.

What is your Volt Gauge reading now?