Need Help car will not start

[tgsracing]

I am new to Nissan, I bought a Sand Rail with a VG30DET motor in it and started and ran just fine when I got it. The transaxle needed to be fixed so I pulled the motor. When I put it back in the car cranks but will not start, it has the factory wire harness tied into a LinkPlus V.14 ECU and so everything simply unplugged and plugged back in. The only thing I did while the motor was out was change the spark plugs. I have done my best to research these forums and came up with a few checks but so far no success. I took the CAS off and spun it and the injectors are firing, I did perform the ohm test on the PTU and it passed however as a last ditch I did buy and new one and again no success. I pulled a plug and checked for spark and definitely now spark, I check continuity to ground on the black wires going to the coil and PTU and we are good there. I put the old plugs back in the side that is easy to get to and it kicked over, so I went ahead and pulled the intake and changed the plugs on the other side and no luck there. I am not sure of how to check to see if the computer is working properly nothing happened to make me think that it would not work as the fuel pump and fan see to work as they should, even if it lost its mapping I would think that it would still start but not run very well. How can I check the coil pack to make sure they are getting the proper signal, ohm voltage test? If they do not check well where should I go next? I am pretty lost at this point any other checks/test would be helpful and will be happy to supply any other information.

thanks in advance,

Dan

[Ace2cool]

It may very well be a fried computer. I would see if you could get your hangs on a stock unit to troubleshoot with. Did you say that it is or is not getting spark? Have you verified that there is a good fuel supply pressure?

[nissanfreak12]

Im with Aaron on this, you checked everything else but the fuel. When you pulled the plugs were they wet at least? Possible the lines were reversed when you put the engine back in.

[tgsracing]

I guess it could be possible that the lines were reversed, I would say it has an upper and lower fuel line going to the regulator, the upper line comes from the pump and the lower line is the return to the tank does this sound correct? I know the fuel pump kicks on when you turn the ignition on and when you turn the CAS manually you can hear the injectors click and the fuel pump keep pressure. Do you guys know if there is a way to check the computer to tell if it is bad besides getting another one? Can part of the computer be bad and not the other part, in that I mean the fan and fuel pump work and they run through the computer and if I am not mistaken on this particular one the fuel pump and ignition are on the same circuit.

Thanks,

Dan

[nissanfreak12]

The line to the back of the engine is the return line, the line to the front of the engine should have a filter and that one comes from the pump on a 90-96 motor, you said you have a VG30DET, that is from an older 300zx, 84?-89. That I am not sure about the fuel lines, Does your engine have dual Throttle bodies or just one? One turbo or two?

[tgsracing]

My motor has dual throttle bodies and a single turbo. I only have two fuel lines, one coming from the pump to the regulator and one coming from the regulator going to the tank, the regulator is at the front of the motor.

[NolimitZ32]

[nissanfreak12]

Just try and swap the lines and see what happens, very possible it is wrong. Since this is on a sandrail, who knows how it got set up. Keep us posted.

[tgsracing]

The fuel system is definately hooked up properly the line from the pump goes to the regulator and I was mistaken on the return line as it comes from up from the fuel rail then back to the tank. I never unhooked the vacuum lines or the lines from the regulator to the fuel rail.

[Ace2cool]

you said you have a VG30DET, that is from an older 300zx, 84?-89.

Close, but big difference: VG30ET is the '80s model. SOHC, not DOHC. His is a Single turbo converted VG30DETT, sounds like.

So we've
Checked spark, (I think? Was your "now getting spark" supposed to read "not?")
Checked CAS,
Ohmed PTU,
Heard injectors clicking when rotating CAS,
Fuel pump primes, but haven't checked pressure.

Does your ECU support diagnostic capabilities? I'd try pulling codes and hope for anything but a 55, lol.

[tgsracing]

The more i am into this project the more I think there is something wrong with the computer, unfortunately, it is a stand alone Link ECU that I do not have the serial link pieces to hook up to a computer to get any information. I wish I knew of a way to check so voltage or ohm outputs to see if it is sending a signal out.

On the motor thing, I read on Wikipedia (I know not the best source) but that 4 cam, dual throttle bodies, and single turbo motors (VG30DET) were in-fact produced but offered in Japan or Australian vehicles only like the Nissan Leopard or Nissan Cima. I could be very wrong but that is what I had found when trying to learn things about this project.

[NolimitZ32]

Look in the FSM, if you are running all Nissan sensors, all the voltages and other parameters are in there, EF/EC section

[Ace2cool]

Good call, they were in the Leopard and Gloria for sure. Pretty sure they were in the Y32 Cedric as well for the Japanese market. I don't imagine the engine would be changed very much between the two, but here's a link to
the FSM for the 1990 Infiniti M30:

http://www.nicoclub.com/FSM/M/1990_M30/M30_1990_FSM.pdf

The M30 is the same thing as the Cima, only with the VG30DE instead of the VG30DET. Like I said, the blocks are basically the same, I'm just not sure if the M30/Cima have the same quirks as the Z32. Maybe pop in over in the Cima/M30 forum and ask about this. If you've got any more questions for us though, feel free to ask!

[tgsracing]

Well great news problem solved, bad news I am kind of an idiot. Nissanfreak12 had the answer in the swaped fuel lines, I started really thinking fuel after you guys brought that up as a reason. Being used to carburated engines I assumed that the fuel line went to the regulator first well that is clearly not the case for fuel injected engines. I will chalk it up to learning experiences, I started looking at some pictures I had taken prior to tearing it apart and then I noticed the fuel line differences. At any rate I appreciate all of the feedback I received and will definately be back for help in the future.

Thanks,
Dan

[marty1mc]

It doesn't make sense at first, but if you think about it, it does. Putting the regulator after the fuel rail causes consistent pressure on the fuel rail and allows the pressure to build faster.