HELP! Car died, fuel related!

[USAFguy22]

I was driving back from lunch today and my car suddenly died about 1/2 mile from work. It's a '91 and CTSC'd about 3k miles ago. I've been driving it all week without issue and did a quick diagnostic. I have the SoS fuel pressure gauge installed on my fuel filter, when I turn the key to the second click pressure builds up to 60psi and immediately starts to drop down to zero. I tried this a few times and it's repeatable, as if it gets power for a second or two but then stops.

Any ideas? I haven't had a chance to check the #5 fuse in the footwell since I'm sitting at work now. And I had a quick look at the main relay and all looked ok (from what i can see)

 

[arista5]

have you tried a new relay? relays break inside not outside

 

[NSXcitement]

So it will start, but immediately dies?

 

[USAFguy22]

The CTSC has a fuel pump regulator unit that replaces the main relay (I think?), so could it be a bad unit?

- - - Updated - - -

So it will start, but immediately dies?

it will ignite a couple revolutions if I crank it immediately but if I wait as if I were priming the fuel pump then the pressure is already gone and I get nothing.

 

[NSXcitement]

It sounds similar to a problem I had with my 968. It had a sensor on the flywheel that produced a crank position signal which kept the fuel pump relay energized. The idea being that if you're in an accident and the engine stops, it automatically shuts off the fuel. It could be anything in that circuitry that is open or intermittent; the sensor, connectors, wiring, the relay...

 

[USAFguy22]

Once I get it home I'll check the wiring with a multimeter and see if I can track the problem. I'll keep this thread updated.

 

[USAFguy22]

So I've narrowed down the problem, and with a multimeter my friend was able to find the voltage booster is faulting and cutting the voltage to the relay for the fuel pump after about 1 second. The signal going into the box is constant 12v and the signal coming out it 12v (1second) to zero, thus causing the fuel pressure spike and instant pressure bleed off. I'm relieved to know it's not my fuel pump dying on me. I talked with Nate at CT and he says he's never seen a new box die so quickly but will be sending me a new one no questions asked, now that's customer service!

Here's a pic of my recovery vehicle, I only needed a tow for about 1.5 miles.

 

[NSXcitement]

Glad you found the cause! :smile: Did you have to tow it in broad daylight?

 

[USAFguy22]

It's was about 5:30pm when we towed it. And I'm pretty sure it's legal here in Kansas (famous last words?). Made it home safe and Nate will be mailing me a new box on Monday

 

[simplife]

Looking at that pic, just thought of a new trick for Nik Wallenda.

 

[USAFguy22]

Well I received a new unit from CT but it's doing the same thing...... The relay keeps cutting out. Not sure what's causing this..... Grrrr

 

[Valhalla]

It could be the fuel pump. I had this same issue. It was a short in the tank but I was running a Walbro wannabe. Didn't know it wasn't the real thing so I got an imitation without my knowledge. All better now.

 

[USAFguy22]

I did some more inspection an discovered the main relay is cutting out. I replaced it maybe a year and a half ago so it's not worn out. I took off the outer case and it looked brand new still, it's the plug on the right side that cuts off after a second. To make sure the relay wasn't the problem I held that side closed and cranked the car but still nothing. So the signal upstream from the main relay is where I'll look next, I just don't know what that will be.

 

[USAFguy22]

So after many hours of tinkering the main relay was fixed (had a bad resistor) and the car is getting fuel. I pulled a spark plug and it's not getting a spark... Every fuse was thoroughly checked and the alarm system is working properly. My next thought is that it could be the ignition control module? Crank/cam position sensor? Any ideas?

 

[MidnightSun]

Any update?

I worry about this kind of problem after I get my CTSC installed.

 

[shawn110975]

never hear of this problem on a stock NSX. what does 400hp really get you???

loss of miles you get from a tank of gas,

10K+ out of pocket for the SC, f

ixable issues from day one,

engine can die at any minute,

cant take it cross country cuz it could break down,

burn thru tires faster,

constant tuning to keep it purring like a kitten,

the USA doesnt have a AutoBuhn to get the needle pinned,

most SC owners ripp it all out when they sell it = extra work.

I still dont see the need for high HP its fast enough and reliable as a stock motor, headers and exhaust is all you need.

not bashing your car in anyway I just dont get why people want to deal with these issues

I can get in my NSX right now and drive from tampa to Alaska and I know for a fact it will make it there, then I could get right back into my NSX and drive back and it will make it there. thats why honda didnt SC the NSX to begin with

 

[Factor X]

Wow, Shawn, that was well said. To each his own, of course, but I agree. If 450 HP was my goal, I would have gotten a Viper (and hated it). I love the NSX for what it *is*.

FX

 

[shawn110975]

Now I wish my car was stock with 400HP that would be awesome if it was stock. and had hondas stamp of approval but.... like you said each person has he own reasons

and who knows this NSX might have been purchased with the SC already installed

if only SC or Turbo which is even worse were more reliable I would get one.

modern cars that are turbo from factory they only warranty the drivetrain for 50,000 miles I wonder why? not reliable is my thought.

now I hope guys dont bash me for not wanting to turbo or SC my NSX but it OK your car is your car, my car is may car.

now get this car fixed and go drive the beast.

 

[chudson1549]

Check your ignitor. I have a fellow ctsc nsx die here for no reason. Check for fuel and went through the whole system with trying main relay, ignition switch. You name it. Never thought about the ignitor. I swapped his out with mine and his car started righted up.

 

[USAFguy22]

I did some research on that part, but wouldn't symptoms of a bad igniter be a cylinder or two dropping? Nothing is firing on mine. So far I've checked:
All fuses good (and circuits checked with multimeter)
Fuel pump relay along with voltage booster replaced
Main replay replaced
Ignition switch is good condition
Fuel pump good (pressure normal)
Signal modifier bypassed to see if that was the problem
Plugs are brand new

Perhaps you could be right, or maybe I have a ground that came loose and the ecu isn't working? Aggggh.......

 

[nsxmm3]

I had the same/similar problem right after I did my SC install. Turned out to be the ground you have to re-do near the rearward ignitor connector. Car would run fine, then suddenly cut-off & not start. I pulled the M6x12 button head allen screw & M6 washer (installed in step #6 of the instructions) out of the intake manifold, cleaned the threads on the screw & threads in the hole. Problem has not returned. Like you, I spent a lot of time troubleshooting before this fixed it. Hope your problem is that simple.

 

[USAFguy22]

I tried unhooking and rebolting the igniter ground wire to no avail. I'm picking up a new igniter tomorrow so I'm crossing my fingers :-/

 

[chudson1549]

Yeah I was thinking the same about just dropping a cylinder. But his just would not fire up until we switched it out. He replaced it been running great ever since.

 

[USAFguy22]

ICM replaced, still not firing.... Bad ecu is all I can think of left, after that I'm lost and will no doubt have to take it to the miserable dealer....

 

[chudson1549]

Weird...and you checked the fuse to the comptech fmu behind the drivers side seat?