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Help: Fuel Issue (I think)


quickdraw

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I've got an rb25det series 1 swapped into my 280z. I swapped in the motor, checked compressions and installed the fuel delivery among other things but wasn't comfortable with the turbo install, wiring and tune. So, I had HoustonZ do that work when I still lived in Houston. The car has run amazing for the last year...even on a high-speed road rally and a bunch of aggressive twisty driving since I've moved to Denver. 

 

Last weekend I pulled the car out of the garage to do some work on the garage itself. When I went to move the car back in it fired up quickly as it always has it died about 5 second in and hasn't started since.

 

This is my least capable area on the vehicle so I'm doing the youtube/home mechanic approach to troubleshooting with no success on identifying the problem:

  • I'm getting spark. I pulled cylinder #1 plug and watch for the spark, check.
  • When you turn on the key to on, the fuel pump sounds like it kicks on, check. 
  • When you attempt to crank it, it won't turn over and I hear a click, click, click noise from the pump area. After that I smell fuel towards the rear of the car. Not sure if that was always the case on start. 
  • I got a fuel pressure regulator from autozone, and tested the fuel pressure at the fuel rail (opposite end from the regulator) and no pressure. It's a stock Rb rail. Am I supposed to have pressure on attempted crank? If so, I'm not getting any. 
  • If I just hold the rubber fuel lines under attempted crank there's not a consistent pressure on the line...more of a pulsing feeling. 
  • I pulled out the multimeter to check the fuel pump- red wire on the positive and black on the frame 0.0 V with the key turned to the on position. Does that mean the pump's bad?
  • Next up is to unflood the engine just to make sure but that doesn't seem right and check the voltage at the pump with someone cranking. 

Seems like a bad fuel pump but it's new with 4K miles on it. So, odd. Anything else you guys would recommend checking?

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Hmm what fuel pump?

 

Do you have an inline fuse for the pump? 

 

Stock ECU?

 

Some thoughts.

 

Smell of fuel sounds like a simple fuel leak.

 

Click click sound, sounds like you could have snapped an impeller in the pump. Probably not the case since you say you an still hear it priming.

 

No voltage with initial key on sounds like you may have blown a fuse. Except the pump runs on initial key on, probably your ECU not running the pump, that is pretty standard for most ECU's after priming if the engine is not sending a crank signal.

 

Fuel pressure gauge would be before the regulator on the feed line pretty much anywhere. You should have pressure before and during cranking, granted some regulators don't hold residual and will drain fairly quickly after the initial priming. If you don't then that makes me think you dropped a fuel line somewhere.

 

After getting the fuel pressure gauge installed, run a positive 12volt constant connection and run it to the fuel pump and see if you build any pressure. If you do, then your ECU or fuse is preventing the pump from running. If you don't build any pressure I would think of a loose fuel line fitting, crack in the hose, or something physically wrong with the system including a potential bad fuel pump. 

 

Word of advice when you do things like run constant power, make sure to throw a switch in it so you can shut it off from the engine bay so you don't have to run all the way to the back of the car if something goes bad.

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Oh I misread that. Did you plumb in two fuel pressure regulators now? You shouldn't have two pressure regulators in series if that is what you did.

 

Short of an injector sticking open I don't think you would flood your engine. Granted that could explain where the fuel is going if the pump is running and you have no leaks and don't build any pressure.

Edited by seattlejester
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Oh I misread that. Did you plumb in two fuel pressure regulators now? You shouldn't have two pressure regulators in series if that is what you did.

 

Short of an injector sticking open I don't think you would flood your engine. Granted that could explain where the fuel is going if the pump is running and you have no leaks and don't build any pressure until suddenly.

Nope...just one regulator.

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Ah the line "I got a fuel pressure regulator from autozone" made me rethink what I read. Looks like you meant fuel pressure gauge not regulator.

 

What does confirm power mean? That you ran a new line? Or just that you checked the power with the multimeter?

 

Well seems like you may be on your way to figuring it out. Good on ya!

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Ah the line "I got a fuel pressure regulator from autozone" made me rethink what I read. Looks like you meant fuel pressure gauge not regulator.

 

What does confirm power mean? That you ran a new line? Or just that you checked the power with the multimeter?

 

Well seems like you may be on your way to figuring it out. Good on ya!

oh...I missed that. Definitely gauge not regulator. Confirmed power at the pump with the multimeter. Swapped out the fuel pump today and have pressure again but still not firing. The plugs are pretty dirty. So, going to swap those out tomorrow. 

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Fingers crossed. 

Ok. first off, your original post you stated the car is not turning over. This would lead me back to a battery/terminal issue, not fuel related. 

 

Lets get things straight, when you turn the key to start it, does it turn over and do so strongly?

 

The way the stock ECU works is that when you first turn the key to the "ON" position, it runs the pump for 2-3 seconds. It won't do it again unless you turn the key to off for like 15 seconds (try to go back to "on" too soon and it won't prime the pump again). Also, it's very unlikely you flooded the engine on an EFI engine provided you do have spark. If you do in fact have spark, then when your pump starts working, it would fire right up. Also, pretty unlikely that your plugs fouled enough to stop it from starting. Yes fouled plugs can cause misfires under higher loads, but the spark required to start the engine isn't that much.

 

But get back to us on the engine turning over first and lets work from there.

Edited by mtnickel
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  • 2 weeks later...

Ok. first off, your original post you stated the car is not turning over. This would lead me back to a battery/terminal issue, not fuel related. 

 

Lets get things straight, when you turn the key to start it, does it turn over and do so strongly?

 

The way the stock ECU works is that when you first turn the key to the "ON" position, it runs the pump for 2-3 seconds. It won't do it again unless you turn the key to off for like 15 seconds (try to go back to "on" too soon and it won't prime the pump again). Also, it's very unlikely you flooded the engine on an EFI engine provided you do have spark. If you do in fact have spark, then when your pump starts working, it would fire right up. Also, pretty unlikely that your plugs fouled enough to stop it from starting. Yes fouled plugs can cause misfires under higher loads, but the spark required to start the engine isn't that much.

 

But get back to us on the engine turning over first and lets work from there.

 

It's turning over and running a nistune modified z31 board. Turned out to be fouled plugs. Replaced those and it fired right up.

 

I guess the autozone fuel pressure gauge was bad which is weird and cost me an extra fuel pump. So I have a perfectly good Walbro inline 255 if anyone's itching for one. The larger issue turns out is that brand new plugs got fouled after 4K miles. Pretty sure the valve seals are bad on the RB. It answer the question on why it stopped running immediately after I overfilled the oil, explains the white smoke and the oil shooting out the tail pipe under hard acceleration (newly discovered). Fun. 

 

Anyone bored and want to help rebuild an rb in Denver? I was going to do a stock internal upgrade at some point so...while I'm in there...

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