Leaking fuel injector? Need help diagnosing symptoms

[Deadrodent]

Hey everyone my car's mileage has always been horrible but recently it's been really going down the tube..I got 165 miles on a full tank and I wasn't boosting much at all. I'm thinking it's a leaking fuel injector maybe multiple injectors...here are my symptoms:

1. black/grey liquid shoots out of my exhaust (if i hold my hand in front of the exhaust while the engine is on my hand gets plastered with little gray dots)

2. you can smell gas up to 15 feet away from my car

3. horrible mileage

4. car misses at high rpm (when i'm driving on the freeway and accelerate my car will literally pause and sound like it's choking for a brief nanosecond and then continue accelerating)

5. IACV keeps getting clogged

6. if i start the car multiple times in the same hour the car will often not start. i'll have to hold the gas and the car eventually starts...

i have a walbro fuel pump and 300zx fuel filter but other than that my fuel system is stock. i'll be checking the plugs soon to see what's going on but i'm guessing their fouled...

so what could be the problem? thanks in advace!

[Geno750]

Pull the fuel rail then turn the car to the on position and see if gas comes out. I had the same symptoms as your describing with my car once upon a time and it turned out to be a leaking injector o-ring on #4 cylinder.

The only symptom I had at the time, that you haven't mentioned, is when I shifted or let off the gas my car would backfire. I'm not talking about little atmospheric bov + maf backfires either; these sounded like I had a cannon in my car.

[Deadrodent]

is that the only way to test for a leaky injector? thanks for your reply man

bump for more advice! cmon nico people i need help
Modified by Deadrodent at 6:49 PM 10/22/2007

[wzntha]

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[Geno750]

I am also having similar problems with my car, and my fuel upgrades are also a 300zx fuel filter and a walbro fuel pump. when im on the freeway and im at 2000 to 3000 rpm, the engine seems like its choking. it would pause a bit and struggle to get to 3000 rpm, but once it passes that, it will run smoothly. this also happens when im going up a hill. there is a gas smell too, but i don't think its as bad as yours. im not sure if im getting bad mileage yet though, since i only had my car for a few days since i got a swap. the mechanics who did my swap says that the fuel pump might be installed wrong and they're gonna check it next week. if that is the case, i'll let you know if it relieves the problem.

The hose that goes from the fuel pump to the assembly that it sits on might be leaking, thats the only thing I can think of that would cause a problem that happens when your going up hill.

[wzntha]

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[jessej31]

Hi,I know this is an old post, but I'd like to know the results of your investigation, was it a leaky injector?

I am experiencing the same set of problems with my car....Thanks For your help!Sincerely,Dave HandsWestchester, NY

[duffman1278]

^^^^^ Have you checked the cylinders to see if their flooded? Try reading over this as well

1) Replace your plugs, make sure they're gapped correctly2) Check your fuel lines, make *sure* there are no leaks anywhere3) Check your fuel tank o-ring, replace it4) Check your injectors and o-rings5) Get a fuel pressure gauge. Make sure you do this before you get an FPR. A gauge costs ~$30; FPR costs at least $100, and you're going to need a gauge to adjust your fuel pressure anyway. Better to get the gauge first and then the FPR, rather than wasting $$$ on an FPR AND gauge and finding out that your fuel pressure is fine.

Edited for link to the bad Z place. Also, quoted the only useful post out of the 50 or so that were in the linked thread -Hijacker

[nxpoweredsr20]

a way to test is to pull out the spark plugs and see if the cylinders are full of fuel....if they are then one of the injectors o-rings may be pinched or cut......

[gezrez]

Hi

Can anyone help with nxr2000

I have had my injectors changed and they are still flooding cylinders 3 and 4. it runs ruff or desent start. mechanic want to change them again, i think its the computer, but he is sure its not. im not confident its the injectors the second time round.

iv replaced the fuel pump, electrical has been checked theres spark mechanical is ok as well.

Is there anyhting else i shoud be looking at sensors etc ?

[boro drift]

A lot of times, the old original fpr can't handle the output of a 255lph fuel pump. Check your fuel pressure.

[gezrez]

Apperently the fuel pressure has been checked and its ok, its all stock, the fuel pump is pretty much a replacement of the origianal spec.

[boro drift]

Pull the fuel rail, and with the injectors still in it, turn the key on to RUN, see if any injectors are leaking or open. If they dribble, the injector is bad, if it sprays a mist, then there could be a fault with the injector driver in the ecu, like you suspect.

[gezrez]

ok ill try that, will let you know how i go

thanks

[MTX450]

Any resolve to this?

[junyadee]

I am curious if there is any resolve here, I took my fuel rail out and my injector sprays gas when I turn the key on and when the key is off too and I realize its been doing this in the cylinder for some time, I am certain its not the seals (checked that) but with the computer out there is one injector plug that has a full 12 volt of power running through it. When I hook up my voltmeter to it I get a constant 12.5 volt through it and the other five doesn't even show .5 volt, what causes power to the injector when the key is not on and the ECu is sitting on the counter outside the car? I realized that when I pressurize the fuel rail and plug this one injector plug onto the injector it sprays and this is whats killing me because its the only fault I can see with my engine...Does anybody know what electrical item needs to be changed repaired or diagnosed to stop power from going to this one injector so it can stay close especially when the key is off? Does the ECU power the injectors alternately when you start the car? Why does this wire still have power to it when the ignition is off? This so frustrating, any help will be highly appreciated

[NISMOlvr]

I know this thread is 3 months old ,but just in case you havent resolved your leaking injector.Try changing ecu ,and if injector does not spray,then you know you have a bad ecu.also check your maf ,a dirty maf will give you a rich condition.Bad engine temp sensor also.For some of us with Z32 mafs:

I installed a n62 maf and followed JWolf website instructions ,(big mistake).My engine was running so fat rich.It would flood it.I had to remoove fpump fuse just to start it.After alot of brainstorming and checking voltages at ecu and grounds.I searched forums and found a thread with same prob, Jim wolf wiring diagram fail.Lesson learned.

when installing N62 MAF do not connect C and D ground wires on maf connector together.C goes to chassis ground.