Car starts and runs(poorly) without fuel pump fuse...

[myRed240]

Ok, school is out now and I have more time to tackle this annoying problem:

My car starts only with the fuel pump fuse removed. It runs terribly, but runs nonetheless. If the fuse is in, it floods the motor and won't start. If I start the car(fuse out) and then put the fuse back in, it floods and dies.

The following are the added/upgraded parts related to this problem:

Enthalpy ECU (tuned for the following parts)Walbro fuel pumpZ32 fuel filterZ32 mafsDW 555cc injectors

I've checked the O-rings and they look just fine. I haven't been able to pull the fuel rail yet, but I feel like the O-rings looked good as new so I don't know if this is necessary. Is it possible that the MAF is bad and even upon startup it's causes this?

Time for some input. I really only have a couple weeks before school starts and I need to get the car running so I can figure out any other bugs in the system.

Thanks in advance!!!

-Alex

Modified by myRed240 at 12:44 PM 12/23/2006
Modified by myRed240 at 4:06 PM 12/23/2006

[Florida240sx]

Checked your timing? Maybe dizzy is cracked? What's your fuel pressure? Got you fuel lines hooked up correctly? Open the ECU check to make sure the 2 black chips are pressed into the board... Somtmes in shipping they wiggle loose

[Acecool]

You need a fuel pressure regulator that you can limit fuel with.

[myRed240]

I didn't mess with timing, would this still be a problem? Dizzy is lookin' good, fuel lines are good, I'll check the ecu though.

Do I really need an adjustable FPR? I was under the impression that many people were running a very similar set-up without a FPR. Can folks chime in regarding the FPR?

THanks again.....

[TheOne]

you do need a fuel pressure regulator though, either your stock 1 isn't workin or you don't have 1 at all.

i don't believe you have to do anything to the distributor though as you have an ethalpy ecu which should control the timing.

[jdm_master_X]

check your fuel pump wiring. it might be shorted to something else.

[Edub1]

Sounds like a bad pressure regulator or perhaps the vacuum line that goes to it. Check the FSM on how to test the fpr.

[jdm_master_X]

well its vacuum operated, so just apply vacuum with a handheld pump and watch the readings on the gauge if its applicable.

[C-Kwik]

Did you try the suggestions in your prior thread about this?

zerothread?id=208841

And if so, what were the results? To find the cause, you need to methodically eliminate each possibility and narrow it down.

[myRed240]

I've been unsuccesful at removing the fuel rail. There's one nut on the far left that I just can't get to. O-rings have been inspected several times and they look great. I've carefully removed them and re-lubed them each time and they look as good as the new ones that I bought (as a back up).I'll try the spark plug suggestion that you gave in previous thread.

The other problem that I'm having is that the car is not near my house (at an exhaust shop). It's about a 15 min highway drive away and I'm without a car while my wife is at work.

Like I said, school just ended so now I'm back to figuring this out....

Thanks again for the suggestions!

[Frozen240]

I would double-check the wiring of the MAF. I had a similar problem when I was trying to get my car to run after putting a JWT ecu in it. I had to wire one of the grounds from the MAF to the chassis, it would not run with both wired to the ecu. I can't recall which one it was of the top of my head. After that, it ran fine. Try searching for Z32 MAF wiring.

[S13FX]

check your fuel pump wiring. it might be shorted to something else.

Amen, you my friend have a short if the thing runs with out a fuse. So trace back your wiring and find it. It's really easy just time consuming.

[C-Kwik]

Amen, you my friend have a short if the thing runs with out a fuse. So trace back your wiring and find it. It's really easy just time consuming.

I doubt this. With the fuse in, it's flooding. If there was a short, it would run the same way with or without the fuse. I suspect fuel is leaking past o-rings or the injectors are bad. Keep in mind, that with the fuel pump fuse out, there is still some pressure in the lines and sometimes in the tank as well. Some fuel can also accumulate in the intake manifold allowing the motor to run without much fuel being added.

[S13FX]

Right I tottaly agree with C-Kwik, but tell me what is feeding the fuel from the tank into the fuel lines when the fuse is out. I understand there is pressure buildup in fuel lines now but from another post he explained that the car keeps running with out the fuse in there.

[Chezedik]

Sounds like a reg problem to me. Like it's not opening.

EDIT: That is of course, assuming the tune is right.

[Edub1]

Hell of a coincidence to get a mixture close enough to stoich to let it run without pressure. Anyway, I'd replace the FPR and go from there.

[C-Kwik]

Right I tottaly agree with C-Kwik, but tell me what is feeding the fuel from the tank into the fuel lines when the fuse is out. I understand there is pressure buildup in fuel lines now but from another post he explained that the car keeps running with out the fuse in there.

But with the fuse in, it floods the motor. There is something else going on here.

[myRed240]

Okay folks, I was able to work on my car today.

I started with the fuel pump and verified that it was wired properly.Then I did what C-Kwik said to do with the injectors and I was able to verify that there was no fuel spitting out of the cylinders. Then, I checked the ECU to make sure the chips hadn't come loose.

Finally, I re-checked the wiring of the MAFs and pulled one of the grounds from the ECU and put it to a chassis ground.

Then, with the MAFS removed, fuel pump fuse IN, I cranked it up and it started. Viola! It idled ALOT smoother, but only runs for ~ 20 secs and then dies. It starts right back up and does the same thing.

SO, to sum it up: I rewired MAFS (put one ground to chassis), MAF unplugged, fuse IN, started it and ran for 20 secs before dying. It runs very similar with the MAF plugged in.

Now it's really rich to the point that there was some fuel at the exhaust tip. But it consistently starts and runs for a little. Any other input as far as richness goes?

Thanks for all the help so far......

ps. as far as MAF wiring goes, I currently have the wires color matched. The ground to chassis is the second ground wire (pin D according to JWT's diagram)
Modified by myRed240 at 6:09 PM 12/20/2006

[Chezedik]

Ah, I recently ran into the same issue. What color did you match the white wire to on your MAF?

[myRed240]

I believe I went white to white. White from MAF, which I was understand as ECU signal, to white on wiring harness to ECU. I copied the JWT wiring diagram and followed, as best as I could, the FSM wiring diagram.

To sum up my wiring:

JWT/FSM says: #### 0-5v out ## 12 volt ## Ground ## Ground

(S14) Car harness: ## white ## black/white ## black ##chassis ground to(Z32) MAF harness:## white ## black/white ## black ## orange

Bear with the oddness of the above, I'm trying to line everything up so that it can be read.

[Chezedik]

What rewiring did you do?

[myRed240]

I rewired the orange to chassis ground and that's it. Can you tell me how you have yours wired up?Thanks!
Modified by myRed240 at 10:23 AM 12/21/2006

[Edub1]

You are too lean. The motor starts because it is pumping in a pre determined amount of fuel. The car starts, burns that up and runs lean and dies. You probably have fouled plugs as well.

[Chezedik]

That's right.

[myRed240]

You are too lean. The motor starts because it is pumping in a pre determined amount of fuel. The car starts, burns that up and runs lean and dies. You probably have fouled plugs as well.

Oh, I'm sure the plugs are fouled. I have a new set that I was going to put in once this starting problem was sorted out.

So now it's too lean? What's the fix for this? I'm thinking it's the MAFS unless someone says otherwise.

So Cheze, are you saying your mafs is wired the same as mine?

Thanks again!

[C-Kwik]

It almost sounds like the tune is off on the ECU. It's a bit hard to tell without an oscilloscope, but it's possible that the duration of the injectors may be too long or the injectors are ground open by the ECU. Perhaps the injector grounds are shorted (but unlikely all four would be). This could explain why the motor can run for so long with the fuel pump fuse out. Some level of vacuum exists when cranking nd running the motor. With the injectors wide open, the vacuum can pull a small amount of fuel from the injectors, keeping the motor running (roughly). Checking for continuous ground will only require a multimeter to check continuity between the chassis ground and the injector grounds. Looking for duration will be harder, but checking resistance between the injector ground while it's running will tell you if the ECU is at least providing a pulsed signal.

Unplugging the MAF should result in a safe mode condition in which case if the tune is correct, it will at least idle well and rev up to 2500 RPM. Assuming of course Enthalpy didn't eliminate this feature and tuned it to run safe mode correctly with the larger injectors.

[Chezedik]

Yes, mine is supposed to be the same. I wired it a little wrong, but will correct it when I am done here. I thought the same thing about the tune. And stories have been leaking out as of late about problems with Enthalpy tunes, you will def have to get on the scope though to check pulsewidth. I have done the test and it's easy, but impossible without a scope.

[myRed240]

Unplugging the MAF should result in a safe mode condition in which case if the tune is correct, it will at least idle well and rev up to 2500 RPM. Assuming of course Enthalpy didn't eliminate this feature and tuned it to run safe mode correctly with the larger injectors.

It didn't exactly like it when I tried to rev it past 1500 rpms. I'll be able to do some more testing tomorrow, so that's when I'll see how it responds with the MAFS plugged in/unplugged. And I'll change the plugs to see if that helps. I'll also see if I can rev it up and note how my car responds to that as well.

I'll see about getting a scope, though I don't know anyone that has one lying around.

Any other tests that I can do to try and solve this problem?

THanks again!

Also, what effect will no O2 sensor and one vac line (to bov) have in this situation?I left the 02 sensor out while my engine was spitting fuel because I didn't want to buy a new one, I'll put it in tomorrow to see if that helps, and I'll remember to plug the vac line also.....


Modified by myRed240 at 2:40 PM 12/21/2006

[myRed240]

UPDATE

OKay, the car starts effortlessly now. It turned out to be a MAFS wiring problem.

Now I just need to figure out why it's running so rich. It idles right around 11.5-12ish on my wideband.

Here are current symptoms:

Idles/runs really richWhen I drive it normally, and let off gas it stalls unless I give it gas.The BOV (Greddy RS) is recirc'd before turbo/after MAFS, and it sounds like it flutters. I've done research, so I think I know how to figure that problem out.

The only thing I'd like some help with is the richness of my motor.

Thanks for all the help!!!

[Chezedik]

Retune with SAFC.