# B12 cranks but won't start



## Guest (Jan 20, 2003)

This post will be kinda long and detailed, so bear with me. 
I have an 1989 B12 5-speed that recently (about a week ago) began having a problem starting. It would crank away, but would never start fully. Every now and then I got it to actually start by fooling around with the plug wires, so I replaced those, the distributor cap, and the rotor. When this didn't solve the problem, I swapped ignition coils with another B12 and it still wouldn't start. I've replaced the battery with a more powerful one and that didn't help either. Every time I've gotten it to start, it runs perfectly...no choppiness, bad idle speed or anything like that. The fuel pump pressurizes to 14 psi near the throttle-body injector, and since the car runs fine when started, I didn't think that would be the problem. Also I doubt it's the crank sensor or anything like that or else my car probably wouldn't have run "fine." The last time I got it to start, I had to have my dad push me from behind with his car and I popped the clutch. I've been unable to start it since then. I took the spark plugs out and they were fine except the gap was a bit off, so I re-gapped them and put them back in. I've done some probing around with a test light and just about everything is good (ignition switch, etc). Some things I found that were concerning was that the harness going into the throttle body injector has no power to it, even when cranking. Just about none of the harnesses near the throttle body have power. After this, I sprayed some starter fluid into the throttle body and tried to start it, and it started and ran for a bit, then died. So the problem must be electrical to the fuel injector, but why the hell did the car run fine before? The more I find out, the more mysterious this all becomes to me. I'm nearly at my wit's end. I tried to check for codes in the computer, but the Hayne's manual is a piece of crap and not very informative. If I followed the procedure they outlined correctly, then my error code is 5 red flashes, then 5 green flashes, which isn't listed in the manual as a code. Any help, thoughts, or ideas would be greatly appreciated, I really need this car to work as I am very poor.


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## blownb310 (Jun 10, 2002)

Balefire said:


> *Some things I found that were concerning was that the harness going into the throttle body injector has no power to it, even when cranking. Just about none of the harnesses near the throttle body have power. After this, I sprayed some starter fluid into the throttle body and tried to start it, and it started and ran for a bit, then died. So the problem must be electrical to the fuel injector, but why the hell did the car run fine before? *


 *****You are right, the problem is an electrical problem to the fuel injector. There is a silver dropping resistor on the driver's side firewall. Two #3 phillips head screws attach it. Replace it. Your mysterious problem will go away.




> *the Hayne's manual is a piece of crap and not very informative. *


 *****Amen


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## AVERAGE (Aug 9, 2002)

all right well how about this... my car will not stay running at all now. i had an idling problem but only when it was warm for some reason. but now my car wont run at all. i have to constantly give it gas for it to run. at lights , i am holding the gas pedal down jsut enough so taht it wont cut off. i just recently replaced my pvc valve and the hose going to the valve cover which was rotted. since ive done this my car seems to be running worse. i checked to make sure that all the vacuum lines were reattached but she is just getting worse and worse everyday. im sick of it. about to throw the haynes manual in the air, put a few rounds in it, and take old faithful(not lately, though) to the dealership( que the evil music, lol) what advice do u have for me.


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## Guest (Jan 20, 2003)

*dropping resistor*

Ok, I think I found that dropping resistor, it's a large metal thing on the center of the firewall right behind the throttle body. I couldn't get it unscrewed (I bent a 12" screwdriver trying to get the screws out), but I hooked one end of the harness coming out of it to the positive battery terminal, then put a test light between the negative terminal and the other side of the harness. The light lit up, so whatever that metal thing is, it's conducting electricity just fine. The thing I tested is approximately 4 inches wide and about an inch high and is all silver on the outside. There is one wire going into it from one side of the harness, and another wire coming out back into the harness. If this isn't the dropping resistor, could you be a bit more specific where it is? (outside of firewall, inside the car behind the dash, etc?). I hate to bother with this, but if I can't figure this out, I'm going to have to get it to a shop somewhere and pay some jackass $70 /hour just to hook it up to the computer and tell me what the problem is.

Oh, also, I tested the harness that plugs into that metal thing, and I get no current through it at all, cranking or not.


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## blownb310 (Jun 10, 2002)

*Re: dropping resistor*

Yes, you found the dropping resistor. I just went into my ice cold garage to look up the voltage specs for you. But my '89 factory shop manual was not there, as I lent it out. In a nutshell, you should check it while it's all plugged in. There should be battery voltage going in, and quite a bit less [I don't have the book to tell ya] going out to the injector. If you don't have battery voltage going in, check your fusible links at the positive battery terminal. Let me know how it works out.


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## LittlebittaContact (Oct 12, 2002)

Code 55 (5 Red 5 Green) Means all systems Go.


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## Guest (Jan 24, 2003)

*little update*

Well, this is taking longer to fix than I anticipated with school being the way it is and it being about 0 degrees outside. I can only spend about 20 minutes poking and probing before I have to come in and warm up because I don't have a garage for this thing.

Anyway, I did some more testing tonight with a multimeter and found that the resistance from the dropping resistor is around 50 ohms, + or - a bit. I also found where the fuel injector wire goes into the computer and put a probe on the wire right by the harness. When the key is turned to ON, the wire has power, and while cranking, so at least it isn't the computer. When it warms up a bit I'll try to get that resistor unscrewed again, but just for verification, the fuel injector wire routes like this:

It is a black wire with a blue stripe, goes from the computer (ECM) to the dropping resistor, then to the fuel injector?

I still get nothing from the harness going to the resistor, cranking or not, so I'm thinking the wire may have been damaged somehow, somewhere. I was thinking of splicing a wire from the ECM straight to the injector to see if that fixes anything, but again I'll wait until it's warmer. Thanks for all your help with this guys!


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## Guest (Jan 25, 2003)

*PROBLEM FIXED!!*

Well, it's Saturday, and almost 30 degrees outside, so I finally figured out what the problem was.

Turns out that the harness going into the dropping resistor had a wire going to it that wasn't working or something. The wire going in was black with a red stripe, and the one coming out was black with a blue stripe (to fuel injector). Anyway, I observed on my brother's 1990 B12 that the black/red wire had constant power to it at all times...mine had nothing, ever.

Now I am the impatient type, and didn't feel like tracing 12 miles of black/red wire just to find out where the hell it came from, so I spliced it straight to the positive battery terminal (put a 15 amp fuse on the line too). This is pretty ghetto and may be bypassing some important sensor or circuitry somewhere, but I don't really care at this point. After I put a little starter fluid into the throttle body, it started right up and ran great. I've started it nearly 20 times now without fail, so I'm deeming the problem solved although I'm unsure what caused the problem in the first place. (bad wire, bad circuit the wire is on, etc).

I'll put some research into tracing that wire eventually, but probably not for a few months as long as the car works.

Thanks again for the help, especially blownb310 who pointed me in the right direction.


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## Guest (Jan 26, 2003)

Congratulations, I'm happy to hear another problem solved.


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## blownb310 (Jun 10, 2002)

*Re: PROBLEM FIXED!!*



Balefire said:


> *Thanks again for the help, especially blownb310 who pointed me in the right direction. *


 *****You are welcome. I was close anyway!


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## djmcd49 (Mar 19, 2004)

*'91 stanza*



blownb310 said:


> Yes, you found the dropping resistor. I just went into my ice cold garage to look up the voltage specs for you. But my '89 factory shop manual was not there, as I lent it out. In a nutshell, you should check it while it's all plugged in. There should be battery voltage going in, and quite a bit less [I don't have the book to tell ya] going out to the injector. If you don't have battery voltage going in, check your fusible links at the positive battery terminal. Let me know how it works out.


Anyone in this group any good with Stanza's?? I'm getting no fuel thru the fuel pressure regulator. plenty of fuel to it but nothing into the rail, therefore the car will not start. It kicks over with starting fluid, so I'm getting spark. Any help would be greatly appreciated. My son is getting sick of me using his car.


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## Inlinemotors (Nov 4, 2007)

*Need help 91 Z wont start.. AHH!*

Hey, I found this thread... I know its old, but i'm desperate for some guidance. I was connecting my injector wires, and accidentally, the positive wire touched a negative and made a small spark. ever since then, my car wont start. I dont even hear the fuel pump when I try to crank it.. I tried supplying direct power to the fuel pump and cranking at the same time, no luck!. ECU gives code 55. Whats going on here? anyone?


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## suditaki (Oct 31, 2007)

Inlinemotors said:


> Hey, I found this thread... I know its old, but i'm desperate for some guidance. I was connecting my injector wires, and accidentally, the positive wire touched a negative and made a small spark. ever since then, my car wont start. I dont even hear the fuel pump when I try to crank it.. I tried supplying direct power to the fuel pump and cranking at the same time, no luck!. ECU gives code 55. Whats going on here? anyone?


Check your fueses


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## blownb310 (Jun 10, 2002)

Inlinemotors said:


> Hey, I found this thread... I know its old, but i'm desperate for some guidance. I was connecting my injector wires, and accidentally, the positive wire touched a negative and made a small spark. ever since then, my car wont start. I dont even hear the fuel pump when I try to crank it.. I tried supplying direct power to the fuel pump and cranking at the same time, no luck!. ECU gives code 55. Whats going on here? anyone?


I'll try to help, but we will need more details. Is your car an '89 Sentra B12 5-speed like the origiinal poster's car in this thread? Why did you have the injector leads off in the first place?


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## Inlinemotors (Nov 4, 2007)

Hey, Thanks... No the car is a 91 Auto Z. The engine was hesitating sometimes, and when I called the person I bought it from, he said the injector wires might not be connected well, so I decided to redo them... then the power wire hit the negative and sparked, and now it just wont start.. when I turn the switch I don't hear the fuel pump..I checked the connection the fuel pump, and its not getting any power when I try to crank it. I thought it may be a fuel relay or something, I tried to bypass everything straight to the fuel pump, connecting power to fuel pump separately cause its not getting any power... and so i tapped a 12V while i had someone crank the car at the same time, I heard the fuel run all the way up to the silver resister... and the car still didn't start... i don't know if i fried my ECU or what when I was messing with the injectors.... what do you think is the problem?


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## blownb310 (Jun 10, 2002)

Oops, this is the Sentra forum, but I can tell you that your ecu is probably not fried because there is an orange safety relay that protects the eccs system. You must have fried something else though.


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## AVERAGE (Aug 9, 2002)

I think you posted in the wrong area :newbie:


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## blownb310 (Jun 10, 2002)

Be nice Average. At least he used the search button.


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## Inlinemotors (Nov 4, 2007)

Checked all the fuses, everything is okay...


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