View Full Version : Help with S14 SR won't start, I'm stumped???

07-05-2006, 05:58 PM
Allright, this is driving me crazy, if anyone can help it would be you guys. I'm working on a customers car right now, its a 95 s14 with zenki s14 SR. He did the swap by himself, at first it wouldn't start, then he got it running for a few hours, he said it ran like crap and wouldn't rev above 4k, then it died and wouldn't start again. He worked on it for a few weeks and couldn't get it to run so he brought it to me.

So, Ive checked everything I can think of. Its getting fuel, fuel pressures good, injectors are all firing. Its getting spark on all 4 cylinders. I pulled the CAS and reinstalled it few times to make sure it wasn't timing. All the plugs are good, gaps are good, compressions good. ECU isn't throwing any codes. Ive checked the wiring and everything is good, everythings getting the power/ground/signal its suppossed to get. Relays are all good and getting power. Checked the CAS signal, tested the resistance on the coilpacks, etc, etc, etc.

In other words, Ive checked tested everything I can think of and can't find any problems. Only thing I can think of to do now is start swapping parts. I'm waiting on him to find another ECU, coilpacks, and CAS to try out.

One wierd thing did happen, when he first brought it in the fuel pump was working fine, would prime for a second when you put the key in the "on" position, etc. Then I went out one morning, put the key in, and nothing, it doesn't prime, doesn't come on when the engines cranking. I traced the problem back to the ECU and the problem ends up being that the ecu isn't sending the ground signal to the relay to turn the pump on and hasn't since then, everything else on the ecu seems to still be working fine though.

So at this point I'm just waiting for some parts to start swapping out. If anyone can think of anything else your opinion will be appreciated. Thanks.

07-05-2006, 11:14 PM
Any ideas?

07-06-2006, 01:23 AM
usually if there is a problem with a ecu, you can take the top of and look at the board and find the problem, just look for something that is burned or something that is not making good continuity, thats what happened with my buddies s14 ecu. does everything else come on when you move to the on position? have you tried swapping out the fuel pump relay? check the connections back at the fuel cell to make sure they are not corroded or loose? how about fuses? i know you probably did all this, but thats just the first couple things i would check if the fuel pump isnt running. one thing we did on one of our car was take a battery and open the trunk and run strait 12v to the pump to verify it was working. i think its the plug on the right if you are looking at it from the trunk. obviously dont let it continously run, we just made jumper wires and took the plug off and hooked them up to the connection on the fuel cell, then just touched them to the battery.

07-06-2006, 01:47 AM
You may also want to chack the FPR. These motors can sit for a great deal of time, the diaphram has been known to go bad.

07-06-2006, 02:08 AM
Yeah, I already opened up the ecu and didn't see anything out of the ordinary. The fuel pump problem is with the ecu, I traced the problem directly back to it, its not sending the signal to the fuel pump relay to turn the pump on. That much I know for sure. The pump, relay, etc, etc are all fine, I can signal the relay to turn the pump on manually, the ecu just isn't doing it like its suppossed to. And yes, everything else is getting power like it says in the first post.

I have also unplugged the vaccum line from the fpr to test that out, with no changes at all.

07-06-2006, 02:21 AM
Kind of silly, but do you have the connector tightened down to the ECU all the way?

07-06-2006, 02:26 AM
Any ideas?
zenki s14 ecu is very picky with what mafs one uses.
incorrect mafs might be the cause of crappy performance.

as for the fuel pump issue, a short in f.p. circuit can kill the f.p. driver in ecu.

07-06-2006, 02:27 AM
Yeah, everything is tightened down, Ive been over the whole harness 2-3 times now and its good. Its getting spark, everythings getting power, CAS is sending signals to the ecu, everything is working (except the fuel pump, I have to hardwire that for now).

07-06-2006, 02:30 AM
Yeah, I kinda figured the fuel pump circuit in the ecu was gone or somthing. Ive actually been trying to get it to start with maf unplugged, I tried it several times with the maf plugged in as well though, no difference. I just want the damn thing to run right now, troubleshooting problems after its running is a different story.

07-06-2006, 11:01 AM
BTW, just pulled the fuel pressure gauge off my car and put it in his so I could be totally positive fuel pressre was good and it is. So fuel is definitly not the problem.

07-07-2006, 01:58 AM
BTW, just pulled the fuel pressure gauge off my car and put it in his so I could be totally positive fuel pressre was good and it is. So fuel is definitly not the problem.
I have the same prob with one of my s14 ecu. only thing is i dont have a harness to test or a s14 engine.it is just a spare ecu i have laying around for when i tune stock computers.. my ecu still works perfect other than the fuel pump will not turn on from the ecu. but if i put power to the fuel pump on manually and use the same ecu the car runs fine. i havent had time to go back and find out. i will research when i have time and a need to fix the prob. if i fix it i will let you know.

07-07-2006, 07:50 PM
After about a full week of troubleshooting, mine came down to a lose wire in the ecu which lost one of the clips. Basically, when i jiggled the harness something new would turn on. First, the fuel pump wouldn't turn on even with a signal going to the pump and then the safc wouldn't turn back on. Definitely check the harness or the clips on that ecu. Wiring is defintely a B!%$* in my book.

Are you getting full cabin power while the car is on ign?

07-07-2006, 08:38 PM
The fuel pump problem is not with the harness, Ive checked the signal directly on the ecu and its not there. Other than that everything is getting power, I'm not having any electrical problems at all.

07-08-2006, 12:57 AM
Allright guys, I swapped the CAS and coilpacks, opened up the coil pack harness and regrounded them to the chassis and engine with some thicker guage wire so its getting really good spark now. I got it to start and run for about 30 seconds but then it stumbled and died and won't start again. I think it flooded itself and died. Plugs and cylinders were wet but not enough for any kind of pooling of fuel. So, what could cause that? I checked the injectors, they aren't leaking, fuel pressure is perfect, I pulled the valve cover so I could be positive the CAS wasn't a tooth off and its perfect. Any ideas?

07-10-2006, 07:01 PM
So far Ive swapped the injectors,CAS, and coilpacks as well with no difference. Any other ideas?

07-10-2006, 11:05 PM
OK, so to summerize what has been checked:

-fuel system (fuel pressures good/injectors replaced/etc.)
-ignition system (coilpacks and CAS replaced, timing checked numerous times)
-Piping is all good, not clogged or anything, I tried it with and without the MAF plugged in with no difference.
-ECU is throwing no codes
-Compression is good
-checked all input/output signals on ECU according to fsm spec, they are all good
-All grounds are good
-Checked pretty much every sensor on the engine and they are all getting power and working

So, engine is getting good fuel and good spark, compressions great, timing is right, everythings working, and the damn thing will not start. If I crank it for like 20 seconds straight it will catch and stumble a little but die after 1-2 seconds. Opening the throttle makes no difference. I can't find anything wrong with it, everything is working properly, it just won't start. Only thing I can think of to do is change the ecu, plugs and fuel filter, and possibly swap the ignitor out. The ecu passes all the tests, and the filter and plugs are new and its getting good spark so I don't really think they are the problem but this is last resort. I am totally stumped at this point, any ideas will be greatly appreciated. Thanks.

07-10-2006, 11:42 PM
I am not sure about Nissan, but Toyota ecu's were able to monitor spark, and if the engine flooded, it would stop the injectors from firing. Sounds like you have too big of injector, too small maf, or retuned ecu.

07-11-2006, 12:25 AM
No, everything is stock, ecu isn't retuned, Ive checked it and everything inside is stock as far as I can tell and the owner had previously swapped ecu's without any change before he brought it to me, I would still like to try another ecu though, but I really don't think thats the problem. The MAF isn't the issue, its stock, and even if it's bad, the car would still start and run. It might not run good with a bad maf but it wouldn't cause it not to start.

07-11-2006, 01:44 AM
You mentioned the plugs and cylinders were wet. How wet? Have you checked your injector O-rings?

Anyway, I'm going to go out on a limb here and tell you about a very similar problem I had with a customer's car, which was probably the most bizarre thing I've ever experienced. To this day I can't explain how it fixed itself, but I can tell you what I did that made a difference.

S13 SR into S14 chassis. Z32 MAF, stock injectors, Power FC, ebay intake and exh. manifolds, GT2871R .86. The car had all of the symptoms yours had. Was getting fuel, air, spark, but would not start. Out of desperation I unplugged all four injectors and tried to start it it. It actually ran. And ran well. Revved like normal. With no injectors plugged in. Plug the injectors in while running, the thing would stumble and die. I can only assume the cylinders were so flooded that the unburned gas was able to ignite and keep the car running. I pull the intake manifold looking for something, anything. Nothing. Now this car had VERY BADLY kinked heater hoses on the rear of the engine as you can see:


I then decided with the IM off it would be a good time to fix it, since it would have to be done anyway:


So after fixing this, the car started up and ran normal WITH the injectors plugged in. I don't know how hindering flow within the cooling passages affected anything, or even if it actually did affect anything. But after this was fixed, everything was good.

I know your probably thinking "how the hell could kinked heater hoses cause the cylinders to flood with gas?" I thought the same thing. Anyway I'm not sure if this helps, but it might be worth looking into.

07-11-2006, 01:54 AM
Thats the most screwed up thing, basically because his hoses are kinked too. Actually the upper radiator hose is kinked as well. I was gonna take care of those after I got it running. I'll definitly try unplugging the injectors and fixing those hoses though. It would be extremely badass if that worked. But yeah, I have checked the o-rings, they are good, no leaking. Plugs and cylinders are wet but not pooling fuel or anything, about what you'd expect from trying to start it so much.

07-11-2006, 05:04 AM
if you dont have enough coolant flowing over the sensor for a sr i know the car will idle like ****, but i have never seen it not start because of it thats weird. and i wouldnt put another ecu in the car that doesnt work because by the off chance the wiring is messed up you can short that one also, try taking his ecu out and installing it in another car.

07-11-2006, 10:25 AM
So what's the waveform off the CAS look like?

07-11-2006, 01:51 PM
Wiring was done by me and has been checked more than once, its not the problem. The car was running when he first did the swap, then it just died on him and hasn't started since. I have checked every power, ground, and signal on the ecu and they are fine. Plus everything is working, all the sensors, etc are getting the power they are suppossed to and turning on. I don't know what the waveform off the CAS looks like but Ive tried 2 different ones, one was from a running car and there was no difference, it is getting good, consistent spark.

07-11-2006, 06:34 PM
BTW, when I try to start it with the maf plugged in it throws the maf code on the ecu. I was gonna check that out after it was running but just wanted to make sure that doesn't have anything special to do with it not starting. Ive never seen a bad maf cause it not to start and it does the same thing regardless of if the maf is unplugged or plugged in.

07-13-2006, 10:16 PM
Im having same problem with 92 stanza. I checked everything. I'm getting gas, spark and timing is also functional. Sounds like im not getting any compression. It was running fine when i parked it no symptoms or anything but when i got back few hours later it wouldnt start. Its not even trying to start. Help.