justin57

Can anyone help? 89 Firebird 305 with TBI. It was running great. But my fuel gauge wasn't working. So I replaced the sender in the tank. Went ahead and replaced the fuel pump since it looked old as I didn't want to have to go back in there for a while. So it was back to running good and now my gauge worked.
I thought I was good mechanically so I spent a couple of weekends putting my interior back in and installed a stereo.
The next time I went to start it, it fired up and instantly died. After a couple of times of this now it won't start at all. I can throw some fuel in the throttle body and it will run a second or two and go dead, so I know I have spark. My fuel pump is working and I have fuel up to the throttle body.
My noid light flashes only once and very weak on each injector... not a continuous pulse. I tested the injectors with a 9 volt battery and they are both clicking.
I replaced the ignition control module, checked the fuse at the battery and the ones under the dash. I checked the engine ground. Still the same.I can't find the problem.
I thought I was ready to drive this thing and now this!
Can anyone offer some advice?
Thanks

antares57

iTrader: (8)

I'm assuming you put a new strainer on the fuel pump when you installed it. Did you replace the fuel filter as well? Have you been able to check fuel pressure (about 13psi)? Also, ohm your injectors (about 1.3), your coils may have gone bad. I just did a throttle body rebuild on my '88 TBI, it might help. Changed out the injector filters and o-rings, gaskets and new FPR diaphragm. Good luck.

justin57

Yes, I put in a new strainer. I didn't replace the fuel filter but I have bought one and will be installing it soon.I haven't checked my fuel pressure but I will as soon as I get a gauge. Thanks for the info on the psi. I knew it was more than for a carburetor but wasn't sure how much. I'm concerned about the limited and weak signal on my noid light and hope it doesn't have anything to do with an ECM problem. Anything else I'll be happy to deal with. I need to check those ohms also.Thanks

DynoDave43

iTrader: (11)

From what I've read, there's a rubber hose from the pump inside the tank. And it can split and leak off fuel pressure. Did you change that hose while you were in there?

Schurkey

Do you have voltage to the injectors? The computer switches the ground on and off to pulse the injectors, they should have voltage whenever the key is on, but they won't have ground without the computer circuits.

justin57

yes. The pump came with a new one.
Thanks

justin57

I'll check that tomorrow. I know I'm only getting one flash on the noid light but I need to check to voltage with the key on. I am also installing the new fuel filter tomorrow.

justin57

I have 9 volts on the injector wire connections with switch on and 1.8 ohms on each injectors. I replaced my fuel filter today. No change. It seems to me that it almost has to be my ECM. I might wrong, but I don't think fuel pressure would have anything to do with not having a pulse to the injectors. I found a used ECM on ebay. Should get it by next weekend. I have mine dropped out from under the dash, so next weekend I'll change that and see if it makes a difference.

Schurkey

Wouldn't it make more sense to verify that the wire harness from battery to injector is OK (9 volts is nothing to write home about--what is the voltage at the battery?) and that the wire harness from injector to ECM is OK?

justin57

I have 12 volts at the battery. Yes, I will check the wire harness. Thanks

Schurkey

12 volts at the battery means it's practically dead.

Charge the battery, let it sit for an hour. Retest at the battery (should be 12.6--12.7 after "resting" an hour after charging) and then turn on the ignition, test the battery again--may be down a tenth of a volt or so--and retest at the injectors.

I'd want as close to battery voltage (ignition on) at the injectors as possible.

justin57

I see. Thanks

justin57

Ok, I have just realized that my test meter is only working on the volt scale that rounds everything to the nearest volt. Time for a new one. So I can't get a reading in decimals.
But I charged my battery. After an hour it still reads 12 volts. I checked my juice to the injectors and I'm reading 11 volts. However, here's something else I've found.... According to what I've read on some other posts, I'm supposed to have power on both terminals of each injector with the switch on. Right? Well i don't..... I only have power on the red terminal of the drivers side injector and white terminal of the passengers side injector. So, what would cause this?

RFmaster

Measure voltage with respect to ground. When engine is not running, ignition is in RUN position you'll have 12 volts present at each injector posts (relative to ground) if the injector is plugged into the socket. If you remove injector plug off injector and repeat voltage measurement one of the two pins will measure +12Vdc the other one should be nothing. The 'nothing side' is the pin which ECM controls - pulling it to ground. TBI injector coil impedance is around 1.1 to 1.2 Ohm - which very low so that ECM has to switch plenty of current to activated.

Probably your sockets are not making good contact with injector pins.

//RF

justin57

Thanks

Jae992

I'm have this same issue I tested Ckt 430 12v battery test light to Ckt 430 on 4 wire connector no light ran a ground thro B5 and tested 430 it lights up does this mean my ecm is bad or wat other tests can I do

justin57

I don't know, but I put in another ECM and it didn't change anything. I just got out of my garage from changing the distributor and that didn't help either. (I have a used distributor from my 92 Silverado that I know is good). It still won't run. I'm just about ready to pull my hair out! If it weren't for the problem of my transmission not working right I'd be tempted to change everything over to a carburetor! But the TBI sure was running good until this. What kind of signal are you getting on your noid light? Mine flashes once weakly and then no more. I have a 98 Jimmy that I just recently had to solve the VATS problem by installing a replacement module. I keep thinking about how the Jimmy acted and it is exactly how my firebird is acting. However, from what I've read the two systems are not exactly the same. On the firebird I'm told the the VATS will always disable the starter whereas on the 98 Jimmy it will still crank but will not have any fuel to run. (If anyone knows any different from this please tell me).Going by this I hope I can rule out the VATS. If I knew for sure it would solve my problem I would gladly get another replacement module like it for my firebird. But I don't know what to check next. So your car has the same symptoms as mine? Maybe we can figure this out together.
Keep me posted.
Thanks

Jae992

When I put the test light in the terminal A it lights up when I crank engine the light stays lit but sort of dims does that mean anything? Idk what else to look for I'm stuck waiting on ideas and I don't wanna just change parts hoping it works

Schurkey

Two things pop immediately to mind:
1. The battery voltage is reduced because of the amperage demand of the starter motor, and
2. If you're testing that terminal while it's still connected to the injector, the ECM is supposed to be grounding that circuit in pulses, so the average voltage goes down.

Either or both could dim the test light. Both would be normal.

Damned good idea. Diagnose first, replace second.

Jae992

Ok I have a normal test light not a noid light am I testing correctly or should I get a noid

Schurkey

A noid light is nice because it tests both the supply and ground sides of the circuit.

Because the ground side of the circuit is what the ECM controls, knowing that the ground side works is essential.

Jae992

Ok I'll go pick one up

Jae992

Question my security light stays solid would that cause injectors not to spray? It cranks tho and ive researched conflicting answers

Schurkey

Might be time to buy a service manual.

Far as I know, the security system (VATS) will disable the fuel spray. Never worked on one.

justin57

Like I said earlier, I have worked on a VATS system in my 98 Jimmy. And it DID disable the fuel spray. Since your security light is on,I would strongly suspect that VATS may be the culprit. That was the case in my Jimmy. As a matter of fact, I'm beginning to suspect that it may be my problem in my Firebird because the symptoms are the same as in my Jimmy. The engine would crank and it would sometimes start for a second and might try to run while pumping the gas pedal.
Here's how I solved the problem: installed a replacement module from NEWROCKIES.
It worked perfectly. I ordered one yesterday for my Firebird. From what I have heard and read, it's only a matter of time before the VATS system causes a problem. And whether or not it's my problem right now, I have decided to rule it out as a possibilty while ensuring that I won't have a problem in the future.

Jae992

Yea I think I'm going to rule it out too because its bothering me PO said he fixed it yea I don't believe him I'll let you guys know if it fixes the issue

justin57

Thanks and I'll do the same. Mine should be here about Tuesday and I will install it next weekend. At least I will know that demon is not lurking in the shadows anymore!

justin57

Jae992, are you showing a code 53? I am. This is the code for a VATS problem. But just for the record, if your repair manual is an early edition it might just be listed as high voltage telling you to check your charging system. My security light does not come on and my ses light does not stay on. I have a found a used VATS module that matches my key ohms and it will be shipped to me soon. Since it will be a quick plug in fix I will try it first before installing my replacement module. If it works ok, I might just leave the factory module in place and keep my replacement for backup in case I ever have a problem again.
Hopefully next weekend I will be driving my car again.
Good luck.

Camaroguy94

Just went through something very similar with my 1990 camaro. It would crank and i had 12V to the injectors and everything seemed OK except that the injectors weren't firing fuel. I was losing my mind trying to find the problem. I read my code and i had the same code 53 for VATS and noticed that my security light stayed on which it shouldn't of course.
What i had to do was measure the resistance on my key on that little piece of metal housed inside the black plastic. http://www.vatskey.com/ this site explains it well.
Once you know what resistance value you have you can go to any radioshack and buy resistors that match the resistance that you measured for like 2 bucks then you have to put them into the connection from your lock cylinder to the VATS. its an orange wire with two white wires inside of it. http://i107.photobucket.com/albums/m...WS6mama001.jpg
should look like this.
for the time being you can just put the two ends of the resistors into the connection just to see if it works.
My car started right up once i did this hope it helps!!

Jae992

You beat me to it bro I literally just did exactly wat u said and its now testing correct it was vats just have to buy new injectors now old ones were shot thanks for confirming

justin57

Thanks guys. I didn't get to try that because as it turns out , I got home from work today and my replacement module had been delivered from Newrockies. I installed it and after a quick prayer for good measure, twisted the key and SHE FIRED UP!!!! So problem solved! I have to say that this has been the most frustrating thing this past month I've encountered in all my 40+ years of working on cars!
Boy, I'm going to have a great weekend. Now I can get back to putting the interior back together and take it for a drive.
I know the guy who came up with the VATS thing meant well but I would rather it had been left out of the car. Too much mysterious garbage going on! ( I'm just too "OLD SCHOOL" for so much electronics and computerization)
Take care and
Thanks for everyone's input