Hello I was hoping anybody can lead me in the right direction I have a 92 rs Camaro 5 spd. I'm havin trouble with injectors pulsing I've replaved distributor including icm. I have checked ohms on injectors come out to 1.5 I believe.Also have replaced ecm. And I know the fuel pump is turning on I hear it buzz. Also have disconnected the fuel lines at the tbi and see its getting fuel. But still no injector pulse . I' can pour starting fluid in the tbi and it'll turn on but injectors won't Fire . I've checked fuses for injector and also made sure they have 12v with key in on position. I'm assuming it's a bad ground at ecm or wire going to ecm but anybody's input is appreciated. One last thing I was hearing my alternator buzzing when key in on position can a bad alternator cause injectors not to fire ?

 

I can't recall but I though tbi injectors were I. The 2.5 ohm range. Never the less Un plugging them both and testing with a noid light will work shorted injectors will cause the injector driver to turn off. Besides verifying power to the injectors, other possible causes vats, or icm or icm wiring to the ECM . You didn't mention testing vats voltage or hz to the 1228746 ECM or testing or checking the ECM grounds on the engine block.

 

Thanks for the reply. Well I actually rechecked the resistance on my injectors they were 2.4 ohms so that must be ok? Also I've by passed vats car cranks just no fuel pulse. Also where exactly is the ground on the engine block

 

On the rear of the passengers cylinder head D1,A11 of the ECM. Vats will be 2.5-5v to B6 or a hz signal 30 or 50hz at 50/60%. If the prom is removed the ECM goes into lhm and should pulse the injector to iliminate a vats issue.

 

I will check that tomorrow . Can the clutch have anythin to do with it? Because the other day they happened to just randomly come on and pulse but car was not running right was blowing a lot of black smoke . And stalled letting go if the clutch in neutral. Next day I went to crank and haven't gotten pulse again

 

Putting the engine under a load when the clutch is disengaged and the engine was loading up would not create the injectors from pulsing. Low fuel pressure they will still pulse but not really spray more of a dribble at the most.

 

Do you have spark when you don't have injector pulse? No spark, no pulse probably equals defective distributor or defective wiring from distributor to ECM.

If you have spark, but no pulse, the diagnosis will be different.

 

You can still have spark and no injector pulse and have a defective icm ? How does diagnostic differ ?

 

Well yeah I'm sure I have spark if I pour gas in the tbi I get the car to turn over . I have new distributor and icm . Also ecm and prom Car cranks so I don't think its vats problem. And security light does not stay on. Is the ecm ground the flat wire looking cable that runs to fire wall?

 

ECM, not ICM. I'll consider unusual failure modes, but if there's spark, I'd think the ignition module is likely OK. Put another way: If there's spark, the ignition module (ICM) is NOT the next thing I suspect or test.

No spark, no fuel pulse = probable distributor or distributor harness issue. The ECM is not receiving crank signal; or ECM jis unable to process the crank signal.

Spark but no fuel pulse = probable injector, injector harness, or injector-pulse-processing problem in the ECM.



I'd like to know:

1. if a 'noid light pulses--which might verify an injector solenoid problem, ruling-out the harness and ECM, along with ruling-out a distributor and distributor harness issue.

2. If the injectors have power supplied by the harness when the ignition is on. The injectors should be powered when the key is "on" or in "crank", while the ECM controls the ground to cause them to pulse (spray).

 

I am having the same problem. I hooked up the test lights and I only get them to come on after I have primed the motor and gotten it to turn over. I now also got the injectors to spray (@WOT) after being primed and started, but it quickly die because they will not spray at Idle. I have also replaced the ICM, I have a brand new fuel pump/ fuel sender assembly, new fuel filter, and new fuel lines. I have also checked and replaced the 20A fuse next to the battery and it was and is good. But still wont fire up and idle. Should I replace the ECM? or the Fuel relay? I know I am getting fuel to the motor because the injectors will spray just for a little bit after it is on. Please help. Sorry If I Have Hijacked the thread.

 

So I had it a shop for 2 weeks they couldn't figure anything out. I did notice they cut into the green/while cable from the fuel pump relay and wired it back straight to the ECM is that ok? . I'm thinking about just taking it to another shop I just really need my car back on the road to get to work

 

Priming should have nothing to do with injector pulse. Cranking the engine has EVERYTHING to do with injector pulse. The injectors won't pulse if the engine isn't providing a crank signal via the pickup coil and ignition module.

See above advice: Do you have spark when you don't have injector pulse?

They've had it two weeks and can't figure this out? YOU NEED A DIFFERENT SHOP. They should not charge you for their failure to figure this out, too. Ask 'em why they "wired it back straight to the ECM", too. You may want to have them repair this before you accept possession of the vehicle.

 

Yes I have spark when it cranks. Also the injectors do pulse and shoot fuel once the motor has been started using ether. but dies off. I have replaced the fuel pressure regulator just to make sure the pressure is good at the injectors. I am picking up my fuel pump relay today. I have replaced the ICM but not the Coil. Is that something that could cause it not to work? Maybe this weekend I will replace the distributor cap and see if that helps along with replacing the spark plugs and wires.

 

What is the fuel pressure when the engine is first started, and while running? This is sounding less like an injector-pulse issue, and more like a fuel-pressure issue.

Does the fuel pump run for two seconds when the key is turned "on"?

I'm suspecting (but cannot verify) that the pump doesn't run until the engine has oil pressure--a fuel pump relay circuit fault.


If you have good spark, and the ignition module hasn't died recently, the ignition coil is probably fine. WHY did you replace the ignition module?

Verifying that the cap, rotor, plugs and plug wires are usable is a fine idea. I've seen TBI distributor caps and rotors that are so worn-out it's a miracle that the engine runs.

 

I can not hear it turn on until the motor is primed and turned over. once it dies you can hear the fuel pump for a bit then it shuts off. I do not know the pressures I will check and let you know. I will replace the fuel pump relay today when I get home. I replaced the ICM because that is what the guy at Oreilly's told me that it could be the problem. this is my first SBC. I am an LS guy and have no clue about these distributors.

 

check ya fuses under the dash i know mine had a fuse for the a+b injector it popped and i had no injector pulse

 

I checked the fuses yesterday and they are all fine.

 

I checked my injectors with a noid light . The light only some seems to flash sometimes it did flash sometimes when cranking . also the car kept pulsing yesterday but when I went today to turn on again no fuel injector pulse?

 

Can a weak battery cause no injecyor pulse . It has 12.5 volts but idk seems to only pulse injectors when I'm gegting it jump started

 

very well could be a low battery problem or might have a grounding problem and is receiving the ground from the other vehicle and trying to use it, ive seen this happen a few times on alotta newer vehicles where there all aluminum blocks and transmissions

 

Define "primed". WHAT is being "primed"? HOW is it being "primed"?

If the fuel pump doesn't run until the engine has oil pressure, the fuel pump relay circuit is defective--which may or may not be the relay itself. Could just as easily be a broken wire, or faulty ECM.

 

Ok one last quick question before i take it to another shop . Can a bad instrument panel cause this. I noticed my instrument panel acting weird at times before the car gave out . And If I would push on it a bit it would start working again. My tach is pegged out when the car does finally tirn on. But at 0 when off. Can this cause a no spark which will cause the imjectors not to pulse?

 

also one thing i have read thru another forum that the tbi also the oil pressure sensor can cause a fuel pump not to work maybe it could be that i read that in a tbi to carb thread

 

I was Using Ether or Gas. I replaced the Fuel Pump relay thinking that was it but found out that the relay isn't getting the signal to flip so now I am thinking I am having a wiring issue or a faulty ECM. I also had that happen to me Tonyy_Z with the noid light, It flickered for a moment but the injectors never fired fuel. I will hard wire my pump this coming weekend and replace the ECM and let you guys know what happens. I have also read about the oil pressure sensor shutting the fuel system on or off, but I have also heard that it is a myth. Should I replace it first to check and see if that is the problem? What are yalls thoughts?

 

The oil pressure sensor can turn the fuel pump ON. It is NOT designed to turn the pump OFF, except that it will stop supplying power when the oil pressure drops--for instance, if the engine stalls.

The oil pressure sensor is a "back-up", supplementing the fuel pump relay. Under normal circumstances, the fuel pump is powered by the relay. If the relay fails, or the harness is defective--or the ECM fails to send the "turn-on" signal to the relay--the fuel pump is still powered by the oil pressure sensor but the engine will have to crank over long enough to develop oil pressure before the fuel pump will supply fuel. This leads to long crank-time before the engine will run. Adding ether or gasoline manually will speed-up the engine starting. Once the engine has oil pressure, the fuel pump would run, and the engine should continue running until you deliberately shut it off.

 

Okay that would explain why the injectors started to fire after the engine was primed and started. So it is more than likely the ECM, correct? Or is it a wiring problem? How would I determine either or?

 

You are confusing "injectors firing" with "injectors spraying fuel".

The injectors are almost certainly "firing" before the fuel pump turns on to supply fuel to the injectors.

You cannot determine where the fault is without tracing the wiring. If the wiring is good, the ECM is then suspect. The factory service manual should have an appropriate procedure.

 

Was told by another shop two of the purple and white wires were mixed up hopefully I get it fixed soon

 

Okay. I have replaced My ECM and now the Fuel Pump Kicks on and I have Plenty Of Pressure up to the Fuel Rail. Quick recap of everything that has been replaced so far.

Fuel Lines
Fuel Sender Assembly
Fuel pump
Fuel Filter
Fuel Pressure Regulator
Fuel pump relay
ECM
Distributor Cap/Rotor
ICM

The injectors are still not spraying!!!! Did another Noid Light Test and they do not light up when cranking. I have also pulled all of the fuses and checked / replaced them. I did find two vacuum lines that I have absolutely no clue where they go. Could these lines not being hooked up be the reason The injectors are not firing? I am all out of Ideas besides replacing the Injectors to see if that is it, but I am not even getting a signal to them. Please help!!

 

You never stated if the ECM is receiving the pass key hz signal !

 

Was this car running ok then the problem just happen suddenly? Or was something replaced or repaired then it happened? This problem is sounding like a missing or loose ground wire.

 

How do I check that?

 

I bought this car last month from a guy who had it sitting since 2003. I have drained and flushed everything. I have cleaned it up and replaced everything that has been obvious or I have found out was broken up until now. He said that the car was running them he messed with something and then it stopped running.

 

That's bad news you and the rest of us are going in blind without having the car right in front of us... my best guess from the symptoms you are describing would be he left off a ground wire. Just gotta start from scratch no fast fix I would go back to the basics, which would be make sure you got all your power and ground circuits working.

 

try checking for codes even if batt died, and you try to start it you should get codes. there is also a problem with most of the wiring harness's with these cars behind distributor the injector wires are soldered and they are just taped so they deteriorate

 

I tried checking the codes but for some reason the obd port is not working or not allowing it to be read. Also we checked the wires and the hot wires going to the Injectors are good showing 12V but the grounds are not getting a signal. I am going to try and trace the wire today or tomorrow to see if it is cut or came undone. If it is okay what would cause the ECM not to send out that signal? When we pulled the Dash we did find a resistor that someone had spliced into the line. I am not sure what it was going to. They were a yellow wire and a green wire. Could this be a VATS Problem? I am going to call the dealership today to see if this was a VATS car and get a Key if it was. The engine does crank just fine just not getting fuel. Also is there a way to bypass something to get the injectors to turn on?

 

Read post 4 again !

 

Put the resistor back and relearn vats system. There is a procedure for it and you can do it at home make sure everything goes back the way it was. this is most certainly what's causing your problem (if you took it out) also check the resistor there are numbers on it that tell you the value if your not getting that value resistors bad. you can get new ones at radio shack. good luck

 

The resistor has been hooked up with all the testing that I have done. I just recently took it out. It was the very last thing that I have done. I will take a pic and post a pic of it on here. This was some backwoods kinda stuff. they had the cap that protected the resistor off and it was just sitting out in the open, and they gooped up the whole damn thing with some black crap to where you wouldn't be able to see if it had writing on it or not. I called the Chevy House and the guy was arguing with me that my car did not have VATS( Which I know it does). Would it just be easier to order a whole new set of keys and replace the ignition switch along with it? Also I though that the VATS system shut down spark and fuel. Could they somehow have bypassed the spark and just not got the fuel bypass right?

 

you can have the vats deleted from your computer a lot cheaper than replacing everything. Vats only shuts off fuel in this instance , this runs with carb cleaner ? to measure resistor, take a multi meter put it on the ohm setting (horseshoe)touch each terminal to each side of key do not touch metal this will cause false readings. Write down value and you can get a new resistor at RadioShack.

 

Yes the car will run off of carb cleaner/ ether / gasoline. They car did not come with a VATS Key. I only have the backup key. Is there a way to bypass it without knowing the value of the key? Or is there another way for me to test it? Or should I just replace the entire key and ignition switch?