Coatchawa

Hello all.

Rescued a rust-free 1990 v6 Firebird before it was taken off to the local Pull-A-Part. Too cool-looking of a car to scrap.

I know the previous owner, and they said last time it was on the road was this past winter - so, less than a year. However, the last year on the tags it had was 2013, so they may have been mistaken. It has been sitting because of a bad fuel pump.

I confirmed a bad fuel pump, and replaced the fuel pump. The fuel pump now runs and delivers proper pressure to the engine bay when the key is turned, and while cranking. The car will also start with a squirt of starting fluid. However, the car will not run on it's own gasoline, despite having proper pressure at the schrader valve in the engine bay.

So....
- Fuel pump is running at the correct times
- Fuel pump is delivering proper pressure while cranking
- Car is making spark
- Car will run off of starting fluid
- Gas is returning to the tank through the return line, so I know the lines are clear
- Every fuse, including the one in the fender well has tested good

But the car will not run. I will be consulting my Haynes and Chilton manuals over the next hour or two for some ideas, but I figured I would post my question here as well, hopefully for some real-world experience. Thank you all.

Tuned Performance

iTrader: (92)

Vats or injectors are plugged.

Coatchawa

VATS seems fine, and injectors could be a possibility. But, I can understand one, two, or maybe even three injectors clogging at a time if the stars aligned, but out of six, there should be at least one firing, shouldn't there? But there isn't even a single fire while cranking

RBob

iTrader: (1)

If they are the OEM Multec injectors the coils are likely shorting out. This prevents the injector driver from firing any of them. So common I'm tired of typing this.

RBob.

Coatchawa

Thanks for the point in the right direction, I'll do some searching on that.

Next time I'm at the car, I'm going to test for injector pulse, and that'll tell me quite a bit. After consulting my manuals, Ive concluded the following.

If I have injector pulses, the problem could be:
- All 6 injectors are clogged at the same time (unlikely)

If I do not have injector pulses, the problem could be:
- ICP in Disty
- VATS, despite no flashing light
- ECM

LiveIt!

You need to find out if your injectors are getting any pulses while cranking, I bet the problem is further up the line somewhere. My car acted just like this after I saved it from the scrapyard and put a new fuel pump in; my issue was the injectors wern't firing, only priming. My problem was a disconnected wire that gives power to the junction box by the battery. You tested the fuses in the fender, but are they getting power?

Coatchawa

Just got back from working on the Firebird.

I have determined that I do indeed have injector pulse.

I wired the fuel pump to run at the relay, so I could hear it without the sound of the engine trying to start. This lead me to hear a loud hissing noise coming from the valley of the engine the entire time the fuel pump was engaged. Loud hissing starts once the fuel pump builds it's pressure, and it stays until a few seconds after you shut the fuel pump off.

I let it run like that for a couple of minutes, (the engine still isn't starting, mind you. I'm just letting the fuel pump run with the relay bypassed) and then checked the cylinders. What I am hearing is not a leaking injector, as I didn't have a cylinder filled with gasoline after letting the pump run like that. It is also not an external leak - there was no smell of gas nor sight of gas on the ground. This leaves me to believe that the fuel pressure regulator is allowing a restricted amount of fuel to return to the tank via the return line, but giving none to the engine.

Looks like I'll be taking the intake plenum off. I'll also replace the thermostat since it'll be easy access, and over the next couple of days, I'll think about also replacing the fuel injectors as well. Anything else handy to replace in this area while I'm in it?

Any other theories to the loud steady hissing sound coming from the engine bay while the fuel pump is engaged are welcome

Also, how complex are the fuel pressure regulators on these engines? If I buy just the rubber diaphragm, is it possible to detail and clean everything well enough to function properly? It looks to be maybe a couple metal pieces under tension of a spring. I can't imagine that re-buying those parts would make a difference

Coatchawa

After looking in my manual, I'm fairly certain my problem lies within the fuel pressure regulator, or the fuel block.

GeneralDisorder

iTrader: (1)

You need to check for injector pulse, and ohm the injectors as stated. The sound of fuel going through the regulator is normal. You are making this much too difficult. The regulator is unlikely to be the problem, and in any case you can simply hookup a pressure gauge to the shrader.

If you see a very weak injector pulse with a noid light or none at all then VATS is in play.

GD

Coatchawa

As I said in the last post - I have injector pulse. I didn't say I think I have injector pulse, but I said I have injector pulse. I cannot ohm the injectors without removing the plenum. But I'm not going to have 6 completely clogged injectors all of the sudden. Car was running with 6 good injectors under a year ago. If I had one good injector out of the 6, I would hear it trying to fire while cranking over. It's simply not logical to assume that 6 injectors can go from "fine" to "completely clogged and completely unusable" in under a year.

And no, the sound I'm hearing coming from the valley is not normal. I wouldn't mention it if it were a normal sound. It's something you'd clearly hear sitting next to someone at a red light. I am not overthinking, and I am not an idiot.

God, I hate forums. It's always someone telling the OP that they didn't properly search for other forums or research the internet, or a group of people talking down to someone asking for help. I've never understood the point of forums if all everyone is supposed to do is search from posts from the past. Where's the chance to build a community? I'm perfectly capable of troubleshooting and looking through my repair manuals, it would just be nice to hear other people's real-world experiences to go along with a car I've not worked on before. It's not just here. It's universal. And it's sad that positive functioning car communities are rare.

I bid you all adieu.

GeneralDisorder

iTrader: (1)

Yeah as I said you will still see some residual injector pulse on that model even when VATS is triggered.

You can easily put a fuel pressure gauge on the rail (to confirm rail pressure) and trigger the injectors one at a time with 12v to see if there's a pressure drop and they audibly click.

There is a systematic approach to be taken and jumping to the regulator without testing pressure is WRONG.

You are here asking for help. I have not only experience with this exact model and these exact tests, I'm also a professional diagnostic technician and shop owner. If my help is not appreciated then lots of luck to you.

GD

OrangeBird

iTrader: (1)

First things first ; Don't go getting yer panties all wadded up over the forum posts , not everyone reads the same posts the same way and folks here are generally some of the most helpful your gonna find on any chat board . For real .

Now , I'm not gonna beat you over the head with this , BUT , your taking a LOT for granted with the previous owner's obviously faulty memory when they say it was "On the road" a year ago , when the plates say 2013 ! Yes indeed , where we're now a breath away from 2018 that's a good 5 years that the car sat , and yes indeed 5 years is PLENTY enough time for the **** they sell as fuel these days to turn back into dinosaurs in your injectors , and yes that DOES mean all six of them .

If you truly have a proper injector pulse , and the rail is properly pressurized , and it will run with starting fluid , then the only logical diagnosis will be that the injectors , yes all six of em , are clogged due to the five year sit that the PO "thinks" is only a year .

South Bay Injectors is having a sale right now , and in your case that's exactly what I'd be looking into .....

JA411

Take a fuel sample, if still old fuel from 2013-2014 it would be bad. The sample should look and smell like gas, if it has a bad odor like turpintine or water in sample, it needs cleaning out of tank, lines and filter. If the spark plugs are getting wet during cranking the injectors would be firing.
Joe

OrangeBird

iTrader: (1)

In post #1 the original poster states that he replaced the fuel pump . Having done that , and he has confirmed that the pump does in fact pressurize the rail , I'd say he's well beyond the point of smelling gas in the tank since he very likely refilled the tank with new gas when the new pump went in .

Tuned Performance

iTrader: (92)

Then onto Post #4 , get a noid light and test for injector pulse. Or pull the plenum and ohm the injectors. Since they are multecs just replace them and go from there. Varnished fuel in the rail will cause them to plug the pintle.

zed-028

how did we get this far without looking at the ICM?

OrangeBird

iTrader: (1)

Post #7



Post #1


Um , ok , so now I think I see how a newby here could become a bit frustrated .......

zed-028

Newbie's getting frustrated? What about the people trying to decipher the nonsense spewing through the keyboard? in the very first post we have a combination of the following:

"Car will run off of starting fluid"
"the car will also start with a squirt of starting fluid"
"But the car will not run"

WTAF?

Mate, there are half a dozen decent suggestions here and blokes who will happily tell you about issues that have hit them in the past. You seem to be looking for a magic answer when its really more of a process of elimination.

If someone gives you a method to check something and it has some legitimacy, quit your bitching and give it a shot. If you don't like the advice then enjoy the fuel savings that can only come from having a 30 year old steel garden gnome on your lawn.

now that ive gotten that out of my system -

confirm that all your injectors arent clogged
confirm that your ICM isnt crapping out on you (its the worlds greatest killswitch)
and if all else fails, pull your exhaust before the cat, clean the plugs and hit the key.

OrangeBird

iTrader: (1)

Um , Zed , I don't know who you think your talking to here , but the OP left the thread 3 days ago , upset that folks didn't appear to be reading the ENTIRE thread before tossing out their helpful suggestions . For example ; When the Man said he HAS an injector pulse , not he THINKS he HAS , but that he does in fact HAVE said Injector pulse , just how many more times does someone HAVE to tell him to "check for an injector pulse" when he got past that back at post #7 ?????

In case you haven't read back through the thread that far , yet , here's when the OP said his goodbyes 3 days ago ;

Psst , I don't think hes coming back ........

GeneralDisorder

iTrader: (1)

But I have seen a noid light show an injector pulse on a 92 V6 when VATS was tripped. It wasn't very bright but if you don't know what the noid light should look like on that vehicle it can definitely send you down the wrong troubleshooting path. Especially if system voltage is already low as in most no start diagnostics due to sitting, being excessively cranked, or just natural starter draw while checking for injector pulse.

GD