Fluffy6079

I have a '92 Firebird with a TBI 305. I bought the car for less than $1,000 a few weeks ago and have been in the process of trying to get it running in my spare time. I know that the vehicle had been sitting for a few years before I bought it, and I made the purchase knowing that it would be a project.

My car has a problem that I've seen addressed many times but one where fixes seem to be a grab bag of parts replacements or they just don't seem to be fixed at all. When I turn the key I can get it to crank, but it won't fire up. The injectors in the throttle body are not spraying any fuel. HOWEVER, if I spray starting fluid or pour a small amount of gasoline into the throttle body, the injectors start spraying and the car runs for a second or two before stalling out. At that point, I can usually start the car (with its subsequent stalling) without the aid of starter fluid or gasoline a few times before the injectors stop working again. When the car fires, I can prevent it from stalling by feathering the gas pedal, but it runs pretty rough.

I have replaced the following parts since owning the car:
*fuel pump (which needed to be rewired due to...I'm not really sure what the previous owner thought he was doing, but I basically had to remake the wiring harness)
*fuel pump fuse (it was initially blown)
*fuel filter
*ICM
*MAF burnoff relay (it wasn't working at all)
*IAC valve

My father-in-law even went as far as to take a throttle body and all its attached parts off of a vehicle we knew was running well and put it on my car to see what would happen and it continued to do the same thing.

brettr81

It doesn't seem like the fuel pump is priming. Seems as if the fuel pump is only running off the oil pressure switch.

Fluffy6079

The fuel pump is definitely priming. We tested it before installation and verify that it is priming before we try to start it.

RBob

iTrader: (1)

Sounds like a VATs issue. And your car doesn't have a MAF burn off relay, as it doesn't have a MAF sensor.

RBob.

Tuned Performance

iTrader: (92)

This thread has some testing info for vats .
https://www.thirdgen.org/forums/tbi/...o-350-tbi.html

https://www.thirdgen.org/vats_passkey_system/

Fluffy6079

Thank you very much. I just came in from fooling around with some things on it. I'll do some VATS tinkering next time I get some time. I also read that the oil pressure switch might be part of the problem. While I was out I used a wire to bypass the sensor to see if that would help, but there was no change. Here's hoping that VATS is the issue!

Fluffy6079

@RBob

What is the relay mounted beside the fuel pump relay? It's almost identical to the fuel pump relay. In fact, I can swap the plugs between the two with no issues.

Tuned Performance

iTrader: (92)

Fan

bluers91

Have you tried scanning for any codes? Does it show the SES or Security light?

henryd3

iTrader: (128)

If it's a VATS problem your security light should stay on and the starter won't crank over at all

bluers91

It all depends. There are two different VATS cutoffs. One at the starter and another that cuts fuel I believe. When my VATS has failed the security light comes on and the starter won't crank whatsoever. I've even had it happen once and VATS is disabled in my ECM.

Schurkey

That's exactly the first thing that comes to my mind, except that stalling after 2 seconds reminds me of VATS issues.

Let's start here: What is the fuel pressure during the two-second Key On, Engine Off prime cycle, and what is the fuel pressure as you crank the engine?

RBob

iTrader: (1)

Not sure which relay is which, but they are for the fuel pump, cooling fan, and A/C compressor clutch.

RBob.

henryd3

iTrader: (128)

The actual relays are the same but the fan relay has 4 wires to the connector and the fuel pump one has 5
OOPS, that's for a Camaro, not sure about Firebirds

Fluffy6079

Update: I bought a VATS bypass module and the thing fired right up. It ran very smoothly for a car that's been sitting up for a few years. I even drove it the 2 hours from my father-in-law's garage to my house. I pulled in the driveway and the radiator sprung a leak...lol. The journey continues. Thanks for the help.

DynoDave43

iTrader: (11)

Glad you found the issue Fluffy6079. I like the radiator problem...very straight forward!

two-if-by-sea

iTrader: (22)

What bypass module did you purchase to make it run?

Tuned Performance

iTrader: (92)

Here a few, painless offers one too.
http://m.ebay.com/itm/GM-VATS-or-PAS...%257Ciid%253A1
http://www.bakerelectronix.com/products_vats/

two-if-by-sea

iTrader: (22)

Thanks for the response. I know there are a bunch of them out there. but I'm curious what specific product the OP used to get his car going. This is an interesting topic, and I think it would be nice to have a closure to help others in the future (including myself).

I just bought a parts car, had a running motor 4 weeks ago, as evidenced by the oil change receipt. Car died on the interstate, and sellers mechanic says it's VATS. Could be anything, but car has exact symptoms of this car. It's a parts car, so I'm not gonna spend a fortune getting it running, but it would be nice.

RBob

iTrader: (1)

[QUOTE=two-if-by-sea;6119758I just bought a parts car, had a running motor 4 weeks ago, as evidenced by the oil change receipt. Car died on the interstate, and sellers mechanic says it's VATS.[/QUOTE]

Once the engine is running (over 400 RPM is "running"), the VATs input to the ECM is ignored.

RBob.

two-if-by-sea

iTrader: (22)

Thanks for your response. You are absolutely right. I swapped the in-tank pump and filter, still nothing, though it was spraying fuel. I never checked before, because I didn't think of it, and I wanted to swap the pump anyway. So swapped the plugs, wires, cap, rotor, coil and ICM. Started right up, and ran like a champ.