I have a 92 Firebird, 305 tbi. When I start it and let it idle, it will stall after around 5 seconds, but if I start it and put it in reverse out of my parking spot, then drive back into parking spot, it will stay running, but very roughly like it wants to stall. The first thing you notice is a loud sucking/blowing sound from around the injectors/throttle body. When you look at the injectors with the engine running, the drivers side seems to be firing rapidly or sloppily, and not in a cone pattern, while the passengers side doesn't spray at all.

-Both injector connectors gave consistent pulse with noid light.
-All of the fuses under dash, and the one next to the battery are good.
-I replaced the ignition control module (seemed to help a tiny bit).
-I had the fuel pressure regulator done by a mechanic last year (similar situation was happening then)
-None of the steel fuel lines appear to be crimped or leaking.

 

Just went out and fired her up. Kept her running by spraying carb cleaner where the passenger side injector should be spraying, and saw that the drivers side started spraying more of a good cone pattern the more it ran. So, now I'm thinking maybe the passenger side injector is clogged, or just completely kicked the bucket. It's funny how both seemed to stop working for a short period of time, now the drivers side is doing better.

 

I just switched the electrical connectors around from the drivers side injector to passengers side injector, and vice versa, and only the drivers side will spray still. Does that mean the passenger side injector is bad?

 

Both injectors should be spraying in a conical pattern. If only one is spraying then you're starving your engine for fuel. Ohm your injectors. They both should be about 1.3 ohms. If not, replace them. If so, they the one side is plugged. Good luck.

 

I will get a new injector for the passenger side. I read in the old Chilton's manual that you should replace them both at the same time, or at least try to get a new injector that matches the part number on the old injector. Is that true?

 

They are usually flow matched. Two injector swapped is best, but, one should get it running.

 

Ran into this exact situation with a 4.3 TBI. sounds like your injector is bad. It was in my case anyways.

 

Vacuum leak? Most likely, you have a WIDE-OPEN Idle Air Control valve because the idle speed is very low due to the engine running on only four of the eight cylinders.

You have a failed injector. The other injector may be goofy because the manifold vacuum will be very low, and the O2 sensor will be getting false lean information.

Fix the one injector, see how many other problems go away when the engine runs on "all eight".

A "mechanic" that replaces a fuel pressure regulator because one injector doesn't fire is an idiot.






For the record, I was having some issues with my K1500 TBI, so I replaced the TBI with a "Junkyard Fresh" TBI assembly. I had exactly the same symptoms as you--one injector didn't fire, but the wiring was good. Swapping wires didn't make the non-functioning injector squirt fuel.

As it turns out, I got lucky. After running on four cylinders for about five minutes, the sticky injector freed itself, and has been working nicely for several years.

 

Thank you, Antares. I will replace the passenger side injector and see what happens.

 

Yeah, it has to be the injector. I will post what happens after I replace it.

 

Thank you for the information. I will replace the injector and post up what happens afterward.

 

I replaced the injector and let it sit with everything hooked up overnight, because gas spilled out around the engine and I didn't want to start it. Today I finally tried starting it, and it acts like it wants to turn over, then conks out. Kind of reminds me of a dead battery, but the interior lights come on and seem bright, as usual.

 

Faulty battery cable? Corroded connections? Defective battery? A voltmeter would be a handy tool for diagnosing the electrical problem.

This current problem seems unrelated to the prior injector issue.

 

Have someone try to turn it over while you watch the injectors. Any difference than before? Conical spray, dripping, no spray? Replaced your fuel filter lately? Sounds like maybe a fuel pressure or vacuum leak problem. Any check engine light/service engine soon light? Check for codes.

 

I have her back running fine again! Guess what it was?? Yes, it was a bad fuel injector that I replaced, but I didn't do enough to keep fuel from going down into the throttle body, so some of the cylinders got flooded out . After many weeks of researching, getting under the car, and testing, I figured out it was flooded. It was a pain to get all of the fuel out and let the engine dry out. But, after getting the starter tested, new spark plugs, spark plug wires, ignition control module, distributor cap, etc. she's running better than ever.

 

Great! Your persistence paid off. Good to hear it's running. Gives you the confidence to work on other issues as they come up. Good job!