Firebird wont idle well, or dies like the fuel is being cut off.

Shouldn't be any oil pressure without the engine running. Maybe a problem with the sending unit--gage or wiring circuit. Use an analog gage inplace of sending unit, just to double check oil pressure.

Use a gage and check fuel pressure. Any applicable mil codes? You can check those yourself.

Thanks, you talking about an oil sending unit? I can't find anything like that at the auto store? To check my fuel pressure, I'm pretty sure I have to remove the entire manifold, also to get to the injectors and the valve. Not good. Mainly focused on the crazy oil gauge. When it runs for a bit, It will drop to around 60 before it dies. Im not an experienced mechanic, lol

The oil pressure switch is N7 in the diagram. If mfi should be a schrader valve on the fuel rail, I'll see if I can find a picture.

Do you know how to check for applicable codes?

No sir, I'm learning by doing. There has been no computer hooked up to this car. I would love a pic of where the fuel valve tester is! I do know where the oil pump switches are, is the oil pressure switch different? Is that what sends the signal to my dashboard gauge? Thanks for the help!

my bad, they are called pressure switches, not pump. I know theres 2 of them, one has something to do with cutting the fuel off. Its located right by the oil filter I changed.

As far as the oil pressure switch, it handles both, oil pressure gage and redundant power supply to the pump.

To check for mil codes, you use a jumper wire between the A & B terminals at the datalink connector. Then, turn the key, just till the dash lites come on, no further, no crank. The mil on the dash should start flashing, you count the flashes to get the codes. Your looking for two digit codes. An example, code 12 would be 1 flash a slight pause then two quick flashes. May flash three times before moving to next code, if there are any others?

The data link connector should be lower edge of dash, driver side. The picture is just to show location of A and B.

OK! Much thanks! Assuming a jumper cable is just a plain straight piece of wire, I will try this, and I sure think the fuel oil pressure switch may be my problem. If I don't blow me or the car up, I will get back to ya. Thanks so much!!

Use a piece of automotive wiring at data link connector or a paper clip. A small piece of wire usually works best for me. Not a jumper cable.

Okay, ,, appears to be flashing 12 over and over again. one flash, then 2 quick ones, then pauses and repeats. Going to try to look this up in case I don't hear from you for a while, and Thank You for the tip!!

Code 12 should mean diagnostic mode. If no codes after that, you don't have any codes. You always have the code 12 first.

As far as the oil pressure switch, my database seems to show something different than your post? Databases are not always correct.

Ive got to check the fuel pressure, its running, but not well and not for long if I stop peddling the throttle. If you could find that valve, Ill tear off the manifold if I have to. Ive just been told its on the fuel rails, and they are hidden mostly under the manifold.

The schrader valve shouldn't be hidden, follow the fuel lines. Sorry, I haven't found a picture. If I found one, it would probably just be generic. With tbi, you splice into the fuel supply line, sometimes, I splice in at the fuel filter. Just be sure, no pressure on fuel line before taking any lines loose.

I found this picture. It wouldn't make sense to cover the schrader valve. #4 is the schrader valve, #7 is the fuel block, #3 is the fuel rail.

Yes I found it, its at the very back of the manifold, a chrome looking cap like a bike tire. I'll mess with that soon, I just started it, here's what happens, I unplugged the oil pressure switch, the gauge goes to 80 and stays at all times. When plugged up, its down to zero before I turn the key, then when power goes on, but not starting the car, it goes to 80, then after dying or me shutting it down, but key still to power, the gauge jumps all over, down to 40, back up, back down, just like it wants to play, or is bored? lol Like there's a short or something. Hope this info helps. Ive got to take a break for a while, the heat is killing me. Thanks again for the photo!

sorry when I say jumps around, I meant it moves slowly up and down like its ran by pressure fluctuating. With the motor off but key on after dying.

Use an analog gage just to double check oil pressure.

I changed the oil pressure switch, the gauge is behaving normal now, stays at zero till I start the car, then goes to 60 like it always used to. Didnt have gage to test it. I can also hear the fuel pump prime when turning the key. Im going to try to borrow a fuel pressure tester, there just to expensive Im not working right now. The car always runs a bit better in the morning when its cool. After all this, I guess it will be time to check the injectors. Is there a sensor for heat that may be messed up and killing the car or fuel?

If it is a temp issue, there is the coolant temp sensor? I can't say that is your problem? Glad you got the oil gage working like it should.

Well thanks, but here's the new problem, I'm putting the fuel test on hold for now. When I turn the key to power, the temp gauge is 0, as soon as I start to turn the motor over, the temp gauge goes to 260 and beyond, Ive also heard the radiator fan come on shortly after getting it running until dies. What sends the signal to the temp gauge? Ive surfed around, can't find a solution. Ive checked another car, it does not do this. Sorry to keep bothering you. I really need to get this car running.

Im speaking about the engine temperature gauge

Okay Ive read where a full sweep of the gauge at start up means its working. Just started it this morning while it was cool.Temp showed around 80-100, It ran great at 4000rpm except for a few rpm dips every 4-5 seconds. as soon as I let off the gas, It was all over, didn't even want to start. Well back to checking fuel pressure and injectors, lol

You have a coolant temp sensor that can effect your fan. If the ac is on, the fan will run. If the coolant temp sensor is left unplugged, the fan will run constantly.

You also have a temp sending unit, separate from the other sensor, controls the gage. My info says the sending unit is located at left cylinder head, below valve cover.

Okay thanks. Still haven't found a fuel pressure tester, or tore apart the top to check the injectors, but today I re-did the bypass datalink test. The radiator fan came on automatically, and stayed on the whole time. the error codes were 12 three time, then 15 three times, and just kept repeating the same thing. Where can I find out what each code means, and what does 15 mean? Thanks

The code 15 is coolant temp sensor voltage, too high. I thought 2carpros had a link for obd1 codes, didn't see it?

If you type gm obd1 codes in your search box, should give you all the info you need.

I can give you more info on the code if needed, from our database.

Well alright, unhooked negative battery cable overnight, error 15 went away. I went and rented a fuel pressure tester, hooked it up without turning a key, showed around 10. Then sprayed plenty of starting fluid into the intake to keep it running for a while. When I started it, the pressure gauge went straight to zero! lol but the car was running great off the starter fluid, no missing out or fluttering. The gauge would sometimes go back to 10, but then straight back to zero. I hear it should be around 45. Even though sometimes I can hear the fuel pump prime, is this my problem? If so, can the whole fuel pump be replaced from a hole in the top of the trunk. Im in a dirt gravel driveway. Ive heard about how hard it is to go from underneath. Not an option for me sadly. Thanks again! Cant really afford to have it towed and pay a repair service.

Oh yea the pressure bleeder hose didn't even bleed a drop of gas, lol

Yeah, you can erase codes, that way. If there is a problem on that system, the code will just come back. Maybe it was an old code?

If there is an excess panel in the trunk, you can get at the pump, that way. If I have to lay on the ground or whatever, I use a big piece of cardboard or an old throw rug. There are safety issues with raising and supporting,working under, a vehicle. Safety is your responsibility.

I checked the datalink again after starting the car with starter fluid and pressure reading zero, the code did not show up again. I read where one guy said he couldnt pull the pump out of the top after cutting a hole above the tank, he said it was connected at the bottom of the tank to the fuel line, or something like that, Ive been told thats bullcrap. Do you think my fuel pump is the problem, not the coolant sensor, if so, thats my next project.

also I was told to watch out for spewing gas when I screwed the pressure valve on the schrader unit, there was absolutely nothing putting it on or taking it off. Not even a pressure sound. If the pumps my problem, I'll get on it and get out of your hair for a while. Thanks Bud!

If you have good voltage and ground at the connector for fuel pump motor and no pump action, I suspect the pump. I've seen pumps that would run but not make much if any pressure.

There is a fuel pump test connector, under the hood, firewall, usually battery side of engine. Red wire electrical connector, nothing plugged into it. If you use a jumper wire from battery + to connector, the pump should run, don't have to use the key. Probably should use an inline fuse with the jumper, just in case. I didn't think about that earlier. You still have to check voltage and ground at the rear.

I haven't heard of GM fuel pumps being attached at the bottom, somehow. I have heard of that on other makes, can't remember which make? I think it was a ford?

I will try that, I was just out there messing with it, changed the fuel pump fuse, "even though the other one looked fine" I hear the pump at every key turn, but it doesn't last very long. The fuel pressure starts at 1, then builds up 1-2 pounds with every key turn to power. I do this till it maxes out at 15, won't go any higher, then the car starts beautifully every time but the pressure starts to immediately drop down to zero, then sputters and dies. Going crazy here!! haha checked the datalink again afterwards, still only 12. Maybe I need to find a pressure hose diagram, I don't know,,,,,, Ill try the jumper, 2 wires or one, negative or positive?

tried it with a fuse in the line, now pump doesn't work at all, hope I didn't short out the fuel pump relay. dis-connecting the negetive cable again all night. As soon as pump comes on again, Im going to start to change it. Thanks for the help!!

That's what the test connector is for, won't hurt anything. If your going to drop the tank, you will need to drain it.

Sorry It's been a while, Ive checked around about 91 firebird 3.1 fuel pressure and some say there's that are fuel injected are around 10-15 psi, which is what I have. I have not removed the fuel tank yet, I have removed the Plenum (if that's the correct term) so I could get to my fuel Injectors. The ohms readings (if done properly lol) all on the passenger side are 12. The front 2 on the drivers side are 8-sometimes 7 on
one of them on a different setting on the meter that had a decimal point, the last one is 12. Are the 2- 8's my problem, are the failing or clogged, can I clean them cheaply myself without that $100 kit? And Ive heard about a tool that goes in between the plug and plug wire to check for a spark or power? Whats that tool called? I'm going to check on that some more. Hope your still interested, anything look awry or fixable here before I destroy the rear end or kill myself trying!haha
signed
broke-non mechanic!

Oh yea, I also found that gold metal flexible pipe that goes into the passenger side up front on the plenum completely clogged up. the base where it goes into the electrical boxes was fine. I cleaned the plenum hole out, don't have a clue what it does. More curios about the previous post. Just thought I'd add this info if it helps. Thanks!!

sorry to keep forgetting things, but the fuel pump always primes, and fuel spews out of the schrader unit. Starts okay but still cuts off, but will run fine with gas being sprayed into the intake.

That fuel pressure reading is not correct for MFI. It is correct for TBI. Those lower injector readings, don't sound right to me.

Okay,, It's been a while because of my physical and financial condition mainly,, but to anyone who reads my problems, I finally got the gas tank out, [91 firebird] and didn't have to undo the brake lines, just undo the screws holding the lines by the left tire. I replaced the whole sending unit, float and fuel pump. Had a bit of trouble hooking the hoses back up, new parts aren't perfect for old cars, but they were close enough. And after 1,000 cuss words, and getting it all back together, she started and purred like she's supposed to!!! No more dying after 5 seconds! But be prepared to replace the old sway bar links, and you may need a jack to get them in. But problem solved, I cleaned my spark plugs, and the next thing I knew my fuel pump went bad. Hope this helps any else going through this problem, and thank you 2 car pro's forever! I got my parts at rock bottom auto for great prices!!!! Thanks Guys!!!!!!!!!!!!

You do have to unhook the rear axle though,, be carefull,, Thanks!

Good job.