Ok, so I have done searches for about 2 weeks now and have not found a resolution to my problem, so I am starting a thread to hopefully get some ideas. I have a 1990 RS 3.1L ..engine is bone stock. I ran out of gas not too long ago in my driveway. Since then, the car has been running weird. I hear the fuel pump kick on, and I hear the fuel pump relay click on. I just changed the fuel filter yesterday.
Here's a list of parts I have replace AFTER I ran out of gas:

Spark plugs
Plug wires
Distributor cap and rotor
Ignition Module
Coil
MAP Sensor
IAC Valve (and readjusted per spec)
TPS
O2 Sensor
Air Filter

So, what happens now is...I turn the key to start the car..it STARTS normal, but then it starts to die down and idles extremely rough, the whole engine starts shaking and i spits and sputters, and sometimes stays running, but as soon as i tap the gas, it cuts off. I had someone spray starting fluid in the TB when I turned the engine over, I got the engine to run perfect, but only when my foot was on the gas, as soon as I let off the gas, it stalled. I checked for vacumm leaks with a gauge, but there is none. I took the fuel lines off by the engine, and its getting clean fuel up there. I don't have a pressure gauge to check fuel pressure. The throttle body is clean, as well as the IAC Valve. I am so stumped and can't find a resolution...PLEASE HELP!!

 

have you changed the cat converter?

 

There's nothiing inside my cat. haha..it got clogged a long time ago and I didnt have the money to replace it, so i just hollowed it out. I never had a problem since. But I have back pressure coming from my exhaust. It's def. not an exhaust problem tho.

 

Any other suggestions?

 

i had a friend here at work and he was having a similar problem.

you need to check your fuel pressure
sounds like your pump is going out. it may have picked up some rust when you ran out.

 

Check/change ur oil if you havent. I dont know if it would solve ur problem, but it might help with some of the engine shake..

 

Well, I just performed some tests. I took the air tube off, and sprayed some starting fluid in the TB. Then started the car, it started perfect, but then again slowed down to a rough sluggish idle. When I opened the butterfly valve slowly, the engine started to slow down and almost stall..but when I sprayed starting fluid in the TB with the butterfly valve open, the engine would run perfect. but the second I stop spraying starting fluid, the engine would die down and stall. I pulled the codes and got 22, 33, and 35. I replaced my TPS, and checked the connections to it, seems to have good connections and TPS is working correctly. But, I decided to clean my relay connections with a wire brush. All of the connectors sparked when I cleaned them except for the one on the driver's side on the firewall closest to the fender. From my understanding, code 22 also means fuel cutoff relay is shorted. I have no idea what the fuel cutoff is, where it is, or what it does. But I believe this could have something to do with my problem. Does anyone know what that relay is that I was talking about by the fender? It was the only one that did not spark when I cleaned it, which leads me to believe it's not getting power and causing something to not work. Any suggestions?

 

anybody?

 

any suggestions?

 

please help!

 

Have you checked to make sure you don't have any big vacuum leaks?

 

Yes, I hooked up a gauge, no leaks at all. It's either a fuel delvery problem, or an electronic problem.

 

I went back and reread the original post and you said you check the vacuum already, so my bad. If it run with starting fluid and you don't have vacuum leaks, I'd disconnect the fuel as close to the injectors as possible and see how much flow you have. You probably have something clogging the fuel system somewhere.

 

I know I should check the fuel pressure, but I don't have a pressure gauge. I might get one tonight depending upon my work schedual. But is there a possiblity my injectors are clogged?

 

Quit throwing parts at it trying to guess what it could be and get a fuel pressure gauge. Running it out of gas could have caused the pump to overheat and now it's on it's way out.

 

I don't think using a pressure gauge would be the first way I would troubleshoot this, especially if I had to go out and buy a gauge. Also, I wouldn't do this with the engine hot obviously. Disconnect the fuel line and see how much flow you have.

You can have plenty of pressure and not have much of anything with regards to flow. The reverse however is not true. If you don't have pressure you'll never build up much flow.

 

Well, how would I know if my fuel pump is going bad without checking the pressure?

 

If you crack the fuel line and have someone turn the key on, you'll know instantly if the fuel pump is working or not. Since it seems pretty obvious that fuel starvation is the problem, you'll also know which direction the problem is in.

 

I've done that in my old tests (stated in my orginal post)..its getting clean fuel up to there. I just need to check for pressure. But, I also noticed that If I turn the key without my foot on the gas pedal, then as soon as it starts to turn over, quickly start pumping the gas pedal, for about a half a second, u can see the engine trying to rev up, then it just bogs down and dies. It sounds like it is trying to get fuel, but isn't getting enough. Is that also a fuel pump sign? or injectors? I was also looking into some possible relay problems. My fuel pump relays (both of them, and the fuse) are working fine. I also hear the fuel pump prime when I turn the key. This is killing me!

 

I think you may be missing my point. Pressure and flow are not the same thing. For instance, if you have a garden hose with a valve on the end of it that stops the water flow, you can turn the hose on and have lots of water pressure and absolutely no flow. This is why flow meters work the way they do, they have no effect on system pressure, they just restrict the flow of whatever they are measuring.

If you pressurize the hose and then turn off the spigot, the hose maintains the pressure. If you then crack open the valve, you get flow momentarily until the pressure drops off. If you intalled a pressure gauge at the valve and pressurized the hose you would be able to detect that pressure. If you then closed the spigot, you would continue to see the pressure at the gauge since it is a closed system.

My suspicion is that there is an obstruction in the pump/fuel line/injecters/etc. When you power up the fuel pump, it pressurizes the system. This would account for why the motor attempts to start but doesn't keep running. Once the pressure in the fuel system is bled off by the injectors turning on, the restriction, wherever it is, is inhibiting the flow of fuel.

The only way to know for sure if this is happening is to crack open the line and see how much flow you have and also if that flow is sustainable. If your fuel pump is in the tank, break the system at the ouput from the tank and see what happens. If you have good flow move on to the next point where you can open the system. Eventually you'll be able to locate the section where the obstruction is.

 

Ok, I gotcha, sorry for the misunderstanding. I checked the fuel line when i was putting the fuel filter on. I left on line off (the one from the tank) and turned the key, I did get fuel. Then I connected both lines and then opened the lines up by the injectors, I turned the key on, I have flow. I don't know if this is normal or not, but the flow was only for about 3 seconds, then stopped. The only way to get the pump to get more fuel was to turn the key off then turn it back on. Then it would flow again for 3 seconds and stop. Is this normal?

 

I don't know if that is normal, but if the flow is consistently for on the same amount of time each time you turn the ignition on, it would seem to probably be by design. If the time varied, I would be much more suspect that something is blocking the line somewhere.

If you have access to a graduated cylinder or beaker, you could check the flow rate by turning the pump on and measuring the volume of gas out. The pump should have a published flow rate specification. That would tell you if the volume of gasoline being delivered was correct.

I think at this point, I would be looking into whether or not the fuel pump is supposed to cycle off the way you are describing. If it is not supposed to be doing that, I would check in to the circuit controlling the pump is see if there is something shutting the pump down. Such as a fuel safety shut off.

 

Exactly! That's what I've been trying to figure out this whole time, but nobody seems to be seeing my point. I keep getting code 33. From my understanding, this has to do with the MAP sensor, I replaced the MAP sensor, and all connections are perfect, normal voltage, and vacuum lines are fine. But from what I understand, code 33 ALSO has to do with the fuel cutoff relay being shorted. I noted in an earlier post that I am not getting power to the relay on the firewall closest to the front fender on the driver's side. I was wondering if this could be a factor in my problem. Possibly there's a short or something and is causing the fuel to shut off once the engine is warm. I'm not too sure, does anyone know what that relay is on the firewall? If that isn't the fuel cutoff relay, then where is it?

 

How sure are you that the initial problem was running out of gas? Is it possible that the fuel pump just quit working? It is completely possible that this is an electrical problem.

 

This is the reason why I wasn't so quick to replace the fuel pump, because when the car broke down initially, the computer kept throwing codes for sensors (TPS, IAC Valve, MAP) ..but after replacing the them, nothing changed..I tried the whole starting fluid thing (stated in earlier post) and realized it was a fuel issue. I changed the filter thinking it would help, but it didnt change anything even a little bit. And, no, I'm not sure if running out of fuel was the problem, but what I do know is, after I ran out of fuel is when I started having problems. The car ran and drove, but was hard to start, and kept getting harder to start, same thing its doing now, started perfect, but then idled rough, but before it broke down, the idle would level out back to normal. I've had a bad fuel pump before in this car, but it never threw any codes for sensors, that's why I believe it is an electronic problem that controls the fuel. I've had this car for 4 years, and know alot about how to fix it, but this is by far the weirdest problem I have ever seen with a car, and even 5 other experts cannot come up with a solution after looking at it, all they said was it must have to do with the circuit controlling the fuel delivery.

 

UPDATE: I adjusted the timing a little, and the car idles normal now, and the SES light turned off. BUT, now, at WOT, the engine dies down, and pops in the TB. But when I let off the gas a little, it's fine. I'm gonna change the fuel filter tomorrow and see if that helps..like I said before, there is nothing in my cat. and I even checked to see if there was a clog by disconnecting it, but there is none. Any suggestions as to what this could be?

 

It sounds like your timing is way advanced. Get a light and verify that the timing is in spec.

 

So, I checked the timing..it was at 12. I used the light and moved it to 10 (which is spec) The car idles a little better, but did not solve my problem, and there's a lot more popping in the TB. Could I have a bad TPS? Bad fuel pump? I'm so confused and just want to fix this thing! It's a nightmare!!

 

my 92 firebird had problems trying 2 idle and sometimes it would stall out i changed the fuel heat sensor and its run fine since its like a 20 dollar sensor try it if u want im not sure if that will fix ur car though

 

fuel heat sensor? where is it located? and what does it do? I don't want to just change stuff out just because it sounds like it might solve my problem. I want to be sure of what I am doing, so the next time it breaks down, I know about it.

 

Take it to a mechanic.

 

I would if I can get it to a mechanic..but I know lotss of mechanics, one of which own his own car dealership and body shop..none of them can figure it out.

 

Should I replace the fuel pump?

 

Well there's a long weekend coming up, might as well.

 

please guys, im trying to get some real advice, not just "take it to a mechanic....sure, replace it" I don't have a long weekend coming up, I'm very busy this weekend actually. There has got to be a solution to my problem. Please, I need to get this car moving.

 

After rereading the last several posts, it would appear that after adjusting the timing, the car idles normally now and only shows problems at WOT. I suggest driving the car for awhile and see what happens. I can't remember driving any of my cars at WOT during regular dailly driving.

 

I've already tried giving advice and it was shot down. Think I'm just going to stop giving advice and make stupid comments all the time now.

 

changing the fuel pump didn't work. anything else it could be?

 

I think it would be in your best interest to get a wiring diagram. This will show you where to find the fuel shutoff relay. It seems I remember some GM cars around that time had two relays, the first kicks on while trying to start the car (the three seconds) and the other is in play while the car runs. Also, I think there is a fuel pressure regulator that is internal to the TB? I know my 93 suburban has this. Normally with a bad fpr you can get the darn thing to run though. Back to the relay...........I think the one on the firewall is for the startup, but if you still see 12v plus after it is running it is for both. Is it a gray wire where you get twelve volts? Have you followed all the way back to the tank to make sure it stays tweleve volts and doesn't drop? Also, is your ground good to the tank..........and input of the sender? I'm making an assumption this is an in tank fuel sender?

 

Check your fuel injectors. Sometimes when you run it on empty alot you can damage the fuel injectors really easily. Another member on here found out that three of the injectors stopped working.

 

My relays are getting 12v. They click on also..the fuse is fine. All the wiring on the fuel pump is brand new, just replaced, changed the fuel pump motor and sock. connections and volts are perfect in the fuel pump. I think it might be injectors. Can I check to see if the injectors are working by removing the spark plug wires from the engine? I'm trying to avoid buying a fuel pressure gauge, and also trying to avoid removing the plenum. I figure removing the spark plug wire will eliminate one whole cylinder, so, if the injector works, the engine will run rough once unplugged, if injector is not working, then there will be no change...correct?

 

that could be one way to check. I just took one injector out one at a time to see if they were dirty or damaged. Try your way and see what happens. You never know.

 

But you have also siad the thing idles perfectly when giving it a shot of starting fluid....this does not point to an injector problem? You have also said you don't get fuel pressure beyond the 3 second start up interval. You need pressure past thisa point, not sure though how much on a 90, but I would think you would easily be able to tell that you get SOME pressure. Does anyone know where the fpr is on a 90?

 

[quote=90 Camaro;3759882]UPDATE: I adjusted the timing a little, and the car idles normal now, and the SES light turned off. BUT, now, at WOT, the engine dies down, and pops in the TB. But when I let off the gas a little, it's fine.quote]

I don't know if anything was changed between now and the time this was posted, but it sure doesn't sound like an injector problem. If something was changed, I'd suggest you change it back.

 

Every part on the car came from the factory, or is a direct OEM replacement part. The timing is set at spec. The only thing I changed was the timing. This is def. a fuel delivery problem. And the only thing I haven't checked for fuel is the injectors. I see alot of problems with these stock injectors.