CamaroRS1990Guy

i have a 1990 camaro rs 305 tbi everything is stock. i having trouble the ses light comes on and i read the code and it tells a code 44 lean exhaust. I have put new o2 sensor in and new IAC valve on it even adjusted it put a new vacume line on it made sure it was put on good. what could this be. Oh and also the can will jump when it does this and the tach jumps up and down. when i press the gas pedal down all the way to the floor it just putters then finally picks up. It even hard to start in the cold the engine reves up and down till it gets warmed up. what could that be. Thanks

blue91rs

Fuel starvation problem. When's the last time, or have you ever changed your fuel filter?
Start at your fuel filter, change that, its easy. Also check to see that both injectors are spraying gas into your throttle body. How may miles does your car have? Worst case senario its your fuel pump dying, but I bet its your injectors, one is probably not functioning or is dying.
keep posting with details.

CamaroRS1990Guy

i never have changed the fuel filter but i took it out before and i tried to get all the particles out of it the was alot of black stuff in it. Both injectors are spraying great. there is maybe 165 thousand miles on it. how can i check if it is my fuel pump.

Vader

RS '90,

Blue 91 is on it. Change the fuel filter. Since you've never done it in over 160,000 miles, I think it's due.

You should also check the fuel pressure, and may need a special adapter to test it. If the pressure is between 11-13 PSIG after the filter, the only thing left is the injectors or control system. You said that the injectors are at least spraying. They should be spraying in a regular cone shape, with good atomization and no large droplets dripping from the tips.

The control system could be a problem as wsll. The MAP sensor is crucial to the correct mixture. The TPS voltage should be checked and set asa necessary, and CTS input should be metered or the sensor tested for resistance at a given temperature:

CamaroRS1990Guy

the injectors are spraying in a cone shape with no large droplets but i will change the fuel filter and about the MAP sensor and the fuel pump tell me more about seeing if it is defective.

Vader

RS,

The fuel pressure is critical. The system is calibrated to deliver fuel with the assumption that the pressure at the injectors is within the correct range. The only way to test fuel pressure is with a gauge, and TBI installations usually require a special "T" adapter to temporarily replace the fuel filter and provide an access port for the pressure gauge.

Once you have verified fuel pressure, you should know more. If the pressure is correct, the next step would be to test the MAP sensor. Of course, the hose connecting the sensor to the intake manifold needs to be intact, free from cracks, leaks, splits, or kinks. The electrical connector needs to be clean and tightly seated.

The sensor can be checked with a vacuum source and a digital voltmeter. The sensor should output a 0-5VDC signal at the 'B' terminal. The output voltage is based on absolute pressure at the hose connection. The sensor should output full voltage (5.0VDC) when there is one BAR (barometer, or atmosphere) of pressure applied. This means there is basically no vacuum (0" Hg) and the Absolute Pressure is at 14.7 PSIA. When the Absolute Pressure decreases (due to vacuum) the voltage output on the 'B' terminal should decrease as well. Test the sensor down to about 20" Hg of vacuum, or 0.33 BAR (4.9 PSIA), where the output voltage should be aroud 0.8-1.2 VDC. The voltage should vary in direct proportion to the Absolute Pressure, or amount of vacuum applied. If the MAP output "jumps" or "sticks" at a given point, the sensor bridge circuit or the mechanical diaphragm is failing. Since there is no good way to repair a MAP sensor, replacement would be indicated.

The TPS voltage is also critical to the control system. Make sure the TPS voltage at idle is set at 0.54VDC on adjustable types, or below 1.2 VDC on non-adjustable TPS sensors.

blue91rs

Start with yor fuel filter since you've never done it before. The fact that you said you've removed black "stuff" before is kinda funny, That was probably the original filter..
After you change the filter, post back you're results and you'll get the next step.
I'm guessing its the fuel pump, since you're injectors have a uniform spray. But as Vader said, it could be you're MAP sensor. I'm not sure how much a MAP sensor is on a 91 TBI, (I may need to be corrected here,) but I think thier only like $10 bucks. You may want to just throw one in and see if it helps, At 160k, you might as well.
I would, even if you're problem is solved, check the TPS voltage. Do as search on the boards for "adjusting TPS voltage."
Its real easy, and is very crucial in the proper operation of your engine. It helps your power and your MPG.

blue91rs

oh yeah, the CTS should be dirt cheap also, like $6 bucks. You may want to just replace that also.

The only reason I suggest replacing these parts instead of testing them is the need for a voltmeter to do so. I may be easier for you to just replace the CTS and MAP, if they are as cheap as I think they are.
You will need a Voltmeter or a Scanner to check the TPS voltage though.

Nikotek

I'd agree with everyone else on the fuel filter,but also would change the coolant temp. sensor and the vapor canister element to rule out any kind of vapor lock or vacuum issues(after 165,000 you have to figure your canister or element is full). For a grand total of $15 and an hour of work the differences these cheap items can make is amazing! Cts contributes to alot of different systems,which I found out when mine went bad without any codes. I couldn't start the car,and when it occasionally did-the fuel delivery was so rich from the bad cts that not only wouldn't it idle properly,but it dumped 2 extra quarts of gas in the oilpan when I went to change the oil!

fuel filter,vapor canister element,and cts should make some difference and a cheap way to rule those items out and move on.

Just my .02,good luck
Niko