oxygen454

So to start, the engine is a 5.0L FI in a firebird. The problems started when the car ran out of gas. (Bad idea I know, its my friends car). It won't start without pushing the petal to WOT (full throttle). Also died in a intersection ideling but started right back up.

So I changed the fuel filter and ran it with the fuel guage on it. Everything seemed fine. Started without touching the throttle...
Pressure on prime is 40 to 45 psi
Running pressure was 35psi

So I took the guage off and after a couple of starts, it was back to the hard to start again.

I'm thinking plugged fuel pump filter on the pump itself or the pump is now on its way out. I'm going to cut the old inline filter and check it, also when the car is back, guage it some more.

MAF sensor is clean, cap and rotor is good, and wires are fairly new.

The service engine soon light is on but my obd1&2 code reader says no DTC's present??

OrangeBird

iTrader: (1)

I'm going to suggest crap stuck in one or more of your injectors , and here's why ;

You say this started when it was run out of gas , which likely sucked up all kinds of nasty rust particles and such into your fuel system . Some of these rust bits being stuck holding an injector (s) open would cause you to need to floor the gas to get it to start . Why ? you ask would flooring the gas help with a stuck OPEN injector ? Well , in our fuel injected setup , if you wide open the throttle while starting the engine , it actually shuts OFF the signal to the injectors as a "clear flood mode" and the fact that you need to floor it to start , shutting OFF the injectors , is a sign that your getting too much fuel into it while cranking .

oxygen454

That makes sense. Is there a way to clean the injectors or test them without replacing them all?

I also noticed a lot of air bubbles when I was purging the fuel through my fuel guage to remove the guage. I tried purging when it was running and there was air bubbles still coming out.

Still not sure why the Service Engine Soon light is on but no dtc's present. The scanner said connection was made with the ecm. ( I'm guessing this light is the same as a check engine light, just worded differently)

OrangeBird

iTrader: (1)

That I know of , there really is no easy , on the car way to clean injectors that have been subject to , , That nasty horrible crap that our metal fuel tanks turn into over time . If that turns out to be the actual problem you'd best clean out the entire fuel system starting at the gas cap and finishing up with a set of injectors from a place like southbay . Now , before we go jumping to condemn the injectors , you say you've got a steady on SES light with the engine running ? Well forget the hand held scanner and do a quick search here for the word "paperclip" and you will find out how to have the SES light flash out it's codes for ya , no scanner required

oxygen454

Thanks for the response!
You would think a $500 dollar code scanner would be able to read the codes. Its never let me down. I found the paper clip YouTube video last night as I have used this trick on other Chevy's. I will give it a try. I'm a firm believer of not throwing parts a car to diagnose a problem.

I will try the paper clip and get back to you. Thanks.

oxygen454

I was able to get the blink codes...

12 - Start of code sequence

13 - Oxygen sensor voltage stays between 0.35 and 0.55 volts for 60 seconds. Engine was at normal operating temperature and had been running for at least 2 minutes after start with a throttle angle above 5%.

21 - TPS voltage was above 2.5 volts for 3 seconds when the MAP sensor signal showed manifold vacuum to be 15 pounds or more, or TPS was above 4.8 volts at anytime.

22 - TPS voltage was under 0.2 volts for 2 seconds when the engine was running.

33 - MAF sensor indicated an air flow of 45 gm/sec or more for 1 second when TPS was less than 1/4 throttle and engine speed was under 2000 RPM.

34 - MAF sensor indicated an air flow of 25 gm/sec or less for 1 second when TPS was above 6% and engine speed was above 2300 RPM.

After we were done getting the blink codes, I noticed that the rubber pipping that goes from the MAF sensor to the intake throttle body had a 1\2 opening. I guess the intake pipping had not slid all the way onto the MAF fully allowing some air in.

My friend mentioned that the other morning the idle was fairly high so turned the idle screw back to slow the idle down. When driving home, she had to WOT to keep the car moving. That issue seems to have gone away since I put the MAF pipping on better.

Also the distributor cap is missing a mounting bolt....

So know I need to figure out what the scan code definitions mean and also figure out how to reset the idle screw properly again.

I am also going to check the timing tomorrow.

.

southbay08

To be honest with you the best way to clean and flow test injectors is to put them on a professional flow bench. We can see if they are clogged, check the spray pattern, flow them dynamically, check the resistance and leak test them. If you want to rule out the injectors, you can send them in we can check them for you.

oxygen454

Thanks if it comes down to the injectors I will keep you guys in mind.

So we cleaned the MAF sensor, intake and set the timing which was way off. Then unhooked the battery for 10min to clear the codes and took it for a good drive.

Now the only code showing is 22.
So I guess next step is to check voltages at the tps and if need be... replace the sensor (tps)
Found this good link for checking voltage... Testing TPS

It starts a lot better now. Not 100% yet tho... I cut open the fuel filter and it was spotless. No crud what so ever.