96 TA Fuel Pump Issue, Please Help

[Breetai96]

Was getting some food, thought I had enough gas to get where I needed to go and back. Ran out of gas. Put some gas in, car started right up. Then about 4 blocks down, my car just died again. Then got it to my friends place. Checked the fuel pressure in the lines by taking off the fuel filter, and seeing if we can get gas to come through, came through. Did get it to work a few times, but kept going out. Thought it was the fuel pump. Dropped the tank, replaced the pump, worked for the first time. Then Getting same issue again, no fuel. Blew through the lines, and was able to blow no problem. Thinking it may be some electrical or fuel pump relay issue, let me know what you all think?

[Injuneer]

Test the fuel pressure with a gauge on the Schrader valve, not by removing the fuel filter. Hard to follow exactly what you did to test the system. Did you use the +12V fuel pump prime connection up by the PCM? Did you check the operation of the fuel pump relay? Did you verify voltage at the fuel pump connector, right above the rear axle?

[Breetai96]

Well we got it fixed. My buddy who put the pump on, didnt crimp down the hose to the pump, so that had fallen off the pump. Big pain in the butt to rip it all apart again.

[Breetai96]

Well Im getting ready to push my car off a cliff, with all the problems. Thought we had the issue fixed of the car dieing on me. And completly baffled now. Thought the fuel pump was the issue. After we finished replacing the fuel pump, car was running good. No problems. Drive it for a day, didnt die at all. Then last night, leave to go to a friends house, get a block away, and it just died. No sputtering, Just went from full power, working, to dead. Tried to get it started but, got a weak battery, so drained that down. Just cant understand why it will go from working perfectly, to just dead, no sputtering or anything. It is seeming like the fuel pump is getting triggered to just shut off. Any help or suggestions on testing it would be more then welcomed. Gotta be something electrical from what I am thinking. And this all started after I ran out of gas, then filled it up, ran again for 5 minutes, then just dead.

[Jeff_in_Atl]

The first tool anybody should get to work on a computer controlled car should be a scanner.

[Injuneer]

Excellent recommendation - get it scanned. Loss of the low resolution pulse from the Opti will cause the PCM to shut down the fuel system - pump and injectors, for example. And that code does not set the SES light.

Have you confirmed that the ignition switch is not faulty? Have you checked the engine and PCM grounds?

[Breetai96]

Looks like I am gonna have to get a scanner. Had a friend over to give me a jump, and it started right up no problem. Just scared of going far with it, and having it just die on me again. Just not sure what it can be. My opti is real new, and has less then 2000 miles on it. Im starting to think it is the coil sending a response to the computer, telling it to shut down the fuel.

[Breetai96]

well i broke down and got a scanner and am getting these error codes

P0336 Generic Crankshaft Position Sensor
P0335 Crankshaft Position Sensor A Circuit Malfunction

Could that be causing the car to just die after while? Meaning the crankshaft sensor

[BrdWAtti2d]

Take it off and clean it. It's prolly just full of crud. Very easy to get to from under the car. And yea, of course it could make the car run bad.

[Injuneer]

No, the crank position sensor will not make an LT1 run bad. Its only there to monitor misfires. The cam/pseudo-crank position is still measured by the Opti optical sensor, for purposes of ignition and injector timing. Consider the fact that the 93-95 LT1's don't even have a crank position sensor.

[Breetai96]

Well Ive erased the codes on the computer, but saved them on my Scanner. Havent had the car die on me yet again. But havent really driven it far yet either. But I know some of the codes was from when we didnt have everything hooked up, but Im thinking this code may have something to do with my car dieing.

P0122 - Generic TPS/Pedal Position Sensor, A circuit low input

and

P1371 - IC 4X Reference Circuit too few pulses

Havent had the codes come back yet, but then again, havent had the car die on me again yet cause havent driven it really, except for around the block. Let me know what ya think of those codes.

And right now, I can go out, start the car, and it runs no problems, just dont like getting down the road and then it just shuts the engine off and wont start for awhile.

[Injuneer]

Do not use a generic code list, or even the definitions displayed by high end scanners. Use an LT1 specific list. Shoebox has one on his website:

http://shbox.com/1/Dtcs.htm

P0122 = Throttle Position (TP) sensor circuit low voltage

That means at closed throttle the throttle position sensor voltage is less than 0.20V. It has to be above that value for the PCM to set the throttle position percentage. You can view the TPS voltage with your scanner. It needs to be between 0.20-0.90V at closed throttle, should increase smoothly as you rotate the throttle blades from closed to fully open. At WOT it should read about 4V higher than the closed throttel voltage.

P1371 = Distributor Ignition (DI) low resolution circuit

That's loss of low resolution pulse pattern from the Opti. Without that pulse pattern the PCM does not know which injector or which spark plug to fire, so it shuts down the fuel system and the engine won't run. It isn't unusual to see that code "stored".... I think sometimes it sets when the PCM takes a bit of extra time to find the pulse pattern at startup. Clear it and see how soon it comes back. If it comes back and its still intermittent (engine is still running = stored) check the Opti harness connectors for corrosion or bent pins.

[Breetai96]

Well been having more issues with it. I did think that the code P1371 was the ignition coil, so we changed that, and still the same thing. Was able to run it for quite awhile after, and then just dead, waith about 20 or 30 minutes, fires right back up again. We have looked at the opti, and everything is looking good. When it is running, running good. Ive been heaing alot of people tell me it is sounding like the Ignition control module. Just hate to replace that, and still have the issue. Cause thats a 85 dollar sensor. But everytime the car dies, it does put that p1371 code, not before it dies, but only after it dies. Let me know if you think the next step would to be to replace that ignition control module, and really do appreciate all the help and advice.

[Injuneer]

There is no ambiguity about what P1371 means.... it is not set by the coil, it is not set by a failing IC Module. It sets when the PCM sees 720 high res pulses (2 revs of the camshaft) from the Optispark optical sensor, but does not see a single rising edge low resolution pulse. Once this occurs, the PCM shuts down the fuel system - pump and injectors - and the engine will not run.

The only possible source of the code is the Opti, or the wiring harness for the Opti. Sounds like the optical module is overheating.

The IC Module is not a sensor.

[Breetai96]

Well thankyou, finally got it fixed. Was just a issue with the stupid accell optispark I put on there. The thing started going out on me. So got a ac delco off of ebay, with a lifetime warranty, and now working great.