It's kind of a long story, but here are the basics:

1 1/2 months ago installed a vortech supercharger. The car ran great for about 2-3 weeks. I drove it to work on April 25th and no problems at all (this was the last drive before 1 week of vacation). Yesterday morning i started it up and it started right up with no problems. I was standing about 30 feet away from the car talking to my neighbor for about 5 minutes, and while standing there the car just shut off. no noises, smoke or signs of a problem. So i walk back over to the car and try to start it, and it cranks but won't start. After about 5 minutes of looking under the hood and trying to get it re-started(didn't see anything obvious like fluid anywhere, or any wiring disconnected) it finally starts and immediatley dies. This happends a couple of times before it starts and seems OK. So it is idling fine now and i tap the gas pedal a few times to make sure it sounds normal, and everything seems good. I pulled out of my driveway, and within a half miles distance, it dies again. It was a stall and re-start fight to get back home(running very poor when it did run at all). I searced the boards yesterday and thought maybe i needed a new CTS. Bought one on the way home and put it in with no luck, in fact it won't start at all at this point. I checked at the coil & at #1 plug for spark and i have plenty of it. The only other odd thing is the strong smell of gas under the hood after about 10-15 seconds of cranking. I finally got it to start again last night briefly but I had to give like half throttle just to start it, but it ran like crap! Chugging and sputtering and sounded like it was only running on 4 cylinders or something. I checked for codes and came up with #11, #13, #14. BTW, it's a 90 L98 GTA TPI. Anyone who took the time to read this LOOOOOOONNNNNNGGG post, and could offer some advice would be greatly appreciated.

 

I'm not much on the blower end of things, but these are what I'd look at if I had this problem on a regular TPI...

Often a sudden vacuum leak can cause things like this. I'd check vacuum lines to make sure one didn't split or crack on you, check the voltage on the TPS (.5 or so at rest/idle, max of 4.5 or so - check with engine off but key one), check your fuel pressure, and maybe the fuel filter. The smell of gas should be a symptom of flooding or a leak somewhere, so I'd also check the injectors to make sure one of more aren't leaking or have a bad electrical connection. When it's running can you use a mechanics stethoscope to see if they are all clicking?

It's a long shot, but if you still have the charcoal canister you might check it for being full of fuel and replace it's filter if it is.

Good Luck, and be sure to tell us what it ended up being.


- Vern

 

Thanks for the reply! I have a vacuum guage that i installed when i did the blower, and when i do get it to start i have to keep the throttle at least at 1/3 just to keep it running, but the vacuum guage reads right about where it did before the problem started. How do i check the voltage of the TPS? My next thought after last night was to just replace the TPS, O2 sensor, and fuel filter, and if none of those do it, try to get a new ECM. I am just amazed at how fast this problem arose with no symptoms. That is what lead me to believe that it was one of the sensors. Is that a logical way to look at it?

 

Sensors, probably. ECU, doubt that is the problem, I don't think they fail too frequently.

As for testing the TPS, it's actually pretty easy. There are 3 wires going into it. One is the signal to the ECU, which varies in voltage from .4 to 4.8v or so, one is the "reference" line (kind of like a ground), and the other is the power feed. I just stripped a tiny bit of insulation off the reference and ECU signal wires and read the voltages with a voltmeter. Should be around .5-.6v at the idle position, and then ramp up to around 4.5v when you rack the throttle body to WOT. Then just tape the stripped insulation areas back up when done. Some guys manage to get probes into the end of the connector, but I couldn't see how to do that.

Make sure you have the key on, and this has to be done while the TPS is connected to the electrical harness, obviously.

There are 3 wires going into the connector, on my 91 Firebird there is a black one on top, a blue in in the middle, and a white one on the bottom. The 2 lines you need to measure the voltage between are the top and middle ones.

Hope this helps, and Good Luck!

- Vern

 

might want to get your ignition module checked, too.

 

vernw–Thanks again for the info. I will test the TPS before I spend $50!

PhilM– Is there a way to test that myself, or do i need to take it somewhere?

 

unfortunately, you have to take it somewhere. Advance does it for free, and maybe Autozone(?) Personally, I have seen them go bad and do all sorts of weird things, but your problem sounds just like the one I had a few months back in the truck. It's a quick and easy fix if that's the trouble...

 

ok, you checked that you have spark.

you said there was a strong odor of fuel.

and the car did sit for a short while..


im going to take a wild guess and say that the engine is getting flooded with fuel.

on a normal TPI, that would have me looking at the injectors.... but im pretty sure that kit uses a FMU.

first thing id look at is the fuel pressure... i think the FMU might be sticking and thats jacking up your fuel pressure.... causing the car to stumble rich, and eventually flood and stall.

 

btw, please dont go replacing any sensors.

theres a way you can test almost all of them or atleast prove they're bad.

all you do when you wildly replace sensors is introduce the chance of messing somthing else up... and it wastes money too.

 

MrDude_1– OK, I see what you are saying. And yes, it does use an FMU. I think that may be something to seriously look at. I think the FMU is a good suspect, considering I have had the car for 3 years and it has sat at times up to 2-3 months without being started with no problems to speak of, and the fact that the FMU is a new component to the fuel system......hmmmm I think you may have nailed it. Do you know of a way to test and see if it is sticking open or not?

 

i would put a fuel pressure gauge on the car and start from there...
i dont have a FMU, so i dont know exactly how yours works or anything specific.

 

Sounds like a fuel pump or pos mass air flow sensor if you are running one ck fuel pressure.

 

Just an update..

Too many times these threads just die with nobody posting what ended up being the problem, and what fixed it. So here is the rest of my story.

Originally I had a code 13(o2 sensor) & 14(TCS). Well I ended up replacing the TCS and no change. I started checking the fuel pressure issue, and seemed to have OK pressure, but the flow rate was a little low, so I changed the fuel filter. The old one was in pretty bad shape. I could barely blow through it, and it had a rusty color to the fuel that was left in the filter. I thought for sure this would solve the problem, but crossed my fingers and tried to start it up with no luck. So I decided to check the codes again. Well now I am getting code 23(MAT sensor). Jeez, how many sensors can fail at one time? By this time I start really looking at all the codes that a computer can possibly throw and I noticed that every single code included the possibility that the ECM was faulty. With no real way to check the ECM itself I could have spent $300 and/or hours of time testing all of these sensors, so I took a reverse approach to the problem. I will replace the ECM ($72 and 10 minutes of my time for a reman. at advance auto parts) and see if the problem still persists. At least this way I will know that I am truely getting a code and not just false info from the ECM. Last night I put the ECM in, and it fired right up and ran smooth.

 

Glad you found the problem, and appreciate your posting the solution. Have a Great Day!!!


- Vern