So my car suddenly died on me.... It will start and run really rough for 1 second and then die. Heres the story... i installed a chip from tbichips.com and it worked great for 2 days. But then it all of a sudden died while i was driving it. When i would try to start it, it will run really rough for about 1 second and then die. So then i put my stock chip back in and the same thing happened. Im not really sure whats wrong. So today i changed the fuel filter, just because i had no idea when it was changed last. Still does the same thing. Im not sure, but i dont really think it had anything to do with the chip. I have spark, fuel, and air, i dont know what could be the problem, unless something got screwed up with my ecu.
Any ideas?

 

I would start by re-setting your timing. Make sure to first disconnect the electronic spark advance wire. Make sure you dont have one or more fouled plugs, check all the ignition wire connections. Also make sure all of the vacum lines are in place and not cracked. The most common one ive found to pull off is the one that runs to the cruise bowl, or retun canister.

 

The timing should not have changed. Am i right? Also, the plugs were replaced about 3000 miles ago, and all the plug wires are good and i am getting spark. No vacuum lines are off or leaking. Now im thinking maybe its the fuel pump? I dont know. I have no way of checking my fuel pressure

 

If you had a chip burned many things could have changed, including the timing. A fuel pressure gauge is cheap, and is good to have any way. You can very quickly tear apart the tbi unit, and check or replace the fuel pressure regulator once you know you have pressure going to it. These motors are as simple as they come, you cant really do much except replace parts, the sad thing is not knowing what to replace. Nothing is very expensive, so pick a spot to start and start replacing things until you get it. Did you happen to put one of those stupid cheater resistors on that tries to trick the ecu into seeing a cooler temp? Did you double check to make sure the timing wire is connected? I know that sounds stupid, but when you are rushing, it gets easy to overlook and forget.

 

Nope, all i did was install a chip from tbichips.com. But i really doubt that the chip had anything to do with it. There are literally hundereds of people on this fourm that run his chips and never have a problem with them. Im really thinking its my fuel pump now. Now i just need a way of checking my fuel pressure. I would like a gauge, like one that installs in the dash. Does anyone have any suggestions for one that will work with tbi?

 

Fuel pressure guages need fuel, which would mean running a fuel line inside the car - not a good plan.

Crawl under the rear end, hold ear up against gas tank, and have someone turn the key to on (not start) - you should hear the fuel pump whine for 2 seconds while it primes - then you'll know whether it's working.

If it's working, then have someone start the car while you watch the injectors - they should spray a nice cone shape spray pattern, no dripping or anything weird, just nice cone pattern. That'll rule out bad injector(s) - and if they are spraying decently, then you should have decent fuel pressure - but a $15 fuel pressure guage won't be a bad idea either - cut the rubber feed line in the middle and install there with hose clamps. The feed line is the largest of the 3 lines, and the hose should say 3/8 on it (return line is slightly smaller and hose reads 5/16 on it).

 

Ok thanks. Well i ended up renting a fuel pressure test kit from autozone so ill try that out tomorrow.
Can injectors really go bad instantly? Because its like one second the car was running beautifuly, and then the next it wont even start. So that leads me to believe its the fuel pump. Ill have to do some testing first, before i go through all the trouble of replacing it.
Also, i have heard that GM had some sort of system where if the oil pressure drops below a certain point, the fuel pump is automatically shut down. Is this true? I dont know, but thats just what i was told. My oil pressure gauge in the dash hasnt worked since ive had the car so i was thinking maybe my oil pressure sending unit failed and shut down the pump. How would i test any of that?
Also does anyone know any good links to threads about changing fuel pumps? Ive never done it before, so i just want to read up before i try it

 

First - listen for the pump like I said.

If no pump, then try the fuel pump relay - there are two relays in a bracket drivers side firewall between the brake booster and fender - Two 10mm screws hold the bracket to the firewall. Some cars they are the same, some cars one is square and one is rounder looking. Anyway - one is for the fan, one is for the fuel pump - the one for the fan will have a large black wire with a red stripe - the other is the fuel pump relay. Check the connector for signs of shorting (burned). If good, try replacing the relay and see if the pump runs then. The ECM runs the pump through that relay.

Sorry I didn't explain that last night

The Oil Pressure Sending Unit (OPSU) is usually located above the oil filter. BUT - the function is reverse of what you heard. In theory, if the relay isn't functioning properly, the car would still run - when the OPSU gets oil pressure, it runs the pump - but it takes a minute of starting for the oil pressure to build enough to enable the OPSU.

For future reference... the OPSU has a fuse located in a weatherpack on pass side tucked in fender behind the battery. It is powered from a wire directly off the power distribution block (between battery and radiator), to that weatherpack fuse, and straight to the OPSU - oil pressure switches this 12v directly to fuel pump. So, the system operation is 1) turn key on, ECM sends signal to relay, pumps runs for 2 sec to prime the system 2) start car, oil pressure comes in and OPSU runs pump the rest of the time 3) IF no oil pressure (ie you turned the car upside down wrapped around a tree and your trapped in the car with sirens on the way) then the pump stops running as a safety feature so your not getting soaked in gas while things are sparking all around your mangled body like in the movies (dramatic huh?) One more thing for future reference - the OPSU can go bad in such a way that it will run the fuel pump 24/7 regardless of the key (since it's got a direct battery connection). It can "think" it's got oil pressure when it doesn't really. This will drain the battery in 2-3 days.

One more thing - not sure the Autozone test kit is going to help you. It comes with fittings for a schraeder valve which the TBI cars don't have. So, if you don't want to cut into the fuel line to install a guage just yet, start with your ear and your eye and see where that gets you.

 

Yea, when i went there, that was one of the first thing i asked... "Does it come with an adapter for TBI vehicles?" And the dude behind the counter had a blank stare on his face lol. So im like "You know, because they dont have schraeder valves...." And of course he had no idea what i was saying haha. I hate that store, just for that reason. Thats why i usually go to NAPA or Advance. Anyways.... yes it surprisingly did come with the TBI adapter. Thanks for your help, you seem to really know your stuff. Its ironic that your name is camaronewbie Ill be doing some testing today and ill let ya know what i come up with

 

Ok so that was a little confusing but i think i got it. So the car would still run if the OPSU was not working, right?

 

Well - that's a debateable point

I say it won't run if the OPSU is bad. Some theorize that the OPSU only runs the pump if the relay/ECM circuit is bad. But it's my opinion that there's no magical "switching" between circuits here.

My theory is, that the ECM/relay function ONLY works for the priming function. Then the OPSU takes over for the continual running of the car.

The injectors need primed since there's no fuel bowls like in a carb, so there has to be a spray of fuel into the cylinder to fire off initially. There's no way that I can see that the ECM would "know" to do the 2 second prime, and then stop, and then start again after the car has been started - that's just too involved for those very limited old computers.

And, why would the OPSU be wired with it's own fuse, and have a direct uninterupted connection to the battery (always hot) instead of having a hot-in-run connection, if it was only serving as a "backup" way to run the pump.

So, I'm confident that if the OPSU is not functioning properly, that the car will start but not continue to run. But I never tested the theory before I swapped to a carbed motor.

So to answer the question, I say NO - the car will not continue to run without a properly working OPSU. I could be wrong, I've been wrong before (just ask my wife, to her I'm always wrong ).

 

im having the same problem. it sucks.

 

Got her running today!! First i listened to see if the fuel pump primed, like you said. And it seemed to be working properly. Then i checked my fuel pressure and i only had 2 psi haha. Not healthy. But that explains why it would start, but not run. So then i replaced the fuel pump with a new one from NAPA. The problem was not actually the fuel pump, but the little rubber hose that connects the pump to the metal fuel line (in the tank). It got so deteriorated that it developed a small hole in it, so i think thats where i lost most of my pressure, and fuel was just spilling back into the tank. But i ended up replacing the fuel pump too, just because. I tested my fuel pressure again and i was right at 14 psi. Perfect. Then she started up and ran great

 

man thats sweet! i gotta find my fuel pressure gauge and check that. i have the pump to replace but i dont want to install it if thats not whats causing the problem.

 

Yea, im pretty sure my pump was ok, but i just replaced it anyways, since i had to take it out to change the hose. Also, i didnt drop the tank, i just pulled back the carpet and cut a hole. But i took my time and actually did it right. I found a link of a guy who did it and i did pretty much the exact same thing. http://www.turbobuick.com/forums/tur...utes-less.html