i'll try to make this short, i bought a 1991 camaro RS from a guy for a decent price, saying that it just needed a vats bypass module put in, which he already had ordered through baker electronix (30 hz). i've gone through their site many times as to how to connect it, i know i found the right wire (fuel enable wire, circuit 229) from the ecm. so i cut that wire (dk blue) and connected it to the output wire from the bypass module as it said to do. i also cut the same wire coming out of the bcm (pin E) as it said to do as well.

if i leave the car sitting overnight, go and start it, it'll start up and run for about 10 seconds, then just quickly shut down. from then on if i try to start it, it'll burn a little bit of gas like it's gonna start up and then just die again.

i already have the right resistors in series to bypass the key resistor reader in the ignition, and the starter enables whether the bypass module is in or not...

what doesn't make any sense at all is that once i put the resistors in to bypass the key reader, it ran awesome for like 60 miles, then i went to start it up the next morning, drove about half a mile and it started doing what i explained above, and hasn't stopped.

any hints are helpful i need this car to run. sorry this was so long.

THANK YOU FOR READING

MM3 Gedrose

 

check your resistors a connection on them maybe loose or broken and only connecting at certin times or temps.
this happend to me I just made a new resistor pack up and have had no probs since
also you only need the resistors. you dont need the bypass box also

 

Did you ask why ? Did the VATS quit working, or did the contacts in the key switch stop working ?

That's all you actually needed, if the VATS was working right to begin with.

 

i'm not exactly sure, the guy i bought it from just directly said that it needed a vats bypass module and like i said had already ordered it. i'll check the connections as well though. would my fuel pump just put out enough pressure when i initially start it and then die because the relay wasn't reading enough pressure?

 

That sounds a bit shady (or clueless), but, I don't know the guy either.

The FP relay is oblivious to the fuel pump pressure. It is either on or off. The ECM is unaware of pressure as well.

There is a back up oil pressure switch (above the oil filter) as well. It's meant as a fail safe for the relay.

If the engine will crank and can build more the 4psi oil pressure, the oil pressure switch will make the pump run regardless of the relay working or not.

Regardless of VATS working, the pump should still at least prime with key on.

 

i just made a whole new resistor pack, just in case the other one had a bad connection, and it still doesn't wanna start. right now it's exactly how it was when i ran perfectly for that 60 some miles. when it ran the oil pressure was runnin pretty high, so i don't think that's it. i'm about to go get a multimeter to see if i'm getting power to my fuel injectors when it's cranking. how should the security light work when it's correct? when i have the right resistance in and everything, it'll come on when i first turn the key on for about 3-4 seconds, then turn off.

 

I just found out based on the readings of the security light, and it's not vats related.... what could it be then!? my fuel pump? i can hear it prime every time i turn the key over. what relays could be messed up to stop power to my fuel injectors or not send fuel to my engine?

there is a valve stem type deal next to where the fuel lines come into the throttle body, and if i unseat the stem it squirts fuel out, so it seams like i'm getting sufficient fuel pressure, but i could be wrong! ah i'm screwed lol

 

Classic symptoms of a bad fuel pump. If you've never PUT a fuel pump in one of these cars before....and you attempt this one....you'll soon find out why so many of these cars can be purchased so cheaply when they need a fuel pump replacement. lol. Good luck!

 

Measure the resistance of each of your injectors. After replacing my entire ignition system for what seemed like ignition problems, I've discovered that one bad injector can shut the ECM drivers down making the car not start. This may not be the best advice, but if you give it some starting fluid while cranking you'll see if the ignition is working. If it fires and tries to run, it's a fuel issue. If it still spins and won't fire, it's an ignition problem. I would have been wise to have done this test before splurging on things I didn't really need.

As the other poster already said, you need to verify your fuel pressure. I find that having a gauge permanently mounted on the fuel rail is the only way to fly.

 

yeah i just replaced the fuel filter, thinking maybe it would help, but it didn't. if i take out the left bank fuel injector fuse, but leave the right one in, it tries to start alot stronger than if they were both in. which i'm assuming somewhat means i'm getting enough pressure to feed a few injectors, but not enough... well i'll get to it then, i've heard of people cutting a hole in their trunk somewhere so you could replace the fuel pump without dropping the tank?? is this true? where would i need to put the hole?

 

Before i was about to attempt to replace the fuel pump, i'd figure i'd test the pressure first... connected the gage to the fuel rail and was reading 40+ psig! so i've turned to the injectors, and started taking off the intake plenum, which is kinda a pain. got to be about 100+ degrees outside so i decided to hold off until tomorrow. i'm starting to think that maybe my oil pressure switch went bad maybe?? there is a electrical connection before the wires go underneath the intake plenum to the fuel injectors, i disconnected that and tested it with the key on. i only got power from 2 of the 5 or 6 contact points within the connector... is this normal?

 

TEHE i have done it 3 times. And on the last one i yanked up the carpet and with tinsnips, a sawzaw, and a wee bit of grace i pulled the pump out the trunk. lol But little hint, cut the fuel neck andreplaceit with flexible tube and clams, Helps out ALOT.

 

Fuel pressure is SUPPOSED to be 43 PSI key on engine stopped and 39 PSI running.
Power is delivered to each bank of injectors through its own fuse from the fuse panel under the dash. What you need to do next is to take resistance readings for the injectors per bank. One bank has the green wire for ECM ground control, and the other has the blue one. The other 2 wires in the connector are for the coolant temperature sensor.

Another thing to do is to have your ignition module tested at AutoZone or somewhere that can test it.

Oh, and you have the wrong bypass module. The ECM looks for a 50Hz signal on the enable wire, not a 30Hz signal. You can go to a yard and get a MEMCAL (chip set) from a 1991-93 Grand Prix or something with an FWD 3.1 (up to 1994 in the J-body Cavalier and Sunbird only, engine must NOT be a 3100!) and put that in instead of your factory F-body MEMCAL, like I did, and you won't have to worry about this problem. Your ECM should be showing a code 46...

:edit: BTW, if VATS is working PROPERLY, you don't need the bypass module. Remove it, reattach the ECM DK BLU wire, and see what happens. If the engine turns over, then you probably don't have any problems with VATS.